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New Member

Crossover or not crossover for GBIC-T and 10/100/1000 ports?

1. 3550-T 10/100/1000 port to T-GBIC WS-G5482 in 3550-48.

These cables work(full duplex, speed 1Gb ):

a. 4 pair Cross-over(1,2<->3,6) (4,5<->7,8)

b. "Classic 10/100" 2 pair Cross-over(1,2<->3,6) (4,5,7,8 straight)

c. Straight (1,2,3,4,5,6,7,8 straight)

2. two 3550-T 10/100/1000 ports inbetween

These cables work(full duplex, speed 1Gb ):

a. 4 pair Cross-over(1,2<->3,6) (4,5<->7,8)

b. "Classic 10/100" 2 pair Cross-over(1,2<->3,6) (4,5,7,8 straight)

There is note about Auto-sense MDI-X in T-GBIC:

http://www.cisco.com/warp/public/cc/pd/si/casi/ca3550/prodlit/gbict_ds.htm

Can somebody clear this issue?

(Namely why classic crossover works with 3550 10/100/1000 ports... and if yes why not straight as it is with T-GBIC?)

  • Other Network Infrastructure Subjects
2 REPLIES
Bronze

Re: Crossover or not crossover for GBIC-T and 10/100/1000 ports?

Here's a link with information on when to use a straight/cross cable:

http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/1000gbic/instnote.htm

New Member

Re: Crossover or not crossover for GBIC-T and 10/100/1000 ports?

I'm preaty aware of your suggested shortcut.:)

Read the post again.

I wasn't asking which cable to use...

I was asking :

WHY IT WORKS?!!!!!?

because as you can see you don't need cross between switches to connect T-GBIC!!!

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