LACP passive

[phil96564]

Hi all

I have an SQL server that is due to move to a new pair of Nexus 9000 leaf switches, with a VPC configured between them. The ports on the new switches are configured as LACP active, just like the other SQL servers, and when this move was first attempted one of the switch ports went into suspended mode caused, according to the switch's log, by no LACP packets being received from the server.  One of my colleagues has suggested changing the ports to LACP passive which I understand means the ports form a trunk only if the other end requests it. His suggestion is on the basis that the switch then doesn't care whether the server sends LACP packets or not.

My question is then if I configure the ports as LACP passive and the server doesn't send LACP packets will there be connectivity at all? I know it won't form a trunk because the switch ports are waiting for LACP packets so will the ports act like access ports? 

Thanks in advance,

Phil.

[MHM Cisco World]

can you more elaborate  

MHM

[MHM Cisco World]

I run lab abd it work in both cases 
LACP in NSK Active - SW (server in your case) Use Passive
LACP in NSK ON - SW (server in your case) Use ON

for me I dont link use ON mode if the both device have capability to use LACP, so the Q are you sure the SQL server send LACP or run LACP in PO?

MHM

[David Ruess]

Hello,

I'd have to do some testing but I don't believe that is quite correct. Also the trunking status of the ports has nothing to do with LACP configuration. That's another set of commands entirely. I assume you mean port-channel or bundling of the ports. For instances like this when the remote side doesnt send any kind of port-channeling configuration most people use the command: channel-group <#> mode on. The ON keyword bundles the ports in the channel regardless of what it hears from the other side. This can be dangerous as there is no checks to see if your configuration causes a loop. Its understood you know your links/topology to prevent this.

Edit: After doing a small lab for testing the "Passive" interface side did NOT come up when nothing was configured on the other side. It also did not come up when I configured channel-group mode ON on the other side just to bundle the ports and see if the passive side would come up. So passive needs to hear the peers active messages to function. 

Hope that help

-David