Re: port/duplex configs [7:69582]
ian williams 5/27/03 10:29:21 AM >>> >I have always configured ports on CAT switch to 100/full manually instead of >AUTO. >What is recommended when asked this question for the CCIE written. Should >both the end >device ( NIC ) and switch both be configured to 100/FULL? I can't imagine why such a question would be asked on any exam since the correct answer is that you configure whatever is necessary to establish a connection with the end device. In my opinion, you should always use AUTO unless this causes problems, in which case you hard-set your devices to 100/HALF, not 100/FULL. If you'd like the rationale for that I refer you to the archives for my previous rantings on this subject. I'd fall over in shock if you were to be asked a question like this on your exam, but as long as you understand the issues involved you should be adequately prepared for whatever question of this type that they throw at you. Regards, John Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69593&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: port/duplex configs [7:69582]
This has come up in the ccie written. If I understand this subject correctly AUTO , sends out packets to try and match the 2 devices up with regards to speed and duplex. If your getting connection problems this would be a speed issue. If its some sort of packet loss/error then this could be a duplex problem. I have always configured the CAT port manually so there isnt any problems. Why would you choice AUTO? - Original Message - From: "John Neiberger" To: Sent: Tuesday, May 27, 2003 5:35 PM Subject: Re: port/duplex configs [7:69582] > >>>> ian williams 5/27/03 10:29:21 AM >>> > >I have always configured ports on CAT switch to 100/full manually instead > of > >AUTO. > >What is recommended when asked this question for the CCIE written. Should > >both the end > >device ( NIC ) and switch both be configured to 100/FULL? > > I can't imagine why such a question would be asked on any exam since the > correct answer is that you configure whatever is necessary to establish a > connection with the end device. In my opinion, you should always use AUTO > unless this causes problems, in which case you hard-set your devices to > 100/HALF, not 100/FULL. If you'd like the rationale for that I refer you to > the archives for my previous rantings on this subject. > > I'd fall over in shock if you were to be asked a question like this on your > exam, but as long as you understand the issues involved you should be > adequately prepared for whatever question of this type that they throw at > you. > > Regards, > John Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69649&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: port/duplex configs [7:69582]
I have seen this too, and like Ian I would normally go with 100/Full manually configured on botht he Cat and the end device (obviously assuming both devices support this settings). In real life, I have often found that setting the cat to Auto will often lead to duplex / speed mismatches (especially with Sun kit) The only time I have made use of Auto is when I am not 100% sure if the end device support 100MB, some of our legacy printers are 10MB half duplex, and indeed a number of the 2511's are only 10MB too.] ian williams wrote: > > This has come up in the ccie written. > If I understand this subject correctly AUTO , sends out packets > to try and > match the 2 devices up with regards to speed and duplex. > If your getting connection problems this would be a speed > issue. If its some > sort of packet loss/error then this could be a duplex problem. > I have always configured the CAT port manually so there isnt > any problems. > > Why would you choice AUTO? > > > > - Original Message - > From: "John Neiberger" > To: > Sent: Tuesday, May 27, 2003 5:35 PM > Subject: Re: port/duplex configs [7:69582] > > > > >>>> ian williams 5/27/03 10:29:21 AM >>> > > >I have always configured ports on CAT switch to 100/full > manually instead > > of > > >AUTO. > > >What is recommended when asked this question for the CCIE > written. Should > > >both the end > > >device ( NIC ) and switch both be configured to 100/FULL? > > > > I can't imagine why such a question would be asked on any > exam since the > > correct answer is that you configure whatever is necessary to > establish a > > connection with the end device. In my opinion, you should > always use AUTO > > unless this causes problems, in which case you hard-set your > devices to > > 100/HALF, not 100/FULL. If you'd like the rationale for that > I refer you > to > > the archives for my previous rantings on this subject. > > > > I'd fall over in shock if you were to be asked a question > like this on > your > > exam, but as long as you understand the issues involved you > should be > > adequately prepared for whatever question of this type that > they throw at > > you. > > > > Regards, > > John > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69660&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: port/duplex configs [7:69582]
ian williams wrote: > This has come up in the ccie written. > If I understand this subject correctly AUTO , sends out packets to try and > match the 2 devices up with regards to speed and duplex. > If your getting connection problems this would be a speed issue. If its some > sort of packet loss/error then this could be a duplex problem. > I have always configured the CAT port manually so there isnt any problems. > > Why would you choice AUTO? This issue has been beat upon quite frequently as of late, ask Mr. Neiberger;) I'll give you a good reason why you might choose auto. Had a large customer who recently installed a 4507 with supIV and 48 port 10/100/1000 cards. The customer was seeing a very large number of input and CRC errors. They hardcoded the ports and tried differant ports and modules, no help. I suggested they try auto and wallah, all errors ceased. Try manual again and the errors reappear immediately. Dave > > > > - Original Message - > From: "John Neiberger" > To: > Sent: Tuesday, May 27, 2003 5:35 PM > Subject: Re: port/duplex configs [7:69582] > > > >>>>>>ian williams 5/27/03 10:29:21 AM >>> >>>>> >>>I have always configured ports on CAT switch to 100/full manually instead >> >>of >> >>>AUTO. >>>What is recommended when asked this question for the CCIE written. Should >>>both the end >>>device ( NIC ) and switch both be configured to 100/FULL? >> >>I can't imagine why such a question would be asked on any exam since the >>correct answer is that you configure whatever is necessary to establish a >>connection with the end device. In my opinion, you should always use AUTO >>unless this causes problems, in which case you hard-set your devices to >>100/HALF, not 100/FULL. If you'd like the rationale for that I refer you > > to > >>the archives for my previous rantings on this subject. >> >>I'd fall over in shock if you were to be asked a question like this on > > your > >>exam, but as long as you understand the issues involved you should be >>adequately prepared for whatever question of this type that they throw at >>you. >> >>Regards, >>John -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 "Government can do something for the people only in proportion as it can do something to the people." -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69687&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: port/duplex configs [7:69582]
I don't have enough time at the moment to explain this as well as I should. Do a quick search on autonegotiation in the archives and I have some recent postings that explain it better. here's the short version: The only connection method specific in the FastEthernet standard is AUTO. If you do anything other than AUTO you are out of spec and the behavior is not consistent. When you manually set your speed and duplex settings some devices disable autonegotiation (NWAY) entirely. Others still participate in NWAY but they only offer the configured settings. The problems occur when you connect two devices that use different methods. If you do, you're guaranteed to get a duplex mismatch. The side that completely disables NWAY will stick to your manual settings, 100/Full, for example. The other side, if it still participates in NWAY, will still expect an NWAY-capable device to be attached. Since it doesn't detect NWAY, it falls back to half duplex, and there's your mismatch. Cisco's newer switches--like the 6500s and 2950s--disable NWAY entirely if you manually set the speed and duplex. About 98% of the NICs in our environment use the other method, which almost guarantees failure if we don't use AUTO. If you're going to manually set your settings with newer switches, 100/Full is the absolute worst possible setting. If you want high speed with manual settings the best setting is 100/Half. That way, if connect two devices that behave differently, you'll still be okay when the NWAY-capable NIC falls back to half duplex. Cisco's older switches, like the 2900XL series, still participated in NWAY even if you used manual settings. So, if you have a 2924XL with manual settings that needs to be replaced and you replace it with a 2950-24 with the identical config, I wish you luck for you are about to learn all of this the same way I did. I used to be a radical anti-auto person until I got our 6513, 2948Gs, 2980Gs, and a bunch of 2950s. I've since changed my mind and I'm now a very pro-AUTO person. The real killer here is that most NICs will continue to report their manual settings regardless of their operational settings. If you manually set a PC NIC to 100/Full, many times it will continue to report full duplex even if it has fallen back to using half duplex. Perhaps later today I'll have more time and I can get into some more details. Regards, John >>> Troy Leliard 5/28/03 4:52:30 AM >>> I have seen this too, and like Ian I would normally go with 100/Full manually configured on botht he Cat and the end device (obviously assuming both devices support this settings). In real life, I have often found that setting the cat to Auto will often lead to duplex / speed mismatches (especially with Sun kit) The only time I have made use of Auto is when I am not 100% sure if the end device support 100MB, some of our legacy printers are 10MB half duplex, and indeed a number of the 2511's are only 10MB too.] ian williams wrote: > > This has come up in the ccie written. > If I understand this subject correctly AUTO , sends out packets > to try and > match the 2 devices up with regards to speed and duplex. > If your getting connection problems this would be a speed > issue. If its some > sort of packet loss/error then this could be a duplex problem. > I have always configured the CAT port manually so there isnt > any problems. > > Why would you choice AUTO? > > > > ----- Original Message - > From: "John Neiberger" > To: > Sent: Tuesday, May 27, 2003 5:35 PM > Subject: Re: port/duplex configs [7:69582] > > > > >>>> ian williams 5/27/03 10:29:21 AM >>> > > >I have always configured ports on CAT switch to 100/full > manually instead > > of > > >AUTO. > > >What is recommended when asked this question for the CCIE > written. Should > > >both the end > > >device ( NIC ) and switch both be configured to 100/FULL? > > > > I can't imagine why such a question would be asked on any > exam since the > > correct answer is that you configure whatever is necessary to > establish a > > connection with the end device. In my opinion, you should > always use AUTO > > unless this causes problems, in which case you hard-set your > devices to > > 100/HALF, not 100/FULL. If you'd like the rationale for that > I refer you > to > > the archives for my previous rantings on this subject. > > > > I'd fall over in shock if you were to be asked a question > like this on > your > > exam, but as long as you understand the issues involved you > should be > > adequately prepared for whatever question of this type that > they throw at > > you. > > > > Regards, > > John Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69690&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: port/duplex configs [7:69582]
I have long been a hard coder of duplex and speed especially with Sun's and various other equipment. Recently working with Wi-lan (U3) and Proxim (AP2500) wireless gear changed my mind. Lab testing with a Cisco 3550 resulted in the Proxim only working with 10/half or auto/auto. Anything else produced errors. The Wi-lan gear only does auto. Auto on everything was the only good solution. Bob -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of MADMAN Sent: Wednesday, May 28, 2003 8:46 AM To: [EMAIL PROTECTED] Subject: Re: port/duplex configs [7:69582] ian williams wrote: > This has come up in the ccie written. > If I understand this subject correctly AUTO , sends out packets to try and > match the 2 devices up with regards to speed and duplex. > If your getting connection problems this would be a speed issue. If its some > sort of packet loss/error then this could be a duplex problem. > I have always configured the CAT port manually so there isnt any problems. > > Why would you choice AUTO? This issue has been beat upon quite frequently as of late, ask Mr. Neiberger;) I'll give you a good reason why you might choose auto. Had a large customer who recently installed a 4507 with supIV and 48 port 10/100/1000 cards. The customer was seeing a very large number of input and CRC errors. They hardcoded the ports and tried differant ports and modules, no help. I suggested they try auto and wallah, all errors ceased. Try manual again and the errors reappear immediately. Dave > > > > - Original Message - > From: "John Neiberger" > To: > Sent: Tuesday, May 27, 2003 5:35 PM > Subject: Re: port/duplex configs [7:69582] > > > >>>>>>ian williams 5/27/03 10:29:21 AM >>> >>>>> >>>I have always configured ports on CAT switch to 100/full manually instead >> >>of >> >>>AUTO. >>>What is recommended when asked this question for the CCIE written. Should >>>both the end >>>device ( NIC ) and switch both be configured to 100/FULL? >> >>I can't imagine why such a question would be asked on any exam since the >>correct answer is that you configure whatever is necessary to establish a >>connection with the end device. In my opinion, you should always use AUTO >>unless this causes problems, in which case you hard-set your devices to >>100/HALF, not 100/FULL. If you'd like the rationale for that I refer you > > to > >>the archives for my previous rantings on this subject. >> >>I'd fall over in shock if you were to be asked a question like this on > > your > >>exam, but as long as you understand the issues involved you should be >>adequately prepared for whatever question of this type that they throw at >>you. >> >>Regards, >>John -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 "Government can do something for the people only in proportion as it can do something to the people." -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69697&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: port/duplex configs [7:69582]
I agree with dave 100%...our default on the campus is auto/auto... Larry Letterman Cisco Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of MADMAN Sent: Wednesday, May 28, 2003 8:46 AM To: [EMAIL PROTECTED] Subject: Re: port/duplex configs [7:69582] ian williams wrote: > This has come up in the ccie written. > If I understand this subject correctly AUTO , sends out packets to try > and match the 2 devices up with regards to speed and duplex. If your > getting connection problems this would be a speed issue. If its some > sort of packet loss/error then this could be a duplex problem. I have > always configured the CAT port manually so there isnt any problems. > > Why would you choice AUTO? This issue has been beat upon quite frequently as of late, ask Mr. Neiberger;) I'll give you a good reason why you might choose auto. Had a large customer who recently installed a 4507 with supIV and 48 port 10/100/1000 cards. The customer was seeing a very large number of input and CRC errors. They hardcoded the ports and tried differant ports and modules, no help. I suggested they try auto and wallah, all errors ceased. Try manual again and the errors reappear immediately. Dave > > > > - Original Message - > From: "John Neiberger" > To: > Sent: Tuesday, May 27, 2003 5:35 PM > Subject: Re: port/duplex configs [7:69582] > > > >>>>>>ian williams 5/27/03 10:29:21 AM >>> >>>>> >>>I have always configured ports on CAT switch to 100/full manually >>>instead >> >>of >> >>>AUTO. >>>What is recommended when asked this question for the CCIE written. >>>Should both the end device ( NIC ) and switch both be configured to >>>100/FULL? >> >>I can't imagine why such a question would be asked on any exam since >>the correct answer is that you configure whatever is necessary to >>establish a connection with the end device. In my opinion, you should >>always use AUTO unless this causes problems, in which case you >>hard-set your devices to 100/HALF, not 100/FULL. If you'd like the >>rationale for that I refer you > > to > >>the archives for my previous rantings on this subject. >> >>I'd fall over in shock if you were to be asked a question like this on > > your > >>exam, but as long as you understand the issues involved you should be >>adequately prepared for whatever question of this type that they throw >>at you. >> >>Regards, >>John -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 "Government can do something for the people only in proportion as it can do something to the people." -- Thomas Jefferson Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=69696&t=69582 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: port/duplex configs [7:69582]
ian williams wrote: > > This has come up in the ccie written. A question that asks whether you should use auto or manual is really on the CCIE written? Of course, you can't answer that under NDA ;-), but I agree with John that it would be a bad question. It's implementation dependent, with changes occuring with every new release of hardware! Now, a theory question on the CCIE would make sense, though. A theory question could determine if you know how CSMA/CD works, which is still surprisingly relevant on modern networks, partly because of the infamous duplex mismatch problems that refuse to go away. > If I understand this subject correctly AUTO , sends out packets > to try and > match the 2 devices up with regards to speed and duplex. Autonegotiation doesn't send out packets. It actually uses link pulses. Remember it is used to make the link operational. It happens before packets (frames) could be sent. I'll copy and paste some info on this topic from my book at the end of this message. It's a little boring, so I'll put it at the end. :-) > If your getting connection problems this would be a speed > issue. If its some Yes, if there's a speed mismatch, you won't even get a link light and you have to fix that. > sort of packet loss/error then this could be a duplex problem. Yes, a duplex mismatch problem is hard to troubleshoot because you do get a link light and all seems fine, even though it's not. Problems occur as the load increases. So here's where CSMA/CD comes in. The half duplex side listens before sending and defers to the other sender. It also listens for collisions while sending. It assumes that the link requires a sender to Carrier Sense (CS); that the link is Multiple Access (MA); and that Collision Detection (CD) while sending is important. Now the full duplex side assumes that each link partner has its own dedicated send path and that the link is not MA. So there's no need to do CS. It sends whenever it wants to! So the full duplex side may send while the half duplex is already sending. The half duplex side dutifully adheres to the rules of Collision Detection. If it receives while sending, it backs off, waits a random amount of time, and retransmists. It also reports a collision. The fact that it backed off in the middle of sending means that it left behind an errored frame. It's also likely that the errored frame is shorter than a legal Ethernet frame (64 bytes) and constitute a runt, although the collision could have happened after 64 bytes, so the result could be a late collision. So the full duplex side receives this truncated packet from the half duplex side and reports a CRC error and either a runt or late collision. In summary, a duplex mismatch problem causes: CRC, runt, and late collisions at the Full Duplex station Collisions at the Half Duplex station, as well as Deferrals > I have always configured the CAT port manually so there isnt > any problems. The problem with manual is that the port might not participate in autonegotiation. The other side will assume that its partner is so old that it doesn't do autonegotiation and hence must be 10/Half. That's what the standard says it should do. So you could have one side set to 10/Full manually, and the other side deciding that it should be 10/Half. And here are some of the gory details from Troubleshooting Campus Networks, published by Wiley in 2002: "With autonegotiation, an interface advertises its abilities and detects the abilities of the device on the other end of the cable, called the link partner. The partners exchange their information in a reliable, acknowledged fashion. Autonegotiation compares the two sets of abilities and decides which technology to use, based on a standard priority for technologies. Once the highest-performance common mode is determined, autonegotiation relinquishes control to the appropriate technology and becomes transparent until the connection is broken or reset. The IEEE 802.3 autonegotiation standard specifies that an interface advertises its abilities in link pulses that encode a 16-bit word of information known as the Link Code Word (LCW). An interface sends a series of link pulses called a Fast Link Pulse (FLP) burst. An FLP burst is a sequence of 10BaseT Normal Link Pulses (NLPs). Each FLP is composed of 33 pulse positions, with the 17 odd-numbered positions corresponding to clock pulses and the 16 even-numbered positions corresponding to data pulses. All clock positions must contain a link pulse, although data positions do not need to contain a link pulse. The presence of a link pulse in a data position represents a logical 1 and the lack of a link pulse represents a logical 0. To ensure flexibility, the LCW has a Selector Field that allows 32 different definitions of the Technology Ability field. Currently, Selector Field values are defined for IEEE 802.3, 802.5 and 802.9. The Technology Ability Field is defined relative to the Selector Field. For 802.3, a device advertise
RE: port/duplex configs [7:69582]
I would like to tell you about a problem I had in relation to this. In November last year, I rolled out a new building for my current employer. We are not a huge company, but it was around 600 ports using 100% Cisco gear. The challenge was, that on thursday night, I took delivery of the gear. Friday it had to be in the new building and working, as with all the servers, routers, firewall and etc (did I mention that we did an IP change that same night across the WAN) Any way, the sys admins, gave me 6 machines that were used here in our company to test with. I configured the ports, as 100MB full, no auto as some machines had problems with this. So with all 600 floor ports configured, machines were taken out of the box's and turned on. Only about 200 of the 600 machines got a network link up. I could not understand this. I spent around 40 minutes looking at the switch configs looking for error's. Just saw non active ports. By this time, the Regional manager was yelling and screaming. I told him to hang on, as I will get this sorted out soon (the sys admins were encouraging this guy as we dont get along, they dont know much outside of right clicking objects).. I played with the port settings on a handful of ports, set them back to auto, set others to 10mb. This was proving to work. The problem was, that the ghost image created by the sys admins, was not such a standard at all. In total, there were around 5 images in use out on the floor. All created back in the days when this company was using hubs. On some of the PC's, the network settings of the NIC, was set to 10mb/s, others were set to 100mb/s half dup...It was a nightmare. In the end, I got the network running fine, however I did look stupid for a period of time. WHilst I was getting the network running, the sys admins took the regional manager to breakfast to calm him down. They had a good chat about why this was my fault...Now days, those sys admins, only have 512kb/s access to the rest of the network as opposed to Gig E. Summary, get better sys admins. Sys admins must start to understand that there ghost images and your network need to work together. Hope this helps some of you. It has made me a better technician. John Sydney Australia -Original Message- From: John Neiberger [mailto:[EMAIL PROTECTED] Sent: Thursday, 29 May 2003 2:43 AM To: [EMAIL PROTECTED] Subject: Re: port/duplex configs [7:69582] I don't have enough time at the moment to explain this as well as I should. Do a quick search on autonegotiation in the archives and I have some recent postings that explain it better. here's the short version: The only connection method specific in the FastEthernet standard is AUTO. If you do anything other than AUTO you are out of spec and the behavior is not consistent. When you manually set your speed and duplex settings some devices disable autonegotiation (NWAY) entirely. Others still participate in NWAY but they only offer the configured settings. The problems occur when you connect two devices that use different methods. If you do, you're guaranteed to get a duplex mismatch. The side that completely disables NWAY will stick to your manual settings, 100/Full, for example. The other side, if it still participates in NWAY, will still expect an NWAY-capable device to be attached. Since it doesn't detect NWAY, it falls back to half duplex, and there's your mismatch. Cisco's newer switches--like the 6500s and 2950s--disable NWAY entirely if you manually set the speed and duplex. About 98% of the NICs in our environment use the other method, which almost guarantees failure if we don't use AUTO. If you're going to manually set your settings with newer switches, 100/Full is the absolute worst possible setting. If you want high speed with manual settings the best setting is 100/Half. That way, if connect two devices that behave differently, you'll still be okay when the NWAY-capable NIC falls back to half duplex. Cisco's older switches, like the 2900XL series, still participated in NWAY even if you used manual settings. So, if you have a 2924XL with manual settings that needs to be replaced and you replace it with a 2950-24 with the identical config, I wish you luck for you are about to learn all of this the same way I did. I used to be a radical anti-auto person until I got our 6513, 2948Gs, 2980Gs, and a bunch of 2950s. I've since changed my mind and I'm now a very pro-AUTO person. The real killer here is that most NICs will continue to report their manual settings regardless of their operational settings. If you manually set a PC NIC to 100/Full, many times it will continue to report full duplex even if it has fallen back to using half duplex. Perhaps later today I'll have more time and I can get into some more details. Regards, John >>> Troy Leliard 5/28/03 4:52:30 AM >>> I have seen this too, and like Ian I
RE: port/duplex configs [7:69582]
Alas, those sys admins. I love your way of putting it. (They know how to right click things but not much more. ;-) The thing that gets me is that they are sure that they know networking. Thanks for a helpful story. Priscilla John Brandis wrote: > > I would like to tell you about a problem I had in relation to > this. > > In November last year, I rolled out a new building for my > current employer. > We are not a huge company, but it was around 600 ports using > 100% Cisco > gear. The challenge was, that on thursday night, I took > delivery of the > gear. Friday it had to be in the new building and working, as > with all the > servers, routers, firewall and etc (did I mention that we did > an IP change > that same night across the WAN) > > Any way, the sys admins, gave me 6 machines that were used here > in our > company to test with. I configured the ports, as 100MB full, no > auto as some > machines had problems with this. So with all 600 floor ports > configured, > machines were taken out of the box's and turned on. Only about > 200 of the > 600 machines got a network link up. I could not understand > this. I spent > around 40 minutes looking at the switch configs looking for > error's. Just > saw non active ports. By this time, the Regional manager was > yelling and > screaming. I told him to hang on, as I will get this sorted out > soon (the > sys admins were encouraging this guy as we dont get along, they > dont know > much outside of right clicking objects).. > > I played with the port settings on a handful of ports, set them > back to > auto, set others to 10mb. This was proving to work. The problem > was, that > the ghost image created by the sys admins, was not such a > standard at all. > In total, there were around 5 images in use out on the floor. > All created > back in the days when this company was using hubs. On some of > the PC's, the > network settings of the NIC, was set to 10mb/s, others were set > to 100mb/s > half dup...It was a nightmare. > > In the end, I got the network running fine, however I did look > stupid for a > period of time. WHilst I was getting the network running, the > sys admins > took the regional manager to breakfast to calm him down. They > had a good > chat about why this was my fault...Now days, those sys admins, > only have > 512kb/s access to the rest of the network as opposed to Gig E. > > Summary, get better sys admins. Sys admins must start to > understand that > there ghost images and your network need to work together. Hope > this helps > some of you. It has made me a better technician. > > John > Sydney Australia > > > -Original Message- > From: John Neiberger [mailto:[EMAIL PROTECTED] > Sent: Thursday, 29 May 2003 2:43 AM > To: [EMAIL PROTECTED] > Subject: Re: port/duplex configs [7:69582] > > > I don't have enough time at the moment to explain this as well > as I should. > Do a quick search on autonegotiation in the archives and I have > some recent > postings that explain it better. here's the short version: > > The only connection method specific in the FastEthernet > standard is AUTO. > If you do anything other than AUTO you are out of spec and the > behavior is > not consistent. When you manually set your speed and duplex > settings some > devices disable autonegotiation (NWAY) entirely. Others still > participate > in NWAY but they only offer the configured settings. The > problems occur > when you connect two devices that use different methods. If > you do, you're > guaranteed to get a duplex mismatch. > > The side that completely disables NWAY will stick to your > manual settings, > 100/Full, for example. The other side, if it still > participates in NWAY, > will still expect an NWAY-capable device to be attached. Since > it doesn't > detect NWAY, it falls back to half duplex, and there's your > mismatch. > > Cisco's newer switches--like the 6500s and 2950s--disable NWAY > entirely if > you manually set the speed and duplex. About 98% of the NICs > in our > environment use the other method, which almost guarantees > failure if we > don't use AUTO. If you're going to manually set your settings > with newer > switches, 100/Full is the absolute worst possible setting. If > you want high > speed with manual settings the best setting is 100/Half. That > way, if > connect two devices that behave differently, you'll still be > okay when the > NWAY-capable NIC falls back to half duplex. > > Cisco's older switches, like the 2900XL series, still > participated in NWAY > even if you used
