Testing UDLD on copper interfaces

Hi all,

I have to verify the correct working of UDLD protocol on copper
interfaces.
In my lab two 6509 Catalysts are connected betweeen them with
4x10/100/1000 links, taken form a WS-X6148A-GE-TX port adapter. An
Etherchannel is used to combine these links into one logical channel.
Autonegotiation is already enabled on the involved interfaces and
Rapid Spanning Tree is configured.

I'm planning to enable aggressive UDLD on all these interfaces with
the "udld port aggressive" command; I'm looking a way to test if it
works. I think the most critical point would be how to simulate an
unidirectional link.

Any idea how to implement it? I''ve read on a forum about one possible
strategy: to put a non-Cisco L2 device between the two Catalysts and
unplug one side after the UDLD peers have been created.

Has anyone tested it successfully? Any other suggestion about
alternative ways to have an unidirectional link on copper interfaces?

Thanks
Alessandro

ango