Redux - RE: Problems connectivity GE on Foundry BigIron to Cisco 2950T

Thu Jan 19 13:55:22 UTC 2006

Hi,

I've had a lot of emails asking me how I was getting on with this, so I 
figured I'd do a quick redux of the issues for the archives.

One of the main problem actually turned out to be a damaged strand in the 
CAT5e underfloor cabling, which meant that the connection would work at 
10/100, but not at 1000 (GE) because of the use of extra pairs on GE. So 
leaving comments about castrating the cabling the engineer who assured me 
it had tested fine aside ;) the other problems we encountered were:

Foundry's GE auto-negotiation seems very tempermental.

Another engineer here just told there's a connection (on SX/MM) between a 
Foundry BigIron and clients Dell switch in the network where both ends 
only get a link light when the Foundry is configured to neg-full-auto 
(Autonegotiation first, if failed try non-autonegotiation). auto-gig 
(Autonegotiation) and neg-off (Non-autonegotiation) don't work! Only 
neg-full-auto on which the connection is fine and stable.

We ditched the copper GBIC and used a 1000Base-SX to 1000Base-TX 
convertor. The foundry won't form a real link (from a fixed SX/SC blade) 
with the 1000Base-SX convertor until "gig-default auto-gig" is entered. 
With the default settings both ends get a link light but the Foundry never 
sees any mac-addresses.

The cisco 2950T does support auto MDI/MDI-X on the gigabit copper ports 
dispite this not being mentioned in the any switch specification I could 
find. I never did have any luck with a GE cross-over cable (even not using 
the damaged underfloor cabling).

Dispite never being able to get a link-light between the Foundry Copper 
GBIC and the cisco 2950T, I've since found another point in our network, 
using exactly the same model GBIC in this configuration, that's working 
fine. The GBIC has since been placed back into a cisco 6500 where it's 
working fine (hooked at to a 10/100/1000 port on another cisco 6500).

So, multi-vendor Copper GE - not always as easy as it sounds!

Sam

On Mon, 16 Jan 2006 sam_ml at spacething.org wrote:

>
> Hopefully the cisco copper GBIC supports Auto-MDI though, so a straight cable 
> should be good.
>
> S
>
> On Sun, 15 Jan 2006, David Prall wrote:
>
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>> GigE 1000Base-T requires all 4 pairs of wire. Auto-MDI is not supported on 
>> the 2950 series, so it won't handle this automagically. I would test with 
>> speed set to 100 if the foundry can support 10/100/1000 with the Copper 
>> GBIC. Put the two next to each other and test with 1000Base-T crossover 
>> cable, removing all the extra stuff if that doesn't work.
>> 
>> 1000Base-T requires that pairs 1 and 4 are also crossed along with 2 and 3.
>> http://en.wikipedia.org/wiki/Crossover_cable
>> 
>> David
>> 
>> - --
>> David C Prall dcp at dcptech.com http://dcp.dcptech.com
>> 
>> 
>>> -----Original Message-----
>>> From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On
>>> Behalf Of Mark Smith
>>> Sent: Sunday, January 15, 2006 5:44 PM
>>> To: Randy Bush
>>> Cc: dhubbard at dino.hostasaurus.com; sam_ml at spacething.org;
>>> nanog at nanog.org
>>> Subject: Re: Problems connectivity GE on Foundry BigIron to
>>> Cisco 2950T
>>> 
>>> 
>>> Hi Randy,
>>> 
>>> On Sun, 15 Jan 2006 11:10:04 -1000
>>> Randy Bush <randy at psg.com> wrote:
>>> 
>>>> 
>>>>> You are using a crossover cable right?
>>>>>> I'm having a right mare trying to get a Foundry BigIron to
>>>>>> connect up to a cisco 2950T, via Gigabit copper.
>>>> 
>>>> i was under the impression that gige spec handled crossover
>>>> automagically
>>>> 
>>> 
>>> According to "Ethernet, The Definitive Guide", that feature is an
>>> optional part of the spec.
>>> 
>>> One thing I've heard people encounter is that if they use a cross-over
>>> cable, which probably really implies a 100BASE-TX cross-over, then the
>>> ports only go to 100Mbps. A Gig-E rated straight through, in
>>> conjunction
>>> with the automatic crossover feature, was necessary to get to GigE.
>>> 
>>> Regards,
>>> Mark.
>>> 
>>> --
>>> 
>>>         "Sheep are slow and tasty, and therefore must remain
>>> constantly
>>>          alert."
>>>                                    - Bruce Schneier, "Beyond Fear"
>>> 
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>