FEX testing

Now I've got the FEXs up and running, there are various things I wanted to test and confirm so I can better understand how they work and, more importantly, how to find things that have gone wrong.

Port-VLAN inconsistency across upstream switches

When a FEX is dual-homed to a pair of upstream switches, each of those switches will have a configuration for the ports on the FEX.  By default, these are NOT automatically kept in step (although something called configuration synchronization can do this, which I'll go over later as I've been looking at that too).

If the ports are configured identically on both switches, everything is hunky dory:

n5k-top(config)# int e101/1/3
n5k-top(config-if)# switchport access vlan 808

n5k-bottom(config)# int e101/1/3

n5k-bottom(config-if)# switchport access vlan 808

n5k-top# show int e101/1/3 status

--------------------------------------------------------------------------------

Port          Name               Status    Vlan      Duplex  Speed   Type

--------------------------------------------------------------------------------

Eth101/1/3    --                 connected 808       full    a-1000  --

However, if one of the switches has a different configuration, the port becomes inactive:

n5k-bottom(config)# int e101/1/3

n5k-bottom(config-if)# switchport access vlan 812

n5k-bottom# show int e101/1/3 status

--------------------------------------------------------------------------------

Port          Name               Status    Vlan      Duplex  Speed   Type

--------------------------------------------------------------------------------

Eth101/1/3    --                 inactive  812       full    auto    --

This error can be explained with the "show int ... status err-vlans" command:

n5k-bottom# show int e101/1/3 status err-vlans

--------------------------------------------------------------------------------

Port         Name               Err-Vlans                     Status

--------------------------------------------------------------------------------

Eth101/1/3   --                 812                           Vlan is not

                                                              configured on

                                                              remote vPC

                                                              interface

It doesn't show up in the verbose show int command output, which seems a bit of an omission.

Once corrected, the port immediately springs back into life.