Re: Ethernet vs. Fast Ethernet [7:515]
Priscilla Oppenheimer wrote: > > At 06:12 PM 4/13/01, Irwin Lazar wrote: > > >I know a few years ago several interface cards, especially those from Intel, > >had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but I'd > >imagine these problems are resolved by now. (It shows you how long it has > >been since I've actually touched a real network. :-) ) > > Not much has changed! Auto-negotation seems to still be a disaster. We hear > complaints about it not working all the time. Does anyone have a technical > answer (or URL) that explains why it behaves so badly? Just trying to > learn. Thanks.. > I wouldn't go so far as to characterize it as a disaster, as it does usually work. More specifically, speed almost always negotiates or auto-senses correctly. And if it didn't, someone would investigate immediately and correct it. Duplex negotiation is done after the speed is set, and that sometimes incorrectly auto-negotiates. When that happens, everything does work, but there will be a performance impact that is totally dependent on the probability of simultaneous traffic in both directions. Hence, a workstation with a single-tasking user may not exhibit a symptom, while a server could be severely impacted. As others have mentioned here in previous posts, look for "late collisions" on the half-duplex side. Some specific reasons I know of or have experienced that cause autonegotiation to fail: a) Older drivers for 10/100 NICs that just didn't do it right -- I ran into this with the Compaq Netflex III. Updated driver solved it. b) Early 10/100 NICs based on the National Semiconductor DP83840 chip failed to negotiate duplex correctly, if the cable length was between 35-41 meters (a typical office length!). NatSemi corrected this flaw in the DP83840A version, but all the existing products were stuck with this limitation. Not only did this include some desktop NICs, but also some early Cat5000 blades. See CCO bug IDs CSCdj53500 and CSCdj53272. c) Say one side, the switch, is set for auto-negotiate, and the other side, a desktop, is set to 10/half. Everything negotiates fine. Now what if the desktop changes its setting on the fly to 100Mbps. The 100Mbps fast link pulses produce enough signal in the frequency band of the 10Mbps link pulses, such that the 10Mb side never sees a loss of signal, so it doesn't realize there is a need to re-negotiate! One way this happens is when the desktop O/S changes it while booting. Even more subtle and less noticed is if the speed doesn't change but the O/S changes the duplex. The fix is to have the O/S driver momentarily drop signal whenever speed or duplex are modified. I recall 3Com 3C905 PCI cards and their driver producing this symptom. Workaround: pull the cable out/in or cycle the port. See CCO bug ID CSCdk28412. If anyone would like to read more than you want to know about auto-negotation, read http://www.scyld.com/expert/NWay.html, written by Bill Bunch of National Semiconductor. NatSemi contributed the technique to 802.3u. If you want to read about conformance testing, including auto-negotiation, peruse: http://www.iol.unh.edu/testsuites/fe/index.html at http://www.iol.unh.edu/consortiums/fe/index.html If you're into hardware chipsets, then follow the links at: http://www.scyld.com/expert/100mbps.html And as a great place to start on anything about Ethernet, Charles Spurgeon's site at U. Texas is still great: http://wwwhost.ots.utexas.edu/ethernet/ Marty Adkins Email: [EMAIL PROTECTED] Mentor Technologies Phone: 240-568-6526 133 National Business Pkwy WWW: http://www.mentortech.com Annapolis Junction, MD 20701Cisco CCIE #1289 Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=659&t=515 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Ethernet vs. Fast Ethernet [7:515]
The switch port shoud be matched to the host nic. It does not matter if
port one is 10 and port two is 100 and port 3 is 10 and port 4 is 100. etc
etc etc.
Dom Marino
""Sammi"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> On 14 Apr 2001 00:41:57 -0400, [EMAIL PROTECTED] ("Circusnuts")
> wrote:
>
> >Lock it down on both side if necessary (speed 100, duplex full, etc.,
etc.).
> >Never let the switch or router IOS defaults make the decision for you (I
bet
> >Chuck could tell you this, having just taken the CCIE lab).
Autonegotiation
> >& especially the blue flamed hotswaps- do not exist in production.
>
> So configuring for 100 won't cause problems with 10 speed devices?
> Guess I should just check it out, but actually I'm thrashing as it is.
>
> Sitting here with two 2900xl switches, one 2800, one hub, a number of
> workstations, trying to figure the best strategy for productive
> learning.
>
> Wish I had a router, will try getting my hands on one.l
>
> Though just experimenting is a learning experience in itself.
> FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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Re: Ethernet vs. Fast Ethernet [7:515]
On 14 Apr 2001 00:41:57 -0400, [EMAIL PROTECTED] ("Circusnuts")
wrote:
>Lock it down on both side if necessary (speed 100, duplex full, etc., etc.).
>Never let the switch or router IOS defaults make the decision for you (I bet
>Chuck could tell you this, having just taken the CCIE lab). Autonegotiation
>& especially the blue flamed hotswaps- do not exist in production.
So configuring for 100 won't cause problems with 10 speed devices?
Guess I should just check it out, but actually I'm thrashing as it is.
Sitting here with two 2900xl switches, one 2800, one hub, a number of
workstations, trying to figure the best strategy for productive
learning.
Wish I had a router, will try getting my hands on one.l
Though just experimenting is a learning experience in itself.
Message Posted at:
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Re: Ethernet vs. Fast Ethernet [7:515]
Lock it down on both side if necessary (speed 100, duplex full, etc., etc.).
Never let the switch or router IOS defaults make the decision for you (I bet
Chuck could tell you this, having just taken the CCIE lab). Autonegotiation
& especially the blue flamed hotswaps- do not exist in production.
Cheers
Phil
- Original Message -
From: Sammi
To:
Sent: Saturday, April 14, 2001 12:18 AM
Subject: Re: Ethernet vs. Fast Ethernet [7:515]
> On 13 Apr 2001 18:45:28 -0400, [EMAIL PROTECTED] ("Priscilla
> Oppenheimer") wrote:
>
> >At 06:12 PM 4/13/01, Irwin Lazar wrote:
> >
> >>I know a few years ago several interface cards, especially those from
> Intel,
> >>had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but
I'd
> >>imagine these problems are resolved by now. (It shows you how long it
has
> >>been since I've actually touched a real network. :-) )
> >
> >Not much has changed! Auto-negotation seems to still be a disaster. We
hear
> >complaints about it not working all the time. Does anyone have a
technical
> >answer (or URL) that explains why it behaves so badly? Just trying to
> >learn. Thanks..
>
> In light of these difficulites, how does one compensate or work with
> it?
> FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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Re: Ethernet vs. Fast Ethernet [7:515]
On 13 Apr 2001 18:45:28 -0400, [EMAIL PROTECTED] ("Priscilla
Oppenheimer") wrote:
>At 06:12 PM 4/13/01, Irwin Lazar wrote:
>
>>I know a few years ago several interface cards, especially those from
Intel,
>>had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but I'd
>>imagine these problems are resolved by now. (It shows you how long it has
>>been since I've actually touched a real network. :-) )
>
>Not much has changed! Auto-negotation seems to still be a disaster. We hear
>complaints about it not working all the time. Does anyone have a technical
>answer (or URL) that explains why it behaves so badly? Just trying to
>learn. Thanks..
In light of these difficulites, how does one compensate or work with
it?
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RE: Ethernet vs. Fast Ethernet [7:515]
>At 06:12 PM 4/13/01, Irwin Lazar wrote: > >>I know a few years ago several interface cards, especially those from Intel, >>had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but I'd >>imagine these problems are resolved by now. (It shows you how long it has >>been since I've actually touched a real network. :-) ) > >Not much has changed! Auto-negotation seems to still be a disaster. We hear >complaints about it not working all the time. Does anyone have a technical >answer (or URL) that explains why it behaves so badly? Just trying to >learn. Thanks.. > >Priscilla Of Ethernet and Fast Ethernet, one is male and the other is female, although it is not clear which is which. The probability of automatic interoperability is left as an exercise to the reader. > > >>Irwin >> >>-Original Message- >>From: Sammi [mailto:[EMAIL PROTECTED]] >>Sent: Friday, April 13, 2001 5:42 PM >>To: [EMAIL PROTECTED] >>Subject: Ethernet vs. Fast Ethernet [7:515] >> >> >>Ok, very basic question, I apologize. >>I know 10/100 is ethernet/fast ethernet, but what is the compatibility >>issues? If you have a 10/100 device configured for ethernet (say a >>2900xl switch) will it only go at 100 if specifically configured for >>Fast Ethernet? >>I can't find any literature that clearly spells the distinctions and >>considerations. >>FAQ, list archives, and subscription info: >>http://www.groupstudy.com/list/cisco.html >>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] >>FAQ, list archives, and subscription info: >>http://www.groupstudy.com/list/cisco.html >>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > > > > >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] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=540&t=515 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet vs. Fast Ethernet [7:515]
At 06:12 PM 4/13/01, Irwin Lazar wrote: >I know a few years ago several interface cards, especially those from Intel, >had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but I'd >imagine these problems are resolved by now. (It shows you how long it has >been since I've actually touched a real network. :-) ) Not much has changed! Auto-negotation seems to still be a disaster. We hear complaints about it not working all the time. Does anyone have a technical answer (or URL) that explains why it behaves so badly? Just trying to learn. Thanks.. Priscilla >Irwin > >-Original Message- >From: Sammi [mailto:[EMAIL PROTECTED]] >Sent: Friday, April 13, 2001 5:42 PM >To: [EMAIL PROTECTED] >Subject: Ethernet vs. Fast Ethernet [7:515] > > >Ok, very basic question, I apologize. >I know 10/100 is ethernet/fast ethernet, but what is the compatibility >issues? If you have a 10/100 device configured for ethernet (say a >2900xl switch) will it only go at 100 if specifically configured for >Fast Ethernet? >I can't find any literature that clearly spells the distinctions and >considerations. >FAQ, list archives, and subscription info: >http://www.groupstudy.com/list/cisco.html >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] >FAQ, list archives, and subscription info: >http://www.groupstudy.com/list/cisco.html >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=530&t=515 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet vs. Fast Ethernet [7:515]
The default configuration for most devices is to auto-sense, that is if a 10/100 device is talking with another 10/100 device, they will sense that they are both capable of 100 Mpbs operation and then operate at the higher speed (they will also sense full/half duplex). Most NICs, routers and switches let you manually specificy speed and duplex if you so desire. I know a few years ago several interface cards, especially those from Intel, had a heck of a time auto negotiating with Cisco Catalyst 5xxx's, but I'd imagine these problems are resolved by now. (It shows you how long it has been since I've actually touched a real network. :-) ) Irwin -Original Message- From: Sammi [mailto:[EMAIL PROTECTED]] Sent: Friday, April 13, 2001 5:42 PM To: [EMAIL PROTECTED] Subject: Ethernet vs. Fast Ethernet [7:515] Ok, very basic question, I apologize. I know 10/100 is ethernet/fast ethernet, but what is the compatibility issues? If you have a 10/100 device configured for ethernet (say a 2900xl switch) will it only go at 100 if specifically configured for Fast Ethernet? I can't find any literature that clearly spells the distinctions and considerations. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=526&t=515 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Ethernet vs. Fast Ethernet [7:515]
hmmm I am not sure what your asking but in any case, most devices that are 10/100 do auto negotiate, meaning they can go 10 or 100. If you have a Cisco 2900x1 switch and you want your port to only do 10 (Ethernet) then you can set the port for that speed.( i.e turn auto negotiation off) Karl -Original Message- From: Sammi [mailto:[EMAIL PROTECTED]] Sent: Friday, April 13, 2001 5:42 PM To: [EMAIL PROTECTED] Subject: Ethernet vs. Fast Ethernet [7:515] Ok, very basic question, I apologize. I know 10/100 is ethernet/fast ethernet, but what is the compatibility issues? If you have a 10/100 device configured for ethernet (say a 2900xl switch) will it only go at 100 if specifically configured for Fast Ethernet? I can't find any literature that clearly spells the distinctions and considerations. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=525&t=515 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
