lacp key

[jallen202020]

So, this may be a dumb question, but one that has always bugged me.  When creating an LACP trunk in an ERS switch, you need the lacp key XX command.  I've always just entered it to get things working, and not thought much of it.  But why do we need it?  What does it do?  Why don't other switch brands require some identifier like that to create lacp trunks on their end?  What would happen if i didn't enter it?

If there's some documentation out there anyone can point me to, or an explanation anyone can give, it would be much appreciated.

Thanks!

[jallen202020]

So I found this:

"Each LAG on a system will have a unique 16 bit LACP key, the purpose of which is to differentiate one LAG from another within the protocol. This number is locally significant and may or may not match between peers.The main purpose of the LACP key is to allow a system to detect cabling faults - if different LACP keys are received on members of the same LAG then we are connected to two different LAGs at the far end and, obviously, aggregating those together would be a bad idea."

This makes sense and is along the lines of what I figured, but why do we have to statically set it on an ers switch?  If we don't issue that command, will the switch just automatically pick a key?

[Paul L]

all switches use LCAP with a key. 

Here is a good guide that explains it. 

https://downloads.avaya.com/css/P8/documents/100123693