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Is udld actually needed?

patoberli
VIP Alumni
VIP Alumni

Hello All

I wonder if udld on fibre links is really needed to be enabled or not.

Are there actually any benefits of enabling it in a completely fine running network?

We only use Cisco Switches here, from around 6 different series.

Thanks,

pato

4 Replies 4

smothuku
Level 7
Level 7

ankbhasi
Cisco Employee
Cisco Employee

Hi Pato,

Network is running fine and cross your finger it keep working fine but you never know when problem can come and cause some major issues.

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. All connected devices must support UDLD for the protocol to successfully identify and disable unidirectional links. When UDLD detects a unidirectional link, it disables the affected port and alerts you. Unidirectional links can cause a variety of problems, including spanning-tree topology loops.

So no problem in enabling UDLD.

Have a look at this link for more details

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12225see/scg/swudld.htm

HTH

Ankur

Thanks for the answers.

One more question, if I enable UDLD on one switch, would that cause any spanning-tree issues till I'd have it enabled on the connected switches?

Or can I simply enable it globally and nothing will happen?

Thanks,

pato

Hi Pato,

You will definetely not be able to implement this on all the switches at a same time so you can enable it on one switch and then start doing it on neighbor switches.

I will always recommed you when you raise a change request to implement this arrange some time for the same and also try to do it when there are minimal users.

Also recommend you to have a look at the link before implementing.

HTH

Ankur

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