06-19-2006 08:48 AM - edited 03-03-2019 01:03 PM
I was wondering if you can connect a Cat 3550 GBIC port(using ws-g5483) to a CAT 3750 10/100/1000 port as a trunk port. I have tried this setup, but it seems that there may be a speed/duplex issue. I never get a link light between the 3550 GBIC and the 3750, but do get connectivity between the same 3550 GBIC and a 2950 10/100/1000 port. Both the 3550 and the 3750 are set to auto negotiate the port speed.
06-19-2006 12:08 PM
Hello,
this is from cisco cat3550:
"You can configure interface speed on Fast Ethernet (10/100-Mbps) and Gigabit Ethernet (10/100/1000-Mbps) interfaces; you cannot configure speed on Gigabit Interface Converter (GBIC) interfaces. You can configure duplex mode on any Fast Ethernet or Gigabit Ethernet interfaces that are not set to autonegotiate; you cannot configure duplex mode on GBIC interfaces.
"
HTH,
Vlad
06-20-2006 10:47 AM
This still does not explain why the GBIC, which runs at 1000 MB by default (auto-negotiation) does not link up with a 10/100/1000 ethernet port which is set to aut-negotiate. Does the GBIC have to communicate with another GBIC?
06-22-2006 01:58 PM
You might try seeing what flow-control is set on both ends. To get a cat5000 supe with 5484 GBICs to work with a Dell switch with 5484 GBICs, and a 2950T (UTP 10/100/1000) to work with the Dell with a cisco 5483 1000BaseT gbic, I ended up having to play with these until the link would work.
e.g. try on both ends
conf t
int gi#/#
flowcontrol receive off
flowcontrol send off
(or whatever)
Also (you probably have checked this, but in case you haven't - and if this works with the 2950 I can't imagine why it wouldn't work with the 3550) verify you have all four pairs in your crossover cable correct -
1, 2 to 3, 6;
3, 6 to 1, 2;
4, 5 to 7, 8,
7, 8 to 4, 5
FWIW
John
06-22-2006 04:37 PM
Hi, 2950 and 3750 have different ASIC, so the behavior might not be the same. However, this sounds like the link negotiation issue, have you tried the following on the 3750:
speed nonegotiate
This should bring the link up.
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