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Re: Problems connectivity GE on Foundry BigIron to Cisco 2950T
From: Elijah Savage <esavage () digitalrage org>
Date: Sun, 15 Jan 2006 19:11:44 -0500

Sam Stickland wrote:

Replying to my own email..

I've found some sites that suggest it's not possible to disable auto-negotiation on 1000Base-T since other operational parameters are negotiated including selection of the master clock signal. I was aware that flow control was negotiated, but not the clock signal.

Can anyone elaborate?


On Sun, 15 Jan 2006, Sam Stickland wrote:


On Sun, 15 Jan 2006, Paul G wrote:

----- Original Message ----- From: "Farrell,Bob" <bobf () studentsonly com>
To: "Randy Bush" <randy () psg com>; "David Hubbard" <dhubbard () dino hostasaurus com>
Cc: "Sam Stickland" <sam_ml () spacething org>; <nanog () nanog org>
Sent: Sunday, January 15, 2006 4:45 PM
Subject: RE: Problems connectivity GE on Foundry BigIron to Cisco 2950T

Cisco commands-

speed 1000
duplex full

the bigiron wants (iirc):

spe 1000-full

i strongly suggest you peruse the cli reference for both devices.

On the foundry GBIC blades you can't configure the speed and duplex settings, they only support 1000-full.

(config-if-e1000-1/2)#speed-duplex 1000-full
Error - can't change speed and duplex mode

I've dug through as much information as I can about the cisco 2950T and 802.3z/802.3ab and disabling the auto-negiation. There appears to be no command at all available to do this.

The cabling arrangement is:

Foundry -- Straight -- Patch -- Underfloor -- Patch -- Crossover -- Cisco
GBIC       Cable      Panel     Straight     Panel      Cable

If I replace the final crossover cable with a straight, change the foundry to a 10/100 port, and plug the final end into a host NIC instead of the cisco I get a connection. Crossover cable has been changed twice now, and the RJ45 GBIC was previously working in a cisco 6500.

I am extensively familar (at least I believe I am) with both these models, and this one has me stumped.

If nobody else can see any configuration errors I guess I'm down to hardware issues.


Cisco Infrastructure Port Recommendation

Configuring auto-negotiation is much more critical in a GE environment than in a 10/100 environment. In fact, auto-negotiation should only be disabled on switch ports that attach to devices not capable of supporting negotiation, or where connectivity issues arise from interoperability issues. Cisco recommends that Gigabit negotiation be enabled (default) on all switch-to-switch links and generally all GE devices. The default value on Gigabit interfaces it auto-negotiation, but is still a good general practice to issue the following command to insure that auto-negotiation is enabled:

switch(config)#interface <type> <slot/port>
switch(config-If)#no speed

!--- Sets the port to auto-negotiate Gigabit parameters.

I have not looked at the RFC in a while but I thought when it first came out that auto negotiation had to be used on GigE.

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