Simulating UniDirectional Link Failure

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Jun 17th, 2008
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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.


thanks

Dave

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Nagendra Kumar ... Tue, 06/17/2008 - 01:51
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  • 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.


HTH,

Nagendra

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


ta

Dave

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

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