Simulating UniDirectional Link Failure

Unanswered Question
Jun 17th, 2008
User Badges:

Hi folks,

I may be losing the plot but can I simulate unidrectional link failures using fibre to help my CCNP studies? I thought it would be a simple matter of pulling out just the rx on one of my switches but that brings the int down. Is this how it's supposed to work?

I want to do this to look further into udld.



  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Nagendra Kumar ... Tue, 06/17/2008 - 01:51
User Badges:
  • Cisco Employee,

You can use PACL to simulate unidirectional link failure. UDLD uses 0100.0ccc.cccc as destination MAC address.

So configure a PACL denying this mac address and apply the same to the interface on which you need to simulate the link failure.



d.hodgson Tue, 06/17/2008 - 05:56
User Badges:

Thanks Nagendra,

I'll look up PACL.

Now what about the fibre failure I simulated, is expecting that to be a unidirectional link failure a wrong assumption?



h.parsons Tue, 06/17/2008 - 12:32
User Badges:

It is my understanding that your assumption is right. One thing to note is that both switches will have to establish a bidirectional state once before UDLD will shutdown an interface. Try connecting them and do a "show udld neighbors"


This Discussion