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

Reply to
ango
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please note these blades are contended and not designed for trunk pipes.

a set of 6 or 8 ports shares 1 chip, and a single GigE internal connection.

if you must build an Etherchannel, make sure you combine ports from different "sets" or you are going to be limited to 1 Gbps anyway.

Reply to
Stephen

Maybe I miss something but it doesn't seem to me an effective way to test udld, as far as I know the most flexible way is to build a link with a couple of fiber media converters and plug/unplug each simplex fiber connector in order to close/open the link in any direction you like. Bye, Tosh.

Reply to
Tosh

Maybe you can block the UDLD packets with a mac access-list? UDLD uses the same destination mac as CDP.

If that does not work maybe a non-cisco intermediate switch that supported mac ACLs might work.

Remember too that GBE already protects against unidirectional links. I am not sure of the details but my understanding is that there is a physical layer protocol within GBE that ensures that neither port will up come unless both come up. Maybe worth reading the GBE standard which may be free from the IEEE.

Reply to
bod43

GigE includes negotiation which should sort out a local 1 way link issue. If you have just fibre between the 2 ciscos then that should be it.

It doesnt tend to work if there are intermediate devices mucking around with the bit stream since the negoiation is interface to adjacent interface.

I stumbled over this with a GigE over SDH module in a Marconi / Ericsson mux.

FWIW 802.1q link aggregation should also detect "break" style faults since the protocol involves exchanging hello packets on each link.

You may want to see what you get with a marginal fault where some proportion of the traffic gets trashed - these kinds of issue seem harder to find and troubleshoot, esp where you use load balancing across Ethernet links.

Reply to
Stephen

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