Cisco Support Community
Community Member

No link on cat3550

We changed our Cat3524XL switches for Cat3550-48 switches.

As mentioned the STP problem we upgraded the 3550 to IOS 12.1(11)EA1.

When we moved the workstations from the 3524XL to the 3550 we noticed the following: When both link partners NIC and switchport are configured for 100Mb full duplex the link comes up, but when booting the workstation the link goes down and doesn't come up anymore. When we configure auto speed and auto duplex on both sides every thing goes ok.

Has anybody an idea what is going wrong when configured for fixed port settings?

T.i.a. Carlo.


Re: No link on cat3550

Take a look at this link:

It goes into reasons why and with different manufacturers.

Hope it helps.


Community Member

Re: No link on cat3550

I have visit this site before, the strange thing is it happens on different kinds of NICs but not all kinds. And it worked fine when they were connected to 3524 switches. I connected a so called NetTool from Fluke between a station and the 3550. It seems that the pulse level is drawn down on the NIC side when both are set to fixed 100Mb full duplex.

CreatePlease to create content