UDLD in cisco router

[Jonn cos]

Hi all,

Do we have udld support in routers ? can someone pls guide me if we have this feature available on cisco routers ?                   

[Leo Laohoo]

Do we have udld support in routers ? can someone pls guide me if we have this feature available on cisco routers ?

I don't think UDLD is supported in routers.

[M. G.]

UDLD is used to prevent STP loops, therefore it L2 protocol and it does not run on the L3 interfaces. If you have router with a switch ports on the router, then you might have it

[Collin Clark]

UDLD is a Layer 2 protocol that enables devices connected through fiber-optic or twisted-pair Ethernet cables to monitor the physical configuration of the cables and detect when a unidirectional link exists. It is not used to prevent STP loops. It is supported on some of the etherswitch daughter cards. I don't have any fiber terminating on the chassis SFP ports so I'm not sure if it's supported there.

[M. G.]

This document explains how the Unidirectional Link Detection (UDLD) protocol can help to prevent forwarding loops and blackholing of traffic in switched networks.

Cisco

Regards,

[Bhishma Khanna]

Hi Jonn,

Just to give some more information about UDLD, whenever the switch detects a unidirectional link in the layer 2 LAN switching environment, it prefers to block the port completly(send it to err-disabled) rather than allowing the unidirectional flow of information. It has no use in the layer 3 environment.

Thanks.