How can I diag trunk issues on 3650 to Nortel switch

whiteford · ‎02-16-2009

Hi,

I have a Cisco 3650 switch and port 24 is trunked to a Nortel baystack switch. Every 2-4 weeks this trunk will go down and "show interface brief" it shows the port is down. If I do a "shutdown" on the port and then "no shutdown" the trunk comes back up.

There is no management on the Nortel so I can't remote into it. It's out of the box, plus this is a remote site in Scotland! :)

Can do anything else?

Giuseppe Larosa · ‎02-16-2009

Hello Andy,

the symptoms you have described point to some form of error disable.

To understand why the port has gone in error disable you need to examine the device log with

sh log | inc 0/24

possible reasons can be a link flapping, UDLD just to mention two

Hope to help

Giuseppe

whiteford · ‎02-17-2009

Hi,

Somebody rebooted the switch before asking me, so I get:

sh log | inc 0/24

00:00:30: %LINK-3-UPDOWN: Interface FastEthernet0/24, changed state to up

00:00:34: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to up

Would I get me if it wasn't rebooted?

Giuseppe Larosa · ‎02-17-2009

Hello Andy,

yes but if the switch exports syslog messages to a syslog server you can find them there in the file for this device.

Hope to help

Giuseppe

whiteford · ‎03-02-2009

Got the error!

1w6d: %PM-4-ERR_DISABLE: loopback error detected on Fa0/24, putting Fa0/24 in err-disable state