Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Strange Cat5500 problem

I have a Catalyst 5500 with three 10/100 line cards. Some of these 10/100 ports are connected to Unix boxes. My configuration on the 5500 is to auto negotiate the link speed and suplex settings. The Unix boxes are set to negotiate the link and duplex also and they have 10/100 cards in them. This works fine, until the 5500 is restarted and then the ports connecting the Unix boxes auto negotiate to 10mb half duplex. The only way to solve this is to change all the ports to 100mb full duplex, then set them to auto?

Any ideas why the switch is losing its config?



Re: Strange Cat5500 problem


Think we going to have to start mailing each other offline at this rate.:))

Firstly did you perhaps try the MLS..??? i have ot had time to test it as yet, i might be some time tomorrow or next week.

As for this port negotiation. There are known problems with autonegotiation with certain NIC's, this is due to incorrect implememtation of 802.3u standard and FLP (Fast Link Pulse). Thus the reason for when hard coding to 100 the port comes up, there are also some bugs.


CSCdm51653 - Fixed in version 4.5(3), 5.1(2a)

Auto-negotiation between Sun 10/100 NICs and certain Catalyst 5000 family modules (such as the WS-X5225R) might result in speed and or duplex mismatches under certain conditions. The problem typically occurs after you reset the module or you disable and re-enable the switch port. The workaround is to disconnect and reconnect the cable connecting the workstation to the switch port.

If both the NIC and switch adhere to the IEEE 802.3u auto-negotiation specifications and all additional features are disabled, auto-negotiation should properly negotiate.


New Member

Re: Strange Cat5500 problem

Unless it is absolutely necessary to use auto-negotiate, I would hard set speed/duplex on both server and switch. As noted above, you can get unexpected and undesirable results. The enterprises I am familiar with do not auto-negotiate with server connections to the critical nature of these resources.