OT: Ethernet Trivia
Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same sized frame over the same type of media and over the same distance and neither experience a collision. Which will get to the destination first? **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
neither or both whichever way you want to look at it. ""Frank"" <[EMAIL PROTECTED]> wrote in message 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
They would bith reach the destination at the same time (speed of electricity through copper). The difference is in the rate at which the bits are placed on the wire, the Fast Ethernet would be placing 20 bits of information (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT would place on the wire. At least his is my understanding of 100bT vs 10bT.. Anybody else have different(better?) interpretations? -- Kevin L. Kultgen ""Frank"" <[EMAIL PROTECTED]> wrote in message 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia
They should both arrive at the same time. The difference in 10Mbps and 100Mbps is the time between packet transmission (referred to as the "interframe gap). Irwin -Original Message- From: Frank [mailto:[EMAIL PROTECTED]] Sent: Wednesday, October 04, 2000 12:09 PM To: [EMAIL PROTECTED] Subject: OT: Ethernet Trivia Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same sized frame over the same type of media and over the same distance and neither experience a collision. Which will get to the destination first? **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
I believe both would arrive at the same time, i.e. start of frame. However; because of encoding, the packet on 100Mb line would complete the process of sending the entire packet first. Ed **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
I believe this is correct. The first packets will arrive at the same time, but subsequent packets on the Fast Ethernet will arrive more quickly because of the encoding. ""Kevin L. Kultgen"" <[EMAIL PROTECTED]> wrote in message 8rfmco$pgo$[EMAIL PROTECTED]">news:8rfmco$pgo$[EMAIL PROTECTED]... > They would bith reach the destination at the same time (speed of electricity > through copper). The difference is in the rate at which the bits are placed > on the wire, the Fast Ethernet would be placing 20 bits of information > (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT > would place on the wire. At least his is my understanding of 100bT vs > 10bT.. > > Anybody else have different(better?) interpretations? > > -- > Kevin L. Kultgen > > > ""Frank"" <[EMAIL PROTECTED]> wrote in message > 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > > sized > > frame over the same type of media and over the same distance and neither > > experience > > a collision. Which will get to the destination first? > > > > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > > http://www.groupstudy.com/list/Associates.html > > _ > > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > > FAQ, list archives, and subscription info: http://www.groupstudy.com > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia
Easy one. What is you definition of get there? Is it when the first bit hits the destination interface? Or is it when the entire packet is recieved at the destination. Is the wire distance between the source and destination the same? Can we ignore any differences between the host machines, (ie a 486 running NT 4 server vs a dual Pentium III machine running Linux)? Can we assume both packets leave at the same time? Can we assume there are no variable such as switches/hubs/etc between the hosts? Assuming the distance is the same, ignoring host differences, and 1 bit arriving is defined as getting there, and no hub/switches/etc variable, then they will arrive at the same time. Assuming all of the above except that getting there means the entire packet arrives, then the 100mb would arrive first. The serialization delay is 1/10th of what is it on a 10mb pipe. Scott Meyer CCNA, CCDA, MCSE, etc [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Art Pereira Sent: Wednesday, October 04, 2000 12:19 PM To: [EMAIL PROTECTED] Subject: Re: Ethernet Trivia neither or both whichever way you want to look at it. ""Frank"" <[EMAIL PROTECTED]> wrote in message 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
So if this were the case, and they both started at the same time and used the same size frame/packet I would think that the 100Mbps interface would get the packet onto the wire faster hence it would arrive sooner than the 10Mbps interface which would probably still be putting the data on the wire. Correct? Tim - Original Message - From: "Kevin L. Kultgen" <[EMAIL PROTECTED]> Newsgroups: groupstudy.cisco To: <[EMAIL PROTECTED]> Sent: Wednesday, October 04, 2000 12:35 PM Subject: Re: Ethernet Trivia They would bith reach the destination at the same time (speed of electricity through copper). The difference is in the rate at which the bits are placed on the wire, the Fast Ethernet would be placing 20 bits of information (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT would place on the wire. At least his is my understanding of 100bT vs 10bT.. Anybody else have different(better?) interpretations? -- Kevin L. Kultgen ""Frank"" <[EMAIL PROTECTED]> wrote in message 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
They would both start at the same time. The 100bT interface would be placing bits on the wire faster than the 10bT interface and would complete placing bits on the wire in 1/10 the time. But those bits can't actually move any faster through the copper medium. The copper isn't more conductive (it's still Cat 5(e)) and the speed of light hasn't increased. So the bits that are placed on the wire will move through the wire at exactly the same rate. If the bits for 10bT consume 5 meters of cable megth before the NIC moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) before the next bit is placed on the wire. This is just an example, I'm not sure of the exact lengths of the bits on the wire, but the point is that the bits can't move any faster because the speed of electricity through copper is fixed. The difference is that the 100bT card is placing bits on the wire 10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits on the wire 100x faster than the 10bT card (or each bit would be .05 meters (5 centimeters), given the above example). So, on 100bT the end of the packet (the whole packet) would arrive before the 10bT would be done (in fact depending on the size of the packet 10bT might still be sending the preamble or headers), but the start of the packets (first bit of the preamble) would arrive at the same time. HTH, Thanx Kevin L. Kultgen Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one point how long a bit is on the wire but I forgot it. If I have anything that needs clarification (or correction) then please feel free to add it or request it. This is helping me too, because I'm looking at taking the CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). - Original Message - From: "Tim O'Brien" <[EMAIL PROTECTED]> To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Thursday, October 05, 2000 5:49 AM Subject: Re: Ethernet Trivia > So if this were the case, and they both started at the same time and used > the same size frame/packet I would think that the 100Mbps interface would > get the packet onto the wire faster hence it would arrive sooner than the > 10Mbps interface which would probably still be putting the data on the wire. > Correct? > > Tim > > - Original Message - > From: "Kevin L. Kultgen" <[EMAIL PROTECTED]> > Newsgroups: groupstudy.cisco > To: <[EMAIL PROTECTED]> > Sent: Wednesday, October 04, 2000 12:35 PM > Subject: Re: Ethernet Trivia > > > They would bith reach the destination at the same time (speed of electricity > through copper). The difference is in the rate at which the bits are placed > on the wire, the Fast Ethernet would be placing 20 bits of information > (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT > would place on the wire. At least his is my understanding of 100bT vs > 10bT.. > > Anybody else have different(better?) interpretations? > > -- > Kevin L. Kultgen > > > ""Frank"" <[EMAIL PROTECTED]> wrote in message > 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > > sized > > frame over the same type of media and over the same distance and neither > > experience > > a collision. Which will get to the destination first? > > > > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > > http://www.groupstudy.com/list/Associates.html > > _ > > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > > FAQ, list archives, and subscription info: http://www.groupstudy.com > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia
Ahh Kevin, your post reminds me of some research I did when I was putting together my paper on LAN Switching for CertificationZone. I was looking at how to calculate the round-trip propagation delay for 10BaseT networks. Here's a few technical numbers for you you (and possibly other Groupstudy members) might find interesting. --- Beginning of Calculations --- Electrical signals travel in a copper wire travel (propagate) at approximately two-thirds the speed of light. Remembering that the speed of 10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of wire that one bit occupies, by using the following calculation: Speed of Light in a Vacuum = 300,000,000 meters/second Speed of Electricity in a Copper Cable = 200,000,000 meters/second 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit The minimum size Ethernet frame consisting of 64 bytes (512 bits) occupies 10,240 meters of cable. --- End --- -- Leigh Anne > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > Kevin L. Kultgen > Sent: Thursday, October 05, 2000 10:12 AM > To: Tim O'Brien; [EMAIL PROTECTED] > Subject: Re: Ethernet Trivia > > > They would both start at the same time. The 100bT interface would be > placing bits on the wire faster than the 10bT interface and would complete > placing bits on the wire in 1/10 the time. But those bits can't actually > move any faster through the copper medium. The copper isn't more > conductive > (it's still Cat 5(e)) and the speed of light hasn't increased. > So the bits > that are placed on the wire will move through the wire at exactly the same > rate. If the bits for 10bT consume 5 meters of cable megth before the NIC > moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > before the next bit is placed on the wire. This is just an > example, I'm not > sure of the exact lengths of the bits on the wire, but the point > is that the > bits can't move any faster because the speed of electricity through copper > is fixed. The difference is that the 100bT card is placing bits > on the wire > 10x faster than the 10bT card. And 1000bT (gigabit ethernet) > places bits on > the wire 100x faster than the 10bT card (or each bit would be .05 > meters (5 > centimeters), given the above example). > > So, on 100bT the end of the packet (the whole packet) would arrive before > the 10bT would be done (in fact depending on the size of the packet 10bT > might still be sending the preamble or headers), but the start of the > packets (first bit of the preamble) would arrive at the same time. > > HTH, > > Thanx > > Kevin L. Kultgen > > Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one > point how long a bit is on the wire but I forgot it. If I have anything > that needs clarification (or correction) then please feel free to > add it or > request it. This is helping me too, because I'm looking at taking the > CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
Kevin, Great analysis. Does this help at all? Speed of light in twisted-pair cable is 177,000 km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or 17.7 meters, in 10 Mbps Ethernet. 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps Ethernet. (I'm sure you figured that one out already.) It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to make any difference! Priscilla At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: >They would both start at the same time. The 100bT interface would be >placing bits on the wire faster than the 10bT interface and would complete >placing bits on the wire in 1/10 the time. But those bits can't actually >move any faster through the copper medium. The copper isn't more conductive >(it's still Cat 5(e)) and the speed of light hasn't increased. So the bits >that are placed on the wire will move through the wire at exactly the same >rate. If the bits for 10bT consume 5 meters of cable megth before the NIC >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) >before the next bit is placed on the wire. This is just an example, I'm not >sure of the exact lengths of the bits on the wire, but the point is that the >bits can't move any faster because the speed of electricity through copper >is fixed. The difference is that the 100bT card is placing bits on the wire >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits on >the wire 100x faster than the 10bT card (or each bit would be .05 meters (5 >centimeters), given the above example). > >So, on 100bT the end of the packet (the whole packet) would arrive before >the 10bT would be done (in fact depending on the size of the packet 10bT >might still be sending the preamble or headers), but the start of the >packets (first bit of the preamble) would arrive at the same time. > >HTH, > >Thanx > >Kevin L. Kultgen > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one >point how long a bit is on the wire but I forgot it. If I have anything >that needs clarification (or correction) then please feel free to add it or >request it. This is helping me too, because I'm looking at taking the >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > >- Original Message - >From: "Tim O'Brien" <[EMAIL PROTECTED]> >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; ><[EMAIL PROTECTED]> >Sent: Thursday, October 05, 2000 5:49 AM >Subject: Re: Ethernet Trivia > > > > So if this were the case, and they both started at the same time and used > > the same size frame/packet I would think that the 100Mbps interface would > > get the packet onto the wire faster hence it would arrive sooner than the > > 10Mbps interface which would probably still be putting the data on the >wire. > > Correct? > > > > Tim > > > > - Original Message - > > From: "Kevin L. Kultgen" <[EMAIL PROTECTED]> > > Newsgroups: groupstudy.cisco > > To: <[EMAIL PROTECTED]> > > Sent: Wednesday, October 04, 2000 12:35 PM > > Subject: Re: Ethernet Trivia > > > > > > They would bith reach the destination at the same time (speed of >electricity > > through copper). The difference is in the rate at which the bits are >placed > > on the wire, the Fast Ethernet would be placing 20 bits of information > > (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT > > would place on the wire. At least his is my understanding of 100bT vs > > 10bT.. > > > > Anybody else have different(better?) interpretations? > > > > -- > > Kevin L. Kultgen > > > > > > ""Frank"" <[EMAIL PROTECTED]> wrote in message > > 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > > > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the >same > > > sized > > > frame over the same type of media and over the same distance and neither > > > experience > > > a collision. Which will get to the destination first? > > > > > > > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > > > http://www.groupstudy.com/list/Associates.html > > > _ > > > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > > > FAQ, list archives, and subscription info: http://www.groupstudy.com > > > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > &g
Re: Ethernet Trivia
I'm not sure I stated my view properly. The first bits would get there at the same time but the last bits of 100bT would arrive wayyy before the last bits of the 10bT frame. The 100bT could send (almost) 10 frames in the same amount of time that the 10bT sent its one. I know Priscilla already has her CNX so she should be treated as a higher (final?) authority. Kevin L. Kultgen - Original Message - From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; "Tim O'Brien" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, October 06, 2000 6:01 PM Subject: Re: Ethernet Trivia > Kevin, > > Great analysis. > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or > 17.7 meters, in 10 Mbps Ethernet. > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > Ethernet. (I'm sure you figured that one out already.) > > It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to > make any difference! > > Priscilla > > At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: > >They would both start at the same time. The 100bT interface would be > >placing bits on the wire faster than the 10bT interface and would complete > >placing bits on the wire in 1/10 the time. But those bits can't actually > >move any faster through the copper medium. The copper isn't more conductive > >(it's still Cat 5(e)) and the speed of light hasn't increased. So the bits > >that are placed on the wire will move through the wire at exactly the same > >rate. If the bits for 10bT consume 5 meters of cable megth before the NIC > >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > >before the next bit is placed on the wire. This is just an example, I'm not > >sure of the exact lengths of the bits on the wire, but the point is that the > >bits can't move any faster because the speed of electricity through copper > >is fixed. The difference is that the 100bT card is placing bits on the wire > >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits on > >the wire 100x faster than the 10bT card (or each bit would be .05 meters (5 > >centimeters), given the above example). > > > >So, on 100bT the end of the packet (the whole packet) would arrive before > >the 10bT would be done (in fact depending on the size of the packet 10bT > >might still be sending the preamble or headers), but the start of the > >packets (first bit of the preamble) would arrive at the same time. > > > >HTH, > > > >Thanx > > > >Kevin L. Kultgen > > > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one > >point how long a bit is on the wire but I forgot it. If I have anything > >that needs clarification (or correction) then please feel free to add it or > >request it. This is helping me too, because I'm looking at taking the > >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > > > >- Original Message - > >From: "Tim O'Brien" <[EMAIL PROTECTED]> > >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > ><[EMAIL PROTECTED]> > >Sent: Thursday, October 05, 2000 5:49 AM > >Subject: Re: Ethernet Trivia > > > > > > > So if this were the case, and they both started at the same time and used > > > the same size frame/packet I would think that the 100Mbps interface would > > > get the packet onto the wire faster hence it would arrive sooner than the > > > 10Mbps interface which would probably still be putting the data on the > >wire. > > > Correct? > > > > > > Tim > > > > > > - Original Message - > > > From: "Kevin L. Kultgen" <[EMAIL PROTECTED]> > > > Newsgroups: groupstudy.cisco > > > To: <[EMAIL PROTECTED]> > > > Sent: Wednesday, October 04, 2000 12:35 PM > > > Subject: Re: Ethernet Trivia > > > > > > > > > They would bith reach the destination at the same time (speed of > >electricity > > > through copper). The difference is in the rate at which the bits are > >placed > > > on the wire, the Fast Ethernet would be placing 20 bits of information > > > (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT > > > would place on the wire. At least his is my understanding
Re: Ethernet Trivia
I've noticed it taking about 24 hours to get the post to appear on the newsgroup side of groupstudy (Which is the side I tend to use). Kevin L. Kultgen - Original Message - From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; "Tim O'Brien" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, October 06, 2000 6:18 PM Subject: Re: Ethernet Trivia > My brain hurts! &;-) My point was simply that on a short cable, the issue > of how much "space" a bit takes on the cable is irrelevant, n'est-ce pas?? > > We all agree that serialization is the real issue. A 100Base-T port can > output bits 10 times as fast. > > By the way, I never saw my message posted. Did you? I haven't seen hardly > any of my messages posted lately. It's frustrating. > > Priscilla > > At 06:08 PM 10/6/00, Kevin L. Kultgen wrote: > >I'm not sure I stated my view properly. The first bits would get there at > >the same time but the last bits of 100bT would arrive wayyy before the last > >bits of the 10bT frame. The 100bT could send (almost) 10 frames in the same > >amount of time that the 10bT sent its one. > > > >I know Priscilla already has her CNX so she should be treated as a higher > >(final?) authority. > > > >Kevin L. Kultgen > > > >- Original Message - > >From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> > >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; "Tim O'Brien" > ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > >Sent: Friday, October 06, 2000 6:01 PM > >Subject: Re: Ethernet Trivia > > > > > > > Kevin, > > > > > > Great analysis. > > > > > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > > > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, > >or > > > 17.7 meters, in 10 Mbps Ethernet. > > > > > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > > > Ethernet. (I'm sure you figured that one out already.) > > > > > > It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to > > > make any difference! > > > > > > Priscilla > > > > > > At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: > > > >They would both start at the same time. The 100bT interface would be > > > >placing bits on the wire faster than the 10bT interface and would > >complete > > > >placing bits on the wire in 1/10 the time. But those bits can't actually > > > >move any faster through the copper medium. The copper isn't more > >conductive > > > >(it's still Cat 5(e)) and the speed of light hasn't increased. So the > >bits > > > >that are placed on the wire will move through the wire at exactly the > >same > > > >rate. If the bits for 10bT consume 5 meters of cable megth before the > >NIC > > > >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > > > >before the next bit is placed on the wire. This is just an example, I'm > >not > > > >sure of the exact lengths of the bits on the wire, but the point is that > >the > > > >bits can't move any faster because the speed of electricity through > >copper > > > >is fixed. The difference is that the 100bT card is placing bits on the > >wire > > > >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits > >on > > > >the wire 100x faster than the 10bT card (or each bit would be .05 meters > >(5 > > > >centimeters), given the above example). > > > > > > > >So, on 100bT the end of the packet (the whole packet) would arrive before > > > >the 10bT would be done (in fact depending on the size of the packet 10bT > > > >might still be sending the preamble or headers), but the start of the > > > >packets (first bit of the preamble) would arrive at the same time. > > > > > > > >HTH, > > > > > > > >Thanx > > > > > > > >Kevin L. Kultgen > > > > > > > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at > >one > > > >point how long a bit is on the wire but I forgot it. If I have anything > > > >that needs clarification (or correction) then please feel free to add it > >or > > > >request it. Th
Re: Ethernet Trivia
My brain hurts! &;-) My point was simply that on a short cable, the issue of how much "space" a bit takes on the cable is irrelevant, n'est-ce pas?? We all agree that serialization is the real issue. A 100Base-T port can output bits 10 times as fast. By the way, I never saw my message posted. Did you? I haven't seen hardly any of my messages posted lately. It's frustrating. Priscilla At 06:08 PM 10/6/00, Kevin L. Kultgen wrote: >I'm not sure I stated my view properly. The first bits would get there at >the same time but the last bits of 100bT would arrive wayyy before the last >bits of the 10bT frame. The 100bT could send (almost) 10 frames in the same >amount of time that the 10bT sent its one. > >I know Priscilla already has her CNX so she should be treated as a higher >(final?) authority. > >Kevin L. Kultgen > >- Original Message - >From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; "Tim O'Brien" ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> >Sent: Friday, October 06, 2000 6:01 PM >Subject: Re: Ethernet Trivia > > > > Kevin, > > > > Great analysis. > > > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, >or > > 17.7 meters, in 10 Mbps Ethernet. > > > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > > Ethernet. (I'm sure you figured that one out already.) > > > > It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to > > make any difference! > > > > Priscilla > > > > At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: > > >They would both start at the same time. The 100bT interface would be > > >placing bits on the wire faster than the 10bT interface and would >complete > > >placing bits on the wire in 1/10 the time. But those bits can't actually > > >move any faster through the copper medium. The copper isn't more >conductive > > >(it's still Cat 5(e)) and the speed of light hasn't increased. So the >bits > > >that are placed on the wire will move through the wire at exactly the >same > > >rate. If the bits for 10bT consume 5 meters of cable megth before the >NIC > > >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > > >before the next bit is placed on the wire. This is just an example, I'm >not > > >sure of the exact lengths of the bits on the wire, but the point is that >the > > >bits can't move any faster because the speed of electricity through >copper > > >is fixed. The difference is that the 100bT card is placing bits on the >wire > > >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits >on > > >the wire 100x faster than the 10bT card (or each bit would be .05 meters >(5 > > >centimeters), given the above example). > > > > > >So, on 100bT the end of the packet (the whole packet) would arrive before > > >the 10bT would be done (in fact depending on the size of the packet 10bT > > >might still be sending the preamble or headers), but the start of the > > >packets (first bit of the preamble) would arrive at the same time. > > > > > >HTH, > > > > > >Thanx > > > > > >Kevin L. Kultgen > > > > > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at >one > > >point how long a bit is on the wire but I forgot it. If I have anything > > >that needs clarification (or correction) then please feel free to add it >or > > >request it. This is helping me too, because I'm looking at taking the > > >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > > > > > >- Original Message - > > >From: "Tim O'Brien" <[EMAIL PROTECTED]> > > >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > > ><[EMAIL PROTECTED]> > > >Sent: Thursday, October 05, 2000 5:49 AM > > >Subject: Re: Ethernet Trivia > > > > > > > > > > So if this were the case, and they both started at the same time and >used > > > > the same size frame/packet I would think that the 100Mbps interface >would > > > > get the packet onto the wire faster hence it would arrive sooner than >the > > > > 10Mbps interface which would probably still be putting the dat
Re: Ethernet Trivia
That math does not sound quite right. - Original Message - From: Priscilla Oppenheimer <[EMAIL PROTECTED]> To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, October 06, 2000 5:01 PM Subject: Re: Ethernet Trivia > Kevin, > > Great analysis. > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or > 17.7 meters, in 10 Mbps Ethernet. > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > Ethernet. (I'm sure you figured that one out already.) > > It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to > make any difference! > > Priscilla > > At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: > >They would both start at the same time. The 100bT interface would be > >placing bits on the wire faster than the 10bT interface and would complete > >placing bits on the wire in 1/10 the time. But those bits can't actually > >move any faster through the copper medium. The copper isn't more conductive > >(it's still Cat 5(e)) and the speed of light hasn't increased. So the bits > >that are placed on the wire will move through the wire at exactly the same > >rate. If the bits for 10bT consume 5 meters of cable megth before the NIC > >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > >before the next bit is placed on the wire. This is just an example, I'm not > >sure of the exact lengths of the bits on the wire, but the point is that the > >bits can't move any faster because the speed of electricity through copper > >is fixed. The difference is that the 100bT card is placing bits on the wire > >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits on > >the wire 100x faster than the 10bT card (or each bit would be .05 meters (5 > >centimeters), given the above example). > > > >So, on 100bT the end of the packet (the whole packet) would arrive before > >the 10bT would be done (in fact depending on the size of the packet 10bT > >might still be sending the preamble or headers), but the start of the > >packets (first bit of the preamble) would arrive at the same time. > > > >HTH, > > > >Thanx > > > >Kevin L. Kultgen > > > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one > >point how long a bit is on the wire but I forgot it. If I have anything > >that needs clarification (or correction) then please feel free to add it or > >request it. This is helping me too, because I'm looking at taking the > >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > > > >- Original Message - > >From: "Tim O'Brien" <[EMAIL PROTECTED]> > >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>; > ><[EMAIL PROTECTED]> > >Sent: Thursday, October 05, 2000 5:49 AM > >Subject: Re: Ethernet Trivia > > > > > > > So if this were the case, and they both started at the same time and used > > > the same size frame/packet I would think that the 100Mbps interface would > > > get the packet onto the wire faster hence it would arrive sooner than the > > > 10Mbps interface which would probably still be putting the data on the > >wire. > > > Correct? > > > > > > Tim > > > > > > - Original Message - > > > From: "Kevin L. Kultgen" <[EMAIL PROTECTED]> > > > Newsgroups: groupstudy.cisco > > > To: <[EMAIL PROTECTED]> > > > Sent: Wednesday, October 04, 2000 12:35 PM > > > Subject: Re: Ethernet Trivia > > > > > > > > > They would bith reach the destination at the same time (speed of > >electricity > > > through copper). The difference is in the rate at which the bits are > >placed > > > on the wire, the Fast Ethernet would be placing 20 bits of information > > > (actually encoded as 24 bits) on the wire for every 2 bits that the 10bT > > > would place on the wire. At least his is my understanding of 100bT vs > > > 10bT.. > > > > > > Anybody else have different(better?) interpretations? > > > > > > -- > > > Kevin L. Kultgen > > > > > > > > > ""Frank"" <[EMAIL PROTECTED]> wrote in message > > > 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]... > > > > Let&
Re: Ethernet Trivia
On Fri, 6 Oct 2000, Priscilla Oppenheimer wrote: > My brain hurts! &;-) My point was simply that on a short cable, the issue > of how much "space" a bit takes on the cable is irrelevant, n'est-ce pas?? Your brain hurts? I thought you were just getting to the point where you were going to tell us that given the maximum size of a 100bT and 10bT cable, what is the maximum amount of data that can be on that cable (assuming default MTU)..:) > > We all agree that serialization is the real issue. A 100Base-T port can > output bits 10 times as fast. > > By the way, I never saw my message posted. Did you? I haven't seen hardly > any of my messages posted lately. It's frustrating. > > Priscilla > > At 06:08 PM 10/6/00, Kevin L. Kultgen wrote: > >I'm not sure I stated my view properly. The first bits would get there at > >the same time but the last bits of 100bT would arrive wayyy before the last > >bits of the 10bT frame. The 100bT could send (almost) 10 frames in the same > >amount of time that the 10bT sent its one. > > > >I know Priscilla already has her CNX so she should be treated as a higher > >(final?) authority. > > > >Kevin L. Kultgen > > > >- Original Message - > >From: "Priscilla Oppenheimer" <[EMAIL PROTECTED]> > >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; "Tim O'Brien" > ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > >Sent: Friday, October 06, 2000 6:01 PM > >Subject: Re: Ethernet Trivia > > > > > > > Kevin, > > > > > > Great analysis. > > > > > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > > > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, > >or > > > 17.7 meters, in 10 Mbps Ethernet. > > > > > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > > > Ethernet. (I'm sure you figured that one out already.) > > > > > > It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to > > > make any difference! > > > > > > Priscilla > > > > > > At 10:12 AM 10/5/00, Kevin L. Kultgen wrote: > > > >They would both start at the same time. The 100bT interface would be > > > >placing bits on the wire faster than the 10bT interface and would > >complete > > > >placing bits on the wire in 1/10 the time. But those bits can't actually > > > >move any faster through the copper medium. The copper isn't more > >conductive > > > >(it's still Cat 5(e)) and the speed of light hasn't increased. So the > >bits > > > >that are placed on the wire will move through the wire at exactly the > >same > > > >rate. If the bits for 10bT consume 5 meters of cable megth before the > >NIC > > > >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > > > >before the next bit is placed on the wire. This is just an example, I'm > >not > > > >sure of the exact lengths of the bits on the wire, but the point is that > >the > > > >bits can't move any faster because the speed of electricity through > >copper > > > >is fixed. The difference is that the 100bT card is placing bits on the > >wire > > > >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits > >on > > > >the wire 100x faster than the 10bT card (or each bit would be .05 meters > >(5 > > > >centimeters), given the above example). > > > > > > > >So, on 100bT the end of the packet (the whole packet) would arrive before > > > >the 10bT would be done (in fact depending on the size of the packet 10bT > > > >might still be sending the preamble or headers), but the start of the > > > >packets (first bit of the preamble) would arrive at the same time. > > > > > > > >HTH, > > > > > > > >Thanx > > > > > > > >Kevin L. Kultgen > > > > > > > >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at > >one > > > >point how long a bit is on the wire but I forgot it. If I have anything > > > >that needs clarification (or correction) then please feel free to add it > >or > > > >request it. This is helping me too, because I'm looking at taking the > > > >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > > > &
Re: Ethernet Trivia
This makes it sound like there is actually something tangible being put on the wire. Bits are merely ones and zeros which are signaled by different voltages etc in the line encoding. Bits do not occupy line space. Measurements of how fast data can be moved over a wire are the time it takes for a signal at one end to be heard at the other. The amount of data (signals) which can be moved across a wire is ascertained by the line encoding method, and how many signals the encoding system can be made to produce in a second. Minus the delay factors between point A and B of course. I seem to recall reading some papers from folks at the US Berkley computer science dept a few years back that researched the various line encoding techniques etc that were quite interesting. I cannot find them now that I need them though!! BTW, my calculations for the speed of light resulted in 299,793,100 m/s - Original Message - From: Leigh Anne Chisholm <[EMAIL PROTECTED]> To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, October 06, 2000 4:15 PM Subject: RE: Ethernet Trivia > Ahh Kevin, your post reminds me of some research I did when I was putting together my paper on LAN Switching for CertificationZone. I was looking at how to calculate the round-trip propagation delay for 10BaseT networks. Here's a few technical numbers for you you (and possibly other Groupstudy members) might find interesting. > > --- Beginning of Calculations --- > > Electrical signals travel in a copper wire travel (propagate) at approximately two-thirds the speed of light. Remembering that the speed of 10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of wire that one bit occupies, by using the following calculation: > > Speed of Light in a Vacuum = 300,000,000 meters/second > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) occupies 10,240 meters of cable. > > --- End --- > > > -- Leigh Anne > > > > -Original Message- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > > Kevin L. Kultgen > > Sent: Thursday, October 05, 2000 10:12 AM > > To: Tim O'Brien; [EMAIL PROTECTED] > > Subject: Re: Ethernet Trivia > > > > > > They would both start at the same time. The 100bT interface would be > > placing bits on the wire faster than the 10bT interface and would complete > > placing bits on the wire in 1/10 the time. But those bits can't actually > > move any faster through the copper medium. The copper isn't more > > conductive > > (it's still Cat 5(e)) and the speed of light hasn't increased. > > So the bits > > that are placed on the wire will move through the wire at exactly the same > > rate. If the bits for 10bT consume 5 meters of cable megth before the NIC > > moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > > before the next bit is placed on the wire. This is just an > > example, I'm not > > sure of the exact lengths of the bits on the wire, but the point > > is that the > > bits can't move any faster because the speed of electricity through copper > > is fixed. The difference is that the 100bT card is placing bits > > on the wire > > 10x faster than the 10bT card. And 1000bT (gigabit ethernet) > > places bits on > > the wire 100x faster than the 10bT card (or each bit would be .05 > > meters (5 > > centimeters), given the above example). > > > > So, on 100bT the end of the packet (the whole packet) would arrive before > > the 10bT would be done (in fact depending on the size of the packet 10bT > > might still be sending the preamble or headers), but the start of the > > packets (first bit of the preamble) would arrive at the same time. > > > > HTH, > > > > Thanx > > > > Kevin L. Kultgen > > > > Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one > > point how long a bit is on the wire but I forgot it. If I have anything > > that needs clarification (or correction) then please feel free to > > add it or > > request it. This is helping me too, because I'm looking at taking the > > CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com). > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html >
Re: Ethernet Trivia
What you are describing is not the bit, it is the encoding. Bits are not actually on the wire. The actual bits of tangible data are only generated on the hosts at either end of the connection, and any internetworking device between links that needs to store or regenerate the signals. Everything in between is just signals. - Original Message - From: ElephantChild <[EMAIL PROTECTED]> To: whatshakin <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Saturday, October 07, 2000 1:18 AM Subject: Re: Ethernet Trivia > On Fri, 6 Oct 2000, whatshakin wrote: > > > This makes it sound like there is actually something tangible being put on > > the wire. Bits are merely ones and zeros which are signaled by different > > voltages etc in the line encoding. > > > > Bits do not occupy line space. > > Sorry. They do. > > A bit on the wire is a pulse or a series of pulses. > > As such, it has a leading edge, a trailing edge, and a duration. > > Both edges move through the wire at the speed of light in the material > the wire is made of. > > The length of the bit is the distance between the leading and trailing > edges. > > That distance is the speed of light multiplied by the duration of the > bit, or divided by the transmission speed in bits per second. > > (snip) > > > BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > That's in a hard vacuum. In metals and other good conductors, it's > usually between 1/2 and 2/3 that value. > > So yes, Virginia, there is a Santa^H^H^H^H^Hbit length. :-) > > -- > Bungee jumping and skydiving are for wimps. If you want to experience > true gut-wrenching terror, have children. --Dusty Rhoades. > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
On 7 Oct 2000 01:20:43 -0400, whatshakin <[EMAIL PROTECTED]> wrote: :This makes it sound like there is actually something tangible being put on :the wire. Bits are merely ones and zeros which are signaled by different :voltages etc in the line encoding. : :Bits do not occupy line space. Sure they do. Ever see the terms "wavelength" or "short wave" on a radio? Inversely proportional to the frequency, wave length is the physical length of a signal, based on the distance in free space for one cycle at a given frequency. As the speed of light is slower in media such as twisted pair copper and fiber, the length of a bit at a given frequency is shorter than it would be in free space. The ones and zeros obviously travel along the wire from the sending to the receiving end. If you could freeze time and take a snapshot, you would see a length of wire with a positive voltage, followed by one of negative charge, the lengths corresponding to bits. :Measurements of how fast data can be moved over a wire are the time it takes :for a signal at one end to be heard at the other. The amount of data :(signals) which can be moved across a wire is ascertained by the line :encoding method, and how many signals the encoding system can be made to :produce in a second. Minus the delay factors between point A and B of :course. And those delay factors are the speed-of-light propagation delay of the medium, the delay proportional to the length. Distance (length on the wire) equals velocity (speed of light in the medium) divided by time (length of a bit in fractions of a second). :BTW, my calculations for the speed of light resulted in 299,793,100 m/s Which method did you use? Laser and a spinning mirror? :-) -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
Comments inserted. - Original Message - From: Jay Hennigan <[EMAIL PROTECTED]> Newsgroups: groupstudy.cisco To: <[EMAIL PROTECTED]> Sent: Saturday, October 07, 2000 9:14 AM Subject: Re: Ethernet Trivia > On 7 Oct 2000 01:20:43 -0400, whatshakin <[EMAIL PROTECTED]> wrote: > > :This makes it sound like there is actually something tangible being put on > :the wire. Bits are merely ones and zeros which are signaled by different > :voltages etc in the line encoding. > : > :Bits do not occupy line space. > > Sure they do. Ever see the terms "wavelength" or "short wave" on a radio? > > Inversely proportional to the frequency, wave length is the physical length > of a signal, based on the distance in free space for one cycle at a given > frequency. As the speed of light is slower in media such as twisted pair > copper and fiber, the length of a bit at a given frequency is shorter than > it would be in free space. The physical length of a signal is not inversely proportional to its frequency. It differs depending on the line encoding. Again, a bit is the term applied to the signal state. Signal states occupy line space. > > The ones and zeros obviously travel along the wire from the sending to > the receiving end. If you could freeze time and take a snapshot, you > would see a length of wire with a positive voltage, followed by one of > negative charge, the lengths corresponding to bits. > This is quite a good hypothetical scenario, and is indeed correct. > :Measurements of how fast data can be moved over a wire are the time it takes > :for a signal at one end to be heard at the other. The amount of data > :(signals) which can be moved across a wire is ascertained by the line > :encoding method, and how many signals the encoding system can be made to > :produce in a second. Minus the delay factors between point A and B of > :course. > > And those delay factors are the speed-of-light propagation delay of the > medium, the delay proportional to the length. Distance (length on the wire) > equals velocity (speed of light in the medium) divided by time (length of > a bit in fractions of a second). > Your formula is correct, however, it does not apply very well to finding delay propogation over a wire because of the numerous other factors which need to be applied additionally. IE: The properties of the wire medium, EMF, block coding, IFG, protocol overhead... > :BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > Which method did you use? Laser and a spinning mirror? :-) Very observant! ;-) > > -- > Jay Hennigan - Network Administration - [EMAIL PROTECTED] > NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ > WestNet: Connecting you to the planet. 805 884-6323 > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
On 7 Oct 2000 14:23:15 -0400, whatshakin <[EMAIL PROTECTED]> wrote: :The physical length of a signal is not inversely proportional to its :frequency. It differs depending on the line encoding. Again, a bit is the :term applied to the signal state. Signal :states occupy line space. Point taken. This is the "bits vs. baud" issue. For straight serial signals where one bit = one baud such as Ethernet and T-1, they are equivalent. Ethernet relies on this for its collision detection mechanism. Perlman covers this quite well in Interconnections, Second Edition. See "Issues in 802.3" starting on page 35. :Your formula is correct, however, it does not apply very well to finding :delay propogation over a wire because of the numerous other factors which :need to be applied additionally. IE: The properties of the wire medium, :EMF, block coding, IFG, protocol overhead... The only property of the wire medium which is going to affect it is the propagation velocity factor. EMF is what makes it work at all. Protocol overhead won't affect the physical length of a signal element (bit on ethernet) within the medium. I don't know what IFG is but don't think that it's likely to change the laws of physics. -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
At 10:20 PM 10/6/00, whatshakin wrote: >This makes it sound like there is actually something tangible being put on >the wire. Bits are merely ones and zeros which are signaled by different >voltages etc in the line encoding. > >Bits do not occupy line space. Sure they do. Wasn't it Einstein that said time and distance are related? (Don't quote me on that.) Seriously, the discussion of how much space a bit takes on the wire has been going on since Ethernet was invented. See Optimized Engineering's Technical Compendium for a discussion that brings up the space issue. http://www.optimized.com/COMPENDI/EN-Propa.htm And here's some more related trivia. Do you know why a 32-bit jam is sent when a station detects a collision? It's to increase the time and distance of the collision event. It's to avoid the case where the collision happens right next to you and you've stopped transmitting by the time the collision event hits a repeater that could be 500 meters away. Why didn't they use a 16-bit jam? Because on thick coax Ethernet cable the signal travels at 231,000 kilometers per second. This means a bit occupies 23.1 meters on thick Ethernet. 16 x 23.1 wouldn't have been enough. 32 x 23.1 is 739 meters. An extension of 32 bits allows the sender to busy out a maximum 500-meter segment. This explains both the jam size and the fact that a repeater extends a received fragment by at least 32 bits. I know this is a strange way of looking at things, but it is one way that engineers, including the inventors of Ethernet, looked at the Ethernet parameters. Priscilla >Measurements of how fast data can be moved over a wire are the time it takes >for a signal at one end to be heard at the other. The amount of data >(signals) which can be moved across a wire is ascertained by the line >encoding method, and how many signals the encoding system can be made to >produce in a second. Minus the delay factors between point A and B of >course. > >I seem to recall reading some papers from folks at the US Berkley computer >science dept a few years back that researched the various line encoding >techniques etc that were quite interesting. I cannot find them now that I >need them though!! > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > >- Original Message - >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> >Sent: Friday, October 06, 2000 4:15 PM >Subject: RE: Ethernet Trivia > > > > Ahh Kevin, your post reminds me of some research I did when I was putting >together my paper on LAN Switching for CertificationZone. I was looking at >how to calculate the round-trip propagation delay for 10BaseT networks. >Here's a few technical numbers for you you (and possibly other Groupstudy >members) might find interesting. > > > > --- Beginning of Calculations --- > > > > Electrical signals travel in a copper wire travel (propagate) at >approximately two-thirds the speed of light. Remembering that the speed of >10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of >wire that one bit occupies, by using the following calculation: > > > > Speed of Light in a Vacuum = 300,000,000 meters/second > > > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) occupies >10,240 meters of cable. > > > > --- End --- > > > > > > -- Leigh Anne > > > > Priscilla Oppenheimer http://www.priscilla.com **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
This article is just another one which takes the complexities and puts them into nice laymans terms so the budding networkers of the world can understand them. - Original Message - From: Priscilla Oppenheimer <[EMAIL PROTECTED]> To: whatshakin <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Saturday, October 07, 2000 12:15 PM Subject: Re: Ethernet Trivia > At 10:20 PM 10/6/00, whatshakin wrote: > >This makes it sound like there is actually something tangible being put on > >the wire. Bits are merely ones and zeros which are signaled by different > >voltages etc in the line encoding. > > > >Bits do not occupy line space. > > Sure they do. Wasn't it Einstein that said time and distance are related? > (Don't quote me on that.) Seriously, the discussion of how much space a bit > takes on the wire has been going on since Ethernet was invented. See > Optimized Engineering's Technical Compendium for a discussion that brings > up the space issue. > > http://www.optimized.com/COMPENDI/EN-Propa.htm > > And here's some more related trivia. Do you know why a 32-bit jam is sent > when a station detects a collision? It's to increase the time and distance > of the collision event. It's to avoid the case where the collision happens > right next to you and you've stopped transmitting by the time the collision > event hits a repeater that could be 500 meters away. > > Why didn't they use a 16-bit jam? Because on thick coax Ethernet cable the > signal travels at 231,000 kilometers per second. This means a bit occupies > 23.1 meters on thick Ethernet. 16 x 23.1 wouldn't have been enough. 32 x > 23.1 is 739 meters. An extension of 32 bits allows the sender to busy out a > maximum 500-meter segment. This explains both the jam size and the fact > that a repeater extends a received fragment by at least 32 bits. > > I know this is a strange way of looking at things, but it is one way that > engineers, including the inventors of Ethernet, looked at the Ethernet > parameters. > > Priscilla > > > >Measurements of how fast data can be moved over a wire are the time it takes > >for a signal at one end to be heard at the other. The amount of data > >(signals) which can be moved across a wire is ascertained by the line > >encoding method, and how many signals the encoding system can be made to > >produce in a second. Minus the delay factors between point A and B of > >course. > > > >I seem to recall reading some papers from folks at the US Berkley computer > >science dept a few years back that researched the various line encoding > >techniques etc that were quite interesting. I cannot find them now that I > >need them though!! > > > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > > > > >- Original Message - > >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> > >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien > ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > >Sent: Friday, October 06, 2000 4:15 PM > >Subject: RE: Ethernet Trivia > > > > > > > Ahh Kevin, your post reminds me of some research I did when I was putting > >together my paper on LAN Switching for CertificationZone. I was looking at > >how to calculate the round-trip propagation delay for 10BaseT networks. > >Here's a few technical numbers for you you (and possibly other Groupstudy > >members) might find interesting. > > > > > > --- Beginning of Calculations --- > > > > > > Electrical signals travel in a copper wire travel (propagate) at > >approximately two-thirds the speed of light. Remembering that the speed of > >10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of > >wire that one bit occupies, by using the following calculation: > > > > > > Speed of Light in a Vacuum = 300,000,000 meters/second > > > > > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > > > > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > > > > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) occupies > >10,240 meters of cable. > > > > > > --- End --- > > > > > > > > > -- Leigh Anne > > > > > > > > > > > Priscilla Oppenheimer > http://www.priscilla.com > > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
Priscilla Oppenheimer wrote: > Does this help at all? Speed of light in twisted-pair cable is 177,000 > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or > 17.7 meters, in 10 Mbps Ethernet. > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > Ethernet. (I'm sure you figured that one out already.) Some people questioned "the math" above, I'm guessing because it seems to read that a bit travels 17.7 meters/sec in 10 Mb Ethernet. But we missed the "physics" issues to keep things equivalent. By dividing the 177,000 (or 200,000 as someone else suggested, or whatever) by 10M or 100M you do get a "bit length" on the media, but what was missed was you must also divide the time (1 sec) as well by 10M or 100M. This was alluded to in the "jam packet" discussion by Priscilla later on the 16 vs 32 bit jam signal. There were also some issues with thick ethernet (10Base5) where you could only 'tap' a segment every 2 meters (as I recall) so that you can detect a neighbor transmitting at/near the same time (the opposite extreme of the endpoints). As far as I know this was practically dropped with 10Base2 and totally dropped with 10BaseT. There was also a mention of IFG (InterFrame Gap) which is also time wise (and length-wise) related to bit/signal rate on the media. Thus the complex blend of physical laws, timing, performance, and other issues on the media. Geeez, I hate layer 1 stuff :-) Jeff Kell <[EMAIL PROTECTED]> **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
At 01:03 AM 10/8/00, Jeff Kell wrote: >Priscilla Oppenheimer wrote: > > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or > > 17.7 meters, in 10 Mbps Ethernet. > > > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > > Ethernet. (I'm sure you figured that one out already.) > >Some people questioned "the math" above, I'm guessing because it seems >to read that a bit travels 17.7 meters/sec in 10 Mb Ethernet. But >we missed the "physics" issues to keep things equivalent. No fuzzy math or physics is needed. We are dividing meters per second by bits per second, which is the same thing as meters/sec x sec/bit. Cancel out the seconds and you have meters per bit, in other words how much space on a cable a bit occupies. I was just sitting out on my deck on the last sunny day we will probably have for months in Oregon and realized that folks may be missing the basic arithmetic involved, though they understand the more complicated aspects. That's weird! Well, back to the sun! Priscilla Priscilla Oppenheimer http://www.priscilla.com **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia
Priscilla Oppenheimer wrote: > > At 01:03 AM 10/8/00, Jeff Kell wrote: > >Priscilla Oppenheimer wrote: > > > > > Does this help at all? Speed of light in twisted-pair cable is 177,000 > > > km/sec. So a bit occupies 177,000 divided by 10 million bits per second, or > > > 17.7 meters, in 10 Mbps Ethernet. > > > > > > 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps > > > Ethernet. (I'm sure you figured that one out already.) > > > >Some people questioned "the math" above, I'm guessing because it seems > >to read that a bit travels 17.7 meters/sec in 10 Mb Ethernet. But > >we missed the "physics" issues to keep things equivalent. > > No fuzzy math or physics is needed. We are dividing meters per second by > bits per second, which is the same thing as meters/sec x sec/bit. Cancel > out the seconds and you have meters per bit, in other words how much space > on a cable a bit occupies. > You bring back some fond memories -- I was privileged to hear retired Rear Admiral Grace Hopper speak on two occasions, during her later years when DEC was so savvy as to hire her as a consultant. One of her talents was the ability to make computing and communications seem real to others. During her days as a DEC spokesperson, she was known to hand out physical "bits". In the first talk I attended, she handed each of us short pieces of wire which she explained were "nanoseconds". In the next talk, she gave us plastic-wrapped packets of what appeared to be salt and pepper -- picoseconds, she exclaimed. Somewhere in my physical archives I still have both of these, and do treasure them, to the puzzlement of others... http://www.cs.yale.edu/homes/tap/Files/hopper-story.html > I was just sitting out on my deck on the last sunny day we will probably > have for months in Oregon and realized that folks may be missing the basic > arithmetic involved, though they understand the more complicated aspects. > That's weird! > Ahh, in a few months, we'll all be jealous of the great snow conditions. Then we can calculate the length of a bit on the cable of a chair lift! :-) Marty Adkins Email: [EMAIL PROTECTED] Mentor Technologies Phone: 410-280-8840 x3006 275 West Street, Plaza 70WWW: http://www.mentortech.com Annapolis, MD 21401 Cisco CCIE #1289 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia
Of course bits occupy line space. It's called wavelength. And bits aren't signalled by different voltages, in ethernet. They are signalled by a voltage change, from -1 to +1 or +1 to -1. Try doing a web search on Manchester encoding. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of whatshakin Sent: Saturday, October 07, 2000 12:20 AM To: [EMAIL PROTECTED] Subject: Re: Ethernet Trivia This makes it sound like there is actually something tangible being put on the wire. Bits are merely ones and zeros which are signaled by different voltages etc in the line encoding. Bits do not occupy line space. Measurements of how fast data can be moved over a wire are the time it takes for a signal at one end to be heard at the other. The amount of data (signals) which can be moved across a wire is ascertained by the line encoding method, and how many signals the encoding system can be made to produce in a second. Minus the delay factors between point A and B of course. I seem to recall reading some papers from folks at the US Berkley computer science dept a few years back that researched the various line encoding techniques etc that were quite interesting. I cannot find them now that I need them though!! BTW, my calculations for the speed of light resulted in 299,793,100 m/s - Original Message - From: Leigh Anne Chisholm <[EMAIL PROTECTED]> To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Friday, October 06, 2000 4:15 PM Subject: RE: Ethernet Trivia > Ahh Kevin, your post reminds me of some research I did when I was putting together my paper on LAN Switching for CertificationZone. I was looking at how to calculate the round-trip propagation delay for 10BaseT networks. Here's a few technical numbers for you you (and possibly other Groupstudy members) might find interesting. > > --- Beginning of Calculations --- > > Electrical signals travel in a copper wire travel (propagate) at approximately two-thirds the speed of light. Remembering that the speed of 10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of wire that one bit occupies, by using the following calculation: > > Speed of Light in a Vacuum = 300,000,000 meters/second > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) occupies 10,240 meters of cable. > > --- End --- > > > -- Leigh Anne > > > > -Original Message- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > > Kevin L. Kultgen > > Sent: Thursday, October 05, 2000 10:12 AM > > To: Tim O'Brien; [EMAIL PROTECTED] > > Subject: Re: Ethernet Trivia > > > > > > They would both start at the same time. The 100bT interface would be > > placing bits on the wire faster than the 10bT interface and would complete > > placing bits on the wire in 1/10 the time. But those bits can't actually > > move any faster through the copper medium. The copper isn't more > > conductive > > (it's still Cat 5(e)) and the speed of light hasn't increased. > > So the bits > > that are placed on the wire will move through the wire at exactly the same > > rate. If the bits for 10bT consume 5 meters of cable megth before the NIC > > moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters) > > before the next bit is placed on the wire. This is just an > > example, I'm not > > sure of the exact lengths of the bits on the wire, but the point > > is that the > > bits can't move any faster because the speed of electricity through copper > > is fixed. The difference is that the 100bT card is placing bits > > on the wire > > 10x faster than the 10bT card. And 1000bT (gigabit ethernet) > > places bits on > > the wire 100x faster than the 10bT card (or each bit would be .05 > > meters (5 > > centimeters), given the above example). > > > > So, on 100bT the end of the packet (the whole packet) would arrive before > > the 10bT would be done (in fact depending on the size of the packet 10bT > > might still be sending the preamble or headers), but the start of the > > packets (first bit of the preamble) would arrive at the same time. > > > > HTH, > > > > Thanx > > > > Kevin L. Kultgen > > > > Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at one > > point how long a bit is on the wire but I forgot it. If I have anything > > that needs clarification (or correction) then please feel
RE: Ethernet Trivia
Come to think of it, despite my last response, bits don't occupy space, at least not in theory. Manchester encoding, used in ethernet, signals a bit as a one or a zero depending on the instantaneous change in voltage from +1 to -1 or -1 to +1 volt. The time spent at a particular voltage is just that, time spent. The bit itself is signal with the voltage change, which in theory is instantaneous. Of course, in reality there is no such thing as a square wave. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of whatshakin Sent: Saturday, October 07, 2000 1:23 PM To: [EMAIL PROTECTED] Subject: Re: Ethernet Trivia Comments inserted. - Original Message - From: Jay Hennigan <[EMAIL PROTECTED]> Newsgroups: groupstudy.cisco To: <[EMAIL PROTECTED]> Sent: Saturday, October 07, 2000 9:14 AM Subject: Re: Ethernet Trivia > On 7 Oct 2000 01:20:43 -0400, whatshakin <[EMAIL PROTECTED]> wrote: > > :This makes it sound like there is actually something tangible being put on > :the wire. Bits are merely ones and zeros which are signaled by different > :voltages etc in the line encoding. > : > :Bits do not occupy line space. > > Sure they do. Ever see the terms "wavelength" or "short wave" on a radio? > > Inversely proportional to the frequency, wave length is the physical length > of a signal, based on the distance in free space for one cycle at a given > frequency. As the speed of light is slower in media such as twisted pair > copper and fiber, the length of a bit at a given frequency is shorter than > it would be in free space. The physical length of a signal is not inversely proportional to its frequency. It differs depending on the line encoding. Again, a bit is the term applied to the signal state. Signal states occupy line space. > > The ones and zeros obviously travel along the wire from the sending to > the receiving end. If you could freeze time and take a snapshot, you > would see a length of wire with a positive voltage, followed by one of > negative charge, the lengths corresponding to bits. > This is quite a good hypothetical scenario, and is indeed correct. > :Measurements of how fast data can be moved over a wire are the time it takes > :for a signal at one end to be heard at the other. The amount of data > :(signals) which can be moved across a wire is ascertained by the line > :encoding method, and how many signals the encoding system can be made to > :produce in a second. Minus the delay factors between point A and B of > :course. > > And those delay factors are the speed-of-light propagation delay of the > medium, the delay proportional to the length. Distance (length on the wire) > equals velocity (speed of light in the medium) divided by time (length of > a bit in fractions of a second). > Your formula is correct, however, it does not apply very well to finding delay propogation over a wire because of the numerous other factors which need to be applied additionally. IE: The properties of the wire medium, EMF, block coding, IFG, protocol overhead... > :BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > Which method did you use? Laser and a spinning mirror? :-) Very observant! ;-) > > -- > Jay Hennigan - Network Administration - [EMAIL PROTECTED] > NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ > WestNet: Connecting you to the planet. 805 884-6323 > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia
Lets not make this any more complicated than it needs to be. In the case of Manchester encoding you are right on, but there are many more different line encoding methods than Manchester. You are indeed correct about bits being wavelength. However, you don't seem to grasp that bits are just a nice friendly term to help folks understand the concepts. Bits are intangible until sequences of them are turned into characters and formed into strings which are then compiled into scripts which get parsed by a command interpreter blah blah blah. >From: "Ray Mosely" <[EMAIL PROTECTED]> >Reply-To: <[EMAIL PROTECTED]> >To: "whatshakin" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> >Subject: RE: Ethernet Trivia >Date: Mon, 9 Oct 2000 14:07:01 -0500 > >Of course bits occupy line space. It's called >wavelength. And bits aren't signalled by >different voltages, in ethernet. They are >signalled by a voltage change, from -1 to +1 >or +1 to -1. Try doing a web search on Manchester >encoding. > >-Original Message- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of >whatshakin >Sent: Saturday, October 07, 2000 12:20 AM >To: [EMAIL PROTECTED] >Subject: Re: Ethernet Trivia > > >This makes it sound like there is actually something tangible being put on >the wire. Bits are merely ones and zeros which are signaled by different >voltages etc in the line encoding. > >Bits do not occupy line space. > >Measurements of how fast data can be moved over a wire are the time it >takes >for a signal at one end to be heard at the other. The amount of data >(signals) which can be moved across a wire is ascertained by the line >encoding method, and how many signals the encoding system can be made to >produce in a second. Minus the delay factors between point A and B of >course. > >I seem to recall reading some papers from folks at the US Berkley computer >science dept a few years back that researched the various line encoding >techniques etc that were quite interesting. I cannot find them now that I >need them though!! > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > >- Original Message - >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> >Sent: Friday, October 06, 2000 4:15 PM >Subject: RE: Ethernet Trivia > > > > Ahh Kevin, your post reminds me of some research I did when I was >putting >together my paper on LAN Switching for CertificationZone. I was looking at >how to calculate the round-trip propagation delay for 10BaseT networks. >Here's a few technical numbers for you you (and possibly other Groupstudy >members) might find interesting. > > > > --- Beginning of Calculations --- > > > > Electrical signals travel in a copper wire travel (propagate) at >approximately two-thirds the speed of light. Remembering that the speed of >10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of >wire that one bit occupies, by using the following calculation: > > > > Speed of Light in a Vacuum = 300,000,000 meters/second > > > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) >occupies >10,240 meters of cable. > > > > --- End --- > > > > > > -- Leigh Anne > > > > > > > -Original Message- > > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > > > Kevin L. Kultgen > > > Sent: Thursday, October 05, 2000 10:12 AM > > > To: Tim O'Brien; [EMAIL PROTECTED] > > > Subject: Re: Ethernet Trivia > > > > > > > > > They would both start at the same time. The 100bT interface would be > > > placing bits on the wire faster than the 10bT interface and would >complete > > > placing bits on the wire in 1/10 the time. But those bits can't >actually > > > move any faster through the copper medium. The copper isn't more > > > conductive > > > (it's still Cat 5(e)) and the speed of light hasn't increased. > > > So the bits > > > that are placed on the wire will move through the wire at exactly the >same > > > rate. If the bits for 10bT consume 5 meters of cable megth before the >NIC > > > moves the the next bit then a bit for 100bT will be 1/2 meter (.5 >meters) > > > before the next bit is placed
RE: Ethernet Trivia
Them's fightin' words, but I'll ignore that. The discussion is an ethernet discussion, therefore Manchester encoding is the correct physical layer protocol to refer to. The discussion was reaching some rarefied levels, so I felt comfortable throwing in the encoding concepts. Bits are a mathematical concept. "Binary digits." In that sense, they are intangible, and not wavelength, as is any number concept. (I'm not really sure what you mean "bits being wavelength." That discussion was on bits occupying line space.) Bits arose as a discussion concepts when the definition of "get there" was called into question. If by "get there" we mean the arrival of the first tiny little iota of information, then 10BaseT and 100BaseT arrive at the same time. If by "get there" we mean usable information in the form of a packet or frame, then 100BaseT gets there first. Follow the thread, and I hope you will see that my comments fit in, just a day later than the weekend warriors. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Frank Wells Sent: Monday, October 09, 2000 3:38 PM To: [EMAIL PROTECTED] Subject: RE: Ethernet Trivia Lets not make this any more complicated than it needs to be. In the case of Manchester encoding you are right on, but there are many more different line encoding methods than Manchester. You are indeed correct about bits being wavelength. However, you don't seem to grasp that bits are just a nice friendly term to help folks understand the concepts. Bits are intangible until sequences of them are turned into characters and formed into strings which are then compiled into scripts which get parsed by a command interpreter blah blah blah. >From: "Ray Mosely" <[EMAIL PROTECTED]> >Reply-To: <[EMAIL PROTECTED]> >To: "whatshakin" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> >Subject: RE: Ethernet Trivia >Date: Mon, 9 Oct 2000 14:07:01 -0500 > >Of course bits occupy line space. It's called >wavelength. And bits aren't signalled by >different voltages, in ethernet. They are >signalled by a voltage change, from -1 to +1 >or +1 to -1. Try doing a web search on Manchester >encoding. > >-Original Message- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of >whatshakin >Sent: Saturday, October 07, 2000 12:20 AM >To: [EMAIL PROTECTED] >Subject: Re: Ethernet Trivia > > >This makes it sound like there is actually something tangible being put on >the wire. Bits are merely ones and zeros which are signaled by different >voltages etc in the line encoding. > >Bits do not occupy line space. > >Measurements of how fast data can be moved over a wire are the time it >takes >for a signal at one end to be heard at the other. The amount of data >(signals) which can be moved across a wire is ascertained by the line >encoding method, and how many signals the encoding system can be made to >produce in a second. Minus the delay factors between point A and B of >course. > >I seem to recall reading some papers from folks at the US Berkley computer >science dept a few years back that researched the various line encoding >techniques etc that were quite interesting. I cannot find them now that I >need them though!! > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > >- Original Message - >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> >Sent: Friday, October 06, 2000 4:15 PM >Subject: RE: Ethernet Trivia > > > > Ahh Kevin, your post reminds me of some research I did when I was >putting >together my paper on LAN Switching for CertificationZone. I was looking at >how to calculate the round-trip propagation delay for 10BaseT networks. >Here's a few technical numbers for you you (and possibly other Groupstudy >members) might find interesting. > > > > --- Beginning of Calculations --- > > > > Electrical signals travel in a copper wire travel (propagate) at >approximately two-thirds the speed of light. Remembering that the speed of >10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of >wire that one bit occupies, by using the following calculation: > > > > Speed of Light in a Vacuum = 300,000,000 meters/second > > > > Speed of Electricity in a Copper Cable = 200,000,000 meters/second > > > > 20,000,000 meters/second / 10,000,000 bits/second = 20 meters per bit > > > > The minimum size Ethernet frame consisting of 64 bytes (512 bits) >occupies >10,240 meters of cable. > > > >
RE: Ethernet Trivia
Apologies Ray, that came out a little more harsh than intended. This thread is getting way off topic, lets leave it at that. >From: "Ray Mosely" <[EMAIL PROTECTED]> >Reply-To: "Ray Mosely" <[EMAIL PROTECTED]> >To: "Frank Wells" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> >Subject: RE: Ethernet Trivia >Date: Mon, 9 Oct 2000 16:43:04 -0500 > >Them's fightin' words, but I'll ignore that. > >The discussion is an ethernet discussion, therefore >Manchester encoding is the correct physical layer >protocol to refer to. The discussion was reaching >some rarefied levels, so I felt comfortable throwing >in the encoding concepts. > >Bits are a mathematical concept. "Binary digits." >In that sense, they are intangible, and not wavelength, >as is any number concept. (I'm not really sure what >you mean "bits being wavelength." That discussion was >on bits occupying line space.) > >Bits arose as a discussion concepts when the definition >of "get there" was called into question. If by "get there" >we mean the arrival of the first tiny little iota of information, >then 10BaseT and 100BaseT arrive at the same time. If >by "get there" we mean usable information in the form >of a packet or frame, then 100BaseT gets there first. > >Follow the thread, and I hope you will see that my comments >fit in, just a day later than the weekend warriors. > > >-Original Message- >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of >Frank Wells >Sent: Monday, October 09, 2000 3:38 PM >To: [EMAIL PROTECTED] >Subject: RE: Ethernet Trivia > > >Lets not make this any more complicated than it needs to be. In the case >of >Manchester encoding you are right on, but there are many more different >line >encoding methods than Manchester. > >You are indeed correct about bits being wavelength. However, you don't seem >to grasp that bits are just a nice friendly term to help folks understand >the concepts. Bits are intangible until sequences of them are turned into >characters and formed into strings which are then compiled into scripts >which get parsed by a command interpreter blah blah blah. > > > >From: "Ray Mosely" <[EMAIL PROTECTED]> > >Reply-To: <[EMAIL PROTECTED]> > >To: "whatshakin" <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> > >Subject: RE: Ethernet Trivia > >Date: Mon, 9 Oct 2000 14:07:01 -0500 > > > >Of course bits occupy line space. It's called > >wavelength. And bits aren't signalled by > >different voltages, in ethernet. They are > >signalled by a voltage change, from -1 to +1 > >or +1 to -1. Try doing a web search on Manchester > >encoding. > > > >-Original Message- > >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > >whatshakin > >Sent: Saturday, October 07, 2000 12:20 AM > >To: [EMAIL PROTECTED] > >Subject: Re: Ethernet Trivia > > > > > >This makes it sound like there is actually something tangible being put >on > >the wire. Bits are merely ones and zeros which are signaled by different > >voltages etc in the line encoding. > > > >Bits do not occupy line space. > > > >Measurements of how fast data can be moved over a wire are the time it > >takes > >for a signal at one end to be heard at the other. The amount of data > >(signals) which can be moved across a wire is ascertained by the line > >encoding method, and how many signals the encoding system can be made to > >produce in a second. Minus the delay factors between point A and B of > >course. > > > >I seem to recall reading some papers from folks at the US Berkley >computer > >science dept a few years back that researched the various line encoding > >techniques etc that were quite interesting. I cannot find them now that >I > >need them though!! > > > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > > > > >- Original Message - > >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> > >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien > ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > >Sent: Friday, October 06, 2000 4:15 PM > >Subject: RE: Ethernet Trivia > > > > > > > Ahh Kevin, your post reminds me of some research I did when I was > >putting > >together my paper on LAN Switching for CertificationZone. I was looking >at > >how to calculate the round-trip propagation delay for 10BaseT network
OT: Ethernet Trivia
I'm looking at some of the study notes for CNX from www.optimized.com and I can answer most situations but there are two that confuse me: a) Significantly more than 8 bytes of "55" or "AA" hexadecimal data appended to the end. Four bytes get appended by the initial host (for local collisions) and 4 more by the repeater (for remote echoing). Would this be the second machine noticing the collision (later) and appending it's four bytes too? And how about the repeater coming back (for a total of 16 bytes)? B) Streaming "00" or "FF" patterns of hexadecimal data appended to the end. I have no clue. The closest I could come up with was that one book stated that the the jam signal was not defined as a / sequence and could be any sequence ie or . I've read two Ethernet books and they tend to skim over top collisions and don't go into any depth. Thanx -- Kevin L. Kultgen "Priscilla Oppenheimer" <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > At 10:20 PM 10/6/00, whatshakin wrote: > >This makes it sound like there is actually something tangible being put on > >the wire. Bits are merely ones and zeros which are signaled by different > >voltages etc in the line encoding. > > > >Bits do not occupy line space. > > Sure they do. Wasn't it Einstein that said time and distance are related? > (Don't quote me on that.) Seriously, the discussion of how much space a bit > takes on the wire has been going on since Ethernet was invented. See > Optimized Engineering's Technical Compendium for a discussion that brings > up the space issue. > > http://www.optimized.com/COMPENDI/EN-Propa.htm > > And here's some more related trivia. Do you know why a 32-bit jam is sent > when a station detects a collision? It's to increase the time and distance > of the collision event. It's to avoid the case where the collision happens > right next to you and you've stopped transmitting by the time the collision > event hits a repeater that could be 500 meters away. > > Why didn't they use a 16-bit jam? Because on thick coax Ethernet cable the > signal travels at 231,000 kilometers per second. This means a bit occupies > 23.1 meters on thick Ethernet. 16 x 23.1 wouldn't have been enough. 32 x > 23.1 is 739 meters. An extension of 32 bits allows the sender to busy out a > maximum 500-meter segment. This explains both the jam size and the fact > that a repeater extends a received fragment by at least 32 bits. > > I know this is a strange way of looking at things, but it is one way that > engineers, including the inventors of Ethernet, looked at the Ethernet > parameters. > > Priscilla > > > >Measurements of how fast data can be moved over a wire are the time it takes > >for a signal at one end to be heard at the other. The amount of data > >(signals) which can be moved across a wire is ascertained by the line > >encoding method, and how many signals the encoding system can be made to > >produce in a second. Minus the delay factors between point A and B of > >course. > > > >I seem to recall reading some papers from folks at the US Berkley computer > >science dept a few years back that researched the various line encoding > >techniques etc that were quite interesting. I cannot find them now that I > >need them though!! > > > >BTW, my calculations for the speed of light resulted in 299,793,100 m/s > > > > > >- Original Message - > >From: Leigh Anne Chisholm <[EMAIL PROTECTED]> > >To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien > ><[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > >Sent: Friday, October 06, 2000 4:15 PM > >Subject: RE: Ethernet Trivia > > > > > > > Ahh Kevin, your post reminds me of some research I did when I was putting > >together my paper on LAN Switching for CertificationZone. I was looking at > >how to calculate the round-trip propagation delay for 10BaseT networks. > >Here's a few technical numbers for you you (and possibly other Groupstudy > >members) might find interesting. > > > > > > --- Beginning of Calculations --- > > > > > > Electrical signals travel in a copper wire travel (propagate) at > >approximately two-thirds the speed of light. Remembering that the speed of > >10 Mbps Ethernet is 10,000,000 bits/second, we can determine the length of > >wire that one bit occupies, by using the following calculation: > > > > > > Speed of Light in a Vacuum = 300,000,000 meters/second > > > > > >
Re: OT: Ethernet Trivia
Both of them. I think! Frank wrote: > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
Trick question! The one that thinks happy thoughts! : D Casey >From: "Frank" <[EMAIL PROTECTED]> >Reply-To: "Frank" <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: OT: Ethernet Trivia >Date: Wed, 4 Oct 2000 11:09:03 -0500 >Received: from [208.32.175.78] by hotmail.com (3.2) with ESMTP id >MHotMailBBA4A4C2000FD820F3A2D020AF4E068B21; Wed Oct 04 09:26:00 2000 >Received: from localhost (mail@localhost)by groupstudy.com (8.9.3/8.9.3) >with SMTP id MAA23518;Wed, 4 Oct 2000 12:23:51 -0400 >Received: by groupstudy.com (bulk_mailer v1.12); Wed, 4 Oct 2000 12:12:07 >-0400 >Received: (from listserver@localhost)by groupstudy.com (8.9.3/8.9.3) id >MAA21617GroupStudy Mailer; Wed, 4 Oct 2000 12:12:06 -0400 >Received: (from news@localhost)by groupstudy.com (8.9.3/8.9.3) id >MAA21599GroupStudy Mailer; Wed, 4 Oct 2000 12:12:06 -0400 >From [EMAIL PROTECTED] Wed Oct 04 09:26:30 2000 >Path: not-for-mail >Newsgroups: groupstudy.cisco >Organization: GroupStudy.com Discussion Groups >Lines: 7 >Message-ID: <8rfksm$l2s$[EMAIL PROTECTED]> >NNTP-Posting-Host: michael.divineinterventures.com >NNTP-Posting-Date: 4 Oct 2000 16:12:06 GMT >X-Priority: 3 >X-MSMail-Priority: Normal >X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 >X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 >Sender: [EMAIL PROTECTED] > >Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same >sized >frame over the same type of media and over the same distance and neither >experience >a collision. Which will get to the destination first? > > >**NOTE: New CCNA/CCDA List has been formed. For more information go to >http://www.groupstudy.com/list/Associates.html >_ >UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html >FAQ, list archives, and subscription info: http://www.groupstudy.com >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
Good question! I would guess that they would both arrive at the destination at the same time. The difference would be that the 100Mbps packet would finish transmitting first. The difference in speed can't be propagation delay since it goes over the same media. So the difference in speeds should be that the 100Mbps link is using less time to signal 1s and 0s and less of a delay between each bit. > >Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same >sized >frame over the same type of media and over the same distance and neither >experience >a collision. Which will get to the destination first? > _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
I'm going to have to say that the answer to that is: The one that transmitts first! The question never said that they were transmitting at the same time and/or on the same physical segment. > >Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > >sized > >frame over the same type of media and over the same distance and neither > >experience > >a collision. Which will get to the destination first? > > > > > >**NOTE: New CCNA/CCDA List has been formed. For more information go to > >http://www.groupstudy.com/list/Associates.html > >_ > >UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > >FAQ, list archives, and subscription info: http://www.groupstudy.com > >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > _ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. > > Share information about yourself, create your own public profile at > http://profiles.msn.com. > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
Let's say we have a 2 lane and a 5 lane road, 2 cars travel at the same speed over those roads,and neither experiences traffic, which will do 100 miles first? --- Frank <[EMAIL PROTECTED]> wrote: > Let's say we have a 10Mbps and 100Mbps interface. > Both transmit the same > sized > frame over the same type of media and over the same > distance and neither > experience > a collision. Which will get to the destination > first? > > > **NOTE: New CCNA/CCDA List has been formed. For more > information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: > http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: > http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] __ Do You Yahoo!? Yahoo! Photos - 35mm Quality Prints, Now Get 15 Free! http://photos.yahoo.com/ **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
Frank wrote: > > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? The one on the 100MB interface. Hint: "Serialization delay" -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
Nnanna Obuba wrote: > > Let's say we have a 2 lane and a 5 lane road, 2 cars > travel at the same speed over those roads,and neither > experiences traffic, which will do 100 miles first? Not exactly. You're standing at the city limit sign entering Switchville. The lead cars of two 512-car motorcades arrive at the same instant on parallel one-lane roads. Both motorcades are bumper-to-bumper, traveling at the same speed. On motorcade Tenbit, each car is exactly ten times as long as the cars of motorcade Hundredbit. Which motorcade will be "in town" (the last car has crossed the city limit sign) first? This is due to "serialization delay". With any serial data stream, and Ethernet is a serial data stream even though it doesn't use a "Serial" interface, there is a fixed amount of time allocated to each bit of information. On 10-base-(whatever) Ethernet, it's 100 nanoseconds per bit (1/10,000,000 second). With 100-base-(whatever), it's 10 nanoseconds per bit. With T-1, it's 648 nanoseconds per bit. Even though both frames travel over the wire (or fiber, or microwave) at the speed of light in whatever medium is used, for the frame to "arrive" you have to take into account the length of time it takes for the bits to clock in, one by one, until the entire frame has arrived. > --- Frank <[EMAIL PROTECTED]> wrote: > > Let's say we have a 10Mbps and 100Mbps interface. > > Both transmit the same > > sized > > frame over the same type of media and over the same > > distance and neither > > experience > > a collision. Which will get to the destination > > first? -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
On Wed, 4 Oct 2000, Frank wrote: > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? the first frames in 2 identical streams should arrive at the same time. But after that 100Mbps will arrive faster because of a smaller Inter-frame gapI would think. Brian > > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > --- Brian Feeny, CCNP, CCDA [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
On Wed, 4 Oct 2000, Nnanna Obuba wrote: > Let's say we have a 2 lane and a 5 lane road, 2 cars > travel at the same speed over those roads,and neither > experiences traffic, which will do 100 miles first? Not exactly. You're standing at the city limit sign entering Switchville. The lead cars of two 512-car motorcades arrive at the same instant on parallel one-lane roads. Both motorcades are bumper-to-bumper, traveling at the same speed. On motorcade Tenbit, each car is exactly ten times as long as the cars of motorcade Hundredbit. Which motorcade will be "in town" (the last car has crossed the city limit sign) first? > --- Frank <[EMAIL PROTECTED]> wrote: > > Let's say we have a 10Mbps and 100Mbps interface. > > Both transmit the same > > sized > > frame over the same type of media and over the same > > distance and neither > > experience > > a collision. Which will get to the destination > > first? -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
On Wed, 4 Oct 2000, Frank wrote: > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? The one on the 100MB interface. Hint: "Serialization delay" -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OT: Ethernet Trivia
It all boils down to the interpretation of the word "arrive" in the proposed question. Does the first bit constitute arrival or the last bit? If it is the first bit, then they both arrive at the same time or whichever transmits first. If it is the last bit then of course the 100Mb will win the prize. I would say it is a trick question that is referring to the first bit to signify arrival. I'm pretty sure most everyone knows that a frame will complete transmission sooner on 100Mb media opposed to 10Mb. -Original Message- From: Bob Ferguson [mailto:[EMAIL PROTECTED]] Sent: Friday, October 06, 2000 8:50 AM To: [EMAIL PROTECTED] Subject: Re: OT: Ethernet Trivia Nnanna Obuba wrote: > > Let's say we have a 2 lane and a 5 lane road, 2 cars > travel at the same speed over those roads,and neither > experiences traffic, which will do 100 miles first? Not exactly. You're standing at the city limit sign entering Switchville. The lead cars of two 512-car motorcades arrive at the same instant on parallel one-lane roads. Both motorcades are bumper-to-bumper, traveling at the same speed. On motorcade Tenbit, each car is exactly ten times as long as the cars of motorcade Hundredbit. Which motorcade will be "in town" (the last car has crossed the city limit sign) first? This is due to "serialization delay". With any serial data stream, and Ethernet is a serial data stream even though it doesn't use a "Serial" interface, there is a fixed amount of time allocated to each bit of information. On 10-base-(whatever) Ethernet, it's 100 nanoseconds per bit (1/10,000,000 second). With 100-base-(whatever), it's 10 nanoseconds per bit. With T-1, it's 648 nanoseconds per bit. Even though both frames travel over the wire (or fiber, or microwave) at the speed of light in whatever medium is used, for the frame to "arrive" you have to take into account the length of time it takes for the bits to clock in, one by one, until the entire frame has arrived. > --- Frank <[EMAIL PROTECTED]> wrote: > > Let's say we have a 10Mbps and 100Mbps interface. > > Both transmit the same > > sized > > frame over the same type of media and over the same > > distance and neither > > experience > > a collision. Which will get to the destination > > first? -- Jay Hennigan - Network Administration - [EMAIL PROTECTED] NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/ WestNet: Connecting you to the planet. 805 884-6323 **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: OT: Ethernet Trivia
Depends on whether you are asking about the leading bit, or the whole frame. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Martin-Guy Richard Sent: Wednesday, October 04, 2000 11:21 AM To: [EMAIL PROTECTED] Subject: Re: OT: Ethernet Trivia Both of them. I think! Frank wrote: > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the same > sized > frame over the same type of media and over the same distance and neither > experience > a collision. Which will get to the destination first? > > **NOTE: New CCNA/CCDA List has been formed. For more information go to > http://www.groupstudy.com/list/Associates.html > _ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: OT: Ethernet Trivia
At 01:54 PM 10/11/00, Kevin L. Kultgen wrote: >I'm looking at some of the study notes for CNX from www.optimized.com and I >can answer most situations but there are two that confuse me: > >a) Significantly more than 8 bytes of "55" or "AA" hexadecimal data >appended to the end. If it's more than 8 bytes of 55s and AAs, there's something more seriously wrong than a collision, such as a jabbering transceiver, (which is rare these days). When a collision occurs, the protocol analyzer captures some bits from the closest transmitter and then some preamble bits from the collider. If I remember correctly, you won't see the jam or the added bits that a repeater adds to fragments. None of this is particularly relevant to a Cisco study list since Cisco recommends microsegmenting so that there are only a few devices sharing a collision domain. Cisco would like it best if you bought only switches, in which case each collision domain has only two participants: the switch port and the connected device. Full-duplex means there's no collision domain whatsoever. Also, keep in mind that a lot of the CNX material is written from the point of view of a protocol analyzer sitting on a shared coax piece of wire. Not really relevant to what we do today. Could you send these questions to a CNX list?? Check this site to see if there is such a thing: http://www.optimized.com/cnx/ Good luck! Priscilla >Four bytes get appended by the initial host (for local collisions) and 4 >more by the repeater (for remote echoing). Would this be the second machine >noticing the collision (later) and appending it's four bytes too? And how >about the repeater coming back (for a total of 16 bytes)? > >B) Streaming "00" or "FF" patterns of hexadecimal data appended to the end. > >I have no clue. The closest I could come up with was that one book stated >that the the jam signal was not defined as a / sequence and could be >any sequence ie or . > >I've read two Ethernet books and they tend to skim over top collisions and >don't go into any depth. > >Thanx >-- >Kevin L. Kultgen Priscilla Oppenheimer http://www.priscilla.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
O/T Ethernet trivia morphed to accolades for Admiral Hopper
Thanks for the interesting article, Marty. This was especially cool: "Admiral Grace Murray Hopper received many awards and commendations for her accomplishments. In 1969, she was awarded the first ever Computer Science Man-of-the-Year Award from the Data Processing Management Association." The first computer science man of the year was a woman! &;-) Priscilla At 11:07 PM 10/8/00, Marty Adkins wrote: >You bring back some fond memories -- I was privileged to hear retired >Rear Admiral Grace Hopper speak on two occasions, during her later years >when DEC was so savvy as to hire her as a consultant. One of her talents >was the ability to make computing and communications seem real to others. >During her days as a DEC spokesperson, she was known to hand out physical >"bits". In the first talk I attended, she handed each of us short pieces >of wire which she explained were "nanoseconds". In the next talk, she >gave us plastic-wrapped packets of what appeared to be salt and pepper >-- picoseconds, she exclaimed. > >Somewhere in my physical archives I still have both of these, and do >treasure them, to the puzzlement of others... >http://www.cs.yale.edu/homes/tap/Files/hopper-story.html Priscilla Oppenheimer http://www.priscilla.com **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Ethernet Trivia mostly, Need an EE's answer probably. [7:13199]
We all hear about max cable lengths for Ethernet. But is there a minimum? If the TX pair of one side connects to the RX pair of the other, then collisions, if any, happen at the ingress of the hub or switch in the buffer, or on the buffer of the nic if just using a really short cross over, is this right? I've looked and looked, and haven't been able to get an answer that says "the minimun length of a Category 5 100Base connection is x feet" even the spec seems to be silent on it. What am I missing in my knowledge of physics and electronics? p.s. My foot long patches between hosts and a hub don't seem to cause errors. I'll stick a sniffer in this week and see if I see any. I'm manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13199&t=13199 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13224]
I remember reading that it was 3 feet, but I can't give you a source on that. I'll hunt around. -Original Message- From: NY50TT To: [EMAIL PROTECTED] Sent: 7/21/01 12:48 PM Subject: Ethernet Trivia mostly, Need an EE's answer probably. [7:13199] We all hear about max cable lengths for Ethernet. But is there a minimum? If the TX pair of one side connects to the RX pair of the other, then collisions, if any, happen at the ingress of the hub or switch in the buffer, or on the buffer of the nic if just using a really short cross over, is this right? I've looked and looked, and haven't been able to get an answer that says "the minimun length of a Category 5 100Base connection is x feet" even the spec seems to be silent on it. What am I missing in my knowledge of physics and electronics? p.s. My foot long patches between hosts and a hub don't seem to cause errors. I'll stick a sniffer in this week and see if I see any. I'm manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13224&t=13224 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia mostly, Need an EE's answer probably. [7:13225]
I remember seeing 3 feet listed at the minimum also. Eugene ""Hire, Ejay"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > I remember reading that it was 3 feet, but I can't give you a source on > that. I'll hunt around. > > -Original Message- > From: NY50TT > To: [EMAIL PROTECTED] > Sent: 7/21/01 12:48 PM > Subject: Ethernet Trivia mostly, Need an EE's answer probably. [7:13199] > > We all hear about max cable lengths for Ethernet. But is there a > minimum? > If the TX pair of one side connects to the RX pair of the other, then > collisions, if any, happen at the ingress of the hub or switch in the > buffer, or on the buffer of the nic if just using a really short cross > over, > is this right? I've looked and looked, and haven't been able to get an > answer that says "the minimun length of a Category 5 100Base connection > is x > feet" even the spec seems to be silent on it. What am I missing in my > knowledge of physics and electronics? > > p.s. My foot long patches between hosts and a hub don't seem to cause > errors. I'll stick a sniffer in this week and see if I see any. I'm > manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13225&t=13225 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13232]
I do believe the shortest patch cord length for 10/100Base-T is 1 meter. -Original Message- From: NY50TT To: [EMAIL PROTECTED] Sent: 7/21/2001 12:48 PM Subject: Ethernet Trivia mostly, Need an EE's answer probably. [7:13199] We all hear about max cable lengths for Ethernet. But is there a minimum? If the TX pair of one side connects to the RX pair of the other, then collisions, if any, happen at the ingress of the hub or switch in the buffer, or on the buffer of the nic if just using a really short cross over, is this right? I've looked and looked, and haven't been able to get an answer that says "the minimun length of a Category 5 100Base connection is x feet" even the spec seems to be silent on it. What am I missing in my knowledge of physics and electronics? p.s. My foot long patches between hosts and a hub don't seem to cause errors. I'll stick a sniffer in this week and see if I see any. I'm manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13232&t=13232 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13233]
Got lots of "shortys" around our camp and never had any problems. 8 inch to be exact. -Original Message- From: Greene, Patrick [mailto:[EMAIL PROTECTED]] Sent: Saturday, July 21, 2001 11:44 PM To: [EMAIL PROTECTED] Subject: RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13232] I do believe the shortest patch cord length for 10/100Base-T is 1 meter. -Original Message- From: NY50TT To: [EMAIL PROTECTED] Sent: 7/21/2001 12:48 PM Subject: Ethernet Trivia mostly, Need an EE's answer probably. [7:13199] We all hear about max cable lengths for Ethernet. But is there a minimum? If the TX pair of one side connects to the RX pair of the other, then collisions, if any, happen at the ingress of the hub or switch in the buffer, or on the buffer of the nic if just using a really short cross over, is this right? I've looked and looked, and haven't been able to get an answer that says "the minimun length of a Category 5 100Base connection is x feet" even the spec seems to be silent on it. What am I missing in my knowledge of physics and electronics? p.s. My foot long patches between hosts and a hub don't seem to cause errors. I'll stick a sniffer in this week and see if I see any. I'm manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13233&t=13233 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13234]
A quick search of the IEEE 802.3 spec didn't turn up any matches for 1 m as being the minimum length for 10BaseT (nor even 10Base2). There is a reference in the document however in Section 14 - "Twisted Pair Medium Attachment Unit (MAU) and baseband medium, type 10BaseT" has a clause that indicates that the MAU has a characteristic that it provides for operating over "0 m to at least 100 m (328 ft.) of twisted pair without the use of a repeater". Now I might be interpreting this wrong, but I'd say that 10BaseT has no minimum length... -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Murphy, George Sent: Saturday, July 21, 2001 11:00 PM To: [EMAIL PROTECTED] Subject: RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13233] Got lots of "shortys" around our camp and never had any problems. 8 inch to be exact. -Original Message- From: Greene, Patrick [mailto:[EMAIL PROTECTED]] Sent: Saturday, July 21, 2001 11:44 PM To: [EMAIL PROTECTED] Subject: RE: Ethernet Trivia mostly, Need an EE's answer probably. [7:13232] I do believe the shortest patch cord length for 10/100Base-T is 1 meter. -Original Message- From: NY50TT To: [EMAIL PROTECTED] Sent: 7/21/2001 12:48 PM Subject: Ethernet Trivia mostly, Need an EE's answer probably. [7:13199] We all hear about max cable lengths for Ethernet. But is there a minimum? If the TX pair of one side connects to the RX pair of the other, then collisions, if any, happen at the ingress of the hub or switch in the buffer, or on the buffer of the nic if just using a really short cross over, is this right? I've looked and looked, and haven't been able to get an answer that says "the minimun length of a Category 5 100Base connection is x feet" even the spec seems to be silent on it. What am I missing in my knowledge of physics and electronics? p.s. My foot long patches between hosts and a hub don't seem to cause errors. I'll stick a sniffer in this week and see if I see any. I'm manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13234&t=13234 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet Trivia mostly, Need an EE's answer probably. [7:13252]
When the Receive and Transmit paths are distinct, I believe that there is no minimum length. NY50TT wrote: > > We all hear about max cable lengths for Ethernet. But is there a minimum? > If the TX pair of one side connects to the RX pair of the other, then > collisions, if any, happen at the ingress of the hub or switch in the > buffer, or on the buffer of the nic if just using a really short cross over, > is this right? I've looked and looked, and haven't been able to get an > answer that says "the minimun length of a Category 5 100Base connection is x > feet" even the spec seems to be silent on it. What am I missing in my > knowledge of physics and electronics? > > p.s. My foot long patches between hosts and a hub don't seem to cause > errors. I'll stick a sniffer in this week and see if I see any. I'm > manufacturing these 3 inch patch cables for my test. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13252&t=13252 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
