On Mon, May 03, 2010 at 10:19:53AM +1000, Lincoln Dale wrote: > the keepalive link is not mandatory - but certainly best practice would be > for it to be operational as much as possible rather than having it on a > network that didn't have the same availability as your primary data path.
In our tests, unless there is a working vpc keepalive the vpc peer link will not be brought up when an N5K reloads. Cisco docs note that the keepalive is critical: http://www.cisco.com/en/US/docs/switches/datacenter/sw/4_1/nx-os/interfaces/configuration/guide/if_vPC.html#wp1385808 -------------------- "The Cisco NX-OS software uses the peer-keepalive link between the vPC peers to transmit periodic, configurable keepalive messages. You must have Layer 3 connectivity between the peer devices to transmit these messages; the system cannot bring up the vPC peer link unless the peer-keepalive link is already up and running." -------------------- We have found that if the vpc keepalive connectivity (call it "vpk" for convenience) does not come up first, then even though the vpc peer links are up the vpc port-channel ints on that switch will be down and associated physical ints will be protocol down ("suspended"). Here's what you see in the log after reloading with a failing vpk: -------------------- N5K-B %VPC-3-VPC_PEER_LINK_BRINGUP_FAILED: vPC peer-link bringup failed (peer-keepalive not operational, peer never alive) -------------------- If the vpk path is working at switch boot time but then fails later, the vpc portchannels across the two switches will keep working until a switch is reloaded, at which point the reloaded switch will fail to find a vpc role and all vpc portchannels on the switch will stop working. "show vpc brief" after a switch is reloaded with a non-functional vpk path for that vpc domain: -------------------- vPC domain id : 100 Peer status : peer link is down (peer-keepalive not operational, peer never alive) vPC keep-alive status : Suspended (Destination IP not reachable) Configuration consistency status: failed Configuration consistency reason: Consistency Check Not Performed vPC role : none established -------------------- -Charles Charles E. Spurgeon / UTnet UT Austin ITS / Networking c.spurg...@its.utexas.edu / 512.475.9265 _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/