Switch Port Falling out of Trunk mode

Unanswered Question
Nov 16th, 2007


There have been a couple instances (on difference 5509 switches) where a

switch port that is being configured as a trunk have fallen out and reverted back to it's native VLAN. When this occurs, the commands to configure the trunk port are no longer on the switch.

This has occurred on a trunk port configured for Dot1q and NONEGOTIATE as

well as a trunk port configured for ISL and ON.

We'd like to know if this is a known issue and if possible the cause.



I have this problem too.
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glen.grant Fri, 11/16/2007 - 18:03

Can't say i have ever heard that . Check bugtool for any bugs for the version you are using . One reason I don't like to force trunks on , I always let them negotiate the trunks . When you force them it will show as trunk even though the trunk may not be working correctly. Unless there is a reason you need to use ISL you might want to try dot1q . Make sure you aren't getting errors on those interfaces too.


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