[c-nsp] LACP and UDLD ?

[William Cooper]

802.3ad / LACP will detect the forwarding failure and stop forwarding
over the affected links.

Regarding the speed of detection, there are two modes LACP can run in,
slow (30 seconds) and fast (1 second).
Both ends of the link need must run the same timers.

The other advantage is that it is an IEEE spec vs proprietary implementation.

Googling 802.3ad / LACP will result in a ton of reference material.

HTH,

-Tony

On Fri, Nov 12, 2010 at 12:02 PM, Keegan Holley
<keegan.holley at sungard.com> wrote:
> On Fri, Nov 12, 2010 at 10:37 AM, Jeff Fitzwater <jfitz at princeton.edu>wrote:
>
> I'm not sure they have the same function.  LACP will just drop the link from
> the bundle.  After that you may have a bridging loop anyway, just on a
> non-bundled port.  I can't remember exactly how LACP negotiation works, but
> things get worse if only one side removes the UD link from the bundle.
>  Also, I think UDLD reacts much faster than LACP.
>
> If I am running LACP between two Cisco switches, will it detect a
>> unidirectional link (bad fiber one direction), or should I run UDLD also?
>>
>> I would think LACP would detect a unidirectional link just because of the
>> nature of the proto, and take down that channel port.
>>
>> We may have to channel to a non cisco box, which does not support UDLD, so
>> if LACP can deal with a unidirectional link I won't have to worry about
>> UDLD.
>>
>> Thanks,
>>
>>
>>
>> Jeff Fitzwater
>> OIT Network Systems
>> Princeton University
>>
>>
>>
>>
>>
>>
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