vlanTrunkPortDynamicStatus SNMP Trap

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Oct 24th, 2007
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We have a 6509 which is generating vlanTrunkPortDynamicStatus trap messages at irregular intervals (around 1 per day). The first trap shows the interface has changed to 'noTrunking' followed by another trap 6 seconds later with the status of 'trunking'.

The link it refers to is a alternate spanning-tree port. There are no corresponding messages in the log. Show interface shows no input/output errors.

Some days ago UDLD on the peer device set the state of its corresponding interface to err-disabled as it detected a receive/transmit loop. These traps have been sent prior to this and have continued after a shut/no shut was performed on the interface.

Any suggestions would be appreciated.



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bvsnarayana03 Wed, 10/24/2007 - 06:12
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If the peer doesnt recv any UDLD msg, then the port tends to be disabled.

Chk if there is unidirectional traffic on link. Is the port operational in full duplex. pls chk the cables also.

u may try this to chk bidirectional status:

sh udld interface#

gryphon55 Wed, 10/24/2007 - 06:37
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Thank you for your reply.

Data is being sent in both directions and UDLD is currently reporting the interface as bidirectional.

The link is provided by single-mode fibre (to a 4006 switch), the link traverses several ducts to reach the destination, making it virtually impossible to check every section of the fibre.

I guess these problems indicate a layer-1 issue? Bad connection/bad fibre or possibly bad GBIC?

Are there any further tests you can recommend?

Many thanks,


bvsnarayana03 Wed, 10/24/2007 - 06:59
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U may want to chk by replacing the cable before suspecting the module.

gryphon55 Wed, 10/24/2007 - 07:16
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That would be difficult since the cable is laid under roads and other public areas, especially since its not causing an outage.

Thanks for your help.


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