nexus 7000 ; interface isn't coming after once telco gave loop

[gavin han]

Hi,

we are bringing up new ckt and nexus 7000's interface isn't coming up once telco gave a loop. and wee following msg when I do "sh int eth1/1".

(UDLD Tx Rx loop, port: error)

what does "(UDLD Tx Rx loop, port: error)" it mean?

before loop. interface was showing as "Link not Connected".

[Leo Laohoo]

UDLD means Uni-Directional Link Detection.

Try disabling the port, remove UDLD and re-enabling it. 

[allan.thomas]

Hi,

UDLD is simply used for Unidirectional Link Detection, in most cases it used in order to ensure a loop free topology. In some circumstance the optical media could work in only one direction, thus STP for example could transition to forwarding state on the designated port as BPDUs could have been lost thus instigating a loop. See the follow link describing UDLD.

http://www.cisco.com/en/US/docs/switches/datacenter/sw/5_x/nx-os/interfaces/configuration/guide/if_basic.html#wp2266322

The question is what do you have end to end via the carrier? Do you need UDLD on the switch port?

Regards
Allan

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