Problems connectivity GE on Foundry BigIron to Cisco 2950T

Mon Jan 16 00:24:35 UTC 2006

On Mon, 16 Jan 2006, Mark Smith wrote:

> On Sun, 15 Jan 2006 23:50:07 +0000 (GMT Standard Time)
> Sam Stickland <sam_ml at spacething.org> wrote:
>
>>
>> Hi,
>
> <snip>
>
>>
>> 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,
> Just do that ^^^ and give it a try.

Will do.

If that fails I might have to dig out a non-passive 1000SX to 1000-BaseT 
media convertor that's on one of the other sites and give that a try.

Btw, several people have suggested "speed nonegotiate" on the cisco speed. 
This command is only supported on GBIC slots on cisco, not on fixed 
1000Base-T interfaces (at least not a Sup720/WS-X6748-GE-TX).

I also found this reference about the clock signals in use on 1000Base-T:

"Synchronous transmission
1000BASE-T is based on synchronous transmission to facilitate the 
cancelation of Echo/NEXT/FEXT interferences at the receivers. To achieve 
synchronous transmission between the two PHYs at the ends of a link, a 
master-slave clocking relationship is established by the PHYs. The 
master-slave relationship between two stations sharing a link segment is 
established during auto-negotiation. The master PHY uses an external clock 
to determine the timing of transmitter and receiver operations. This 
master clock is also provided to the other stations in the network. The 
slave PHY recovers the clock from the received signal and uses it to 
determine the timing of transmitter operations. In a typical network, the 
PHY at the repeater will become the master and the PHY at the data 
terminal equipment (DTE) will become the slave."

So it would appear that auto-negotiation is a requirement in 1000Base-T.

Sam