vPC in Suspend mode after adding a VLAN

[Jay74]

Hi Guys,

i hope i got a solution for the described issue.

We have 2 Nexus 9K in a vPC Domain and 2 Cisco Catalys 2960 in a Cluster configuration.
Between Nexus and Catalyst we have configured a Port-Channel and it works fine.
Some weeks ago i add an new vlan to this port-channel and it works fine.
Two weeks ago i add an new vlan to this port-channel and it runs into suspend mode on nexus side.

Therefore i want to no is this an error or maybe an feature or it the wrong order i add it.
The only difference between both cases is in case one that i begin configuring at nexus side.
At the second case i begin configuring on catalyst side.

I perform the following steps in this order:
1) create vlan
2) add vlan to the physical interfaces (because our supplier advice us to add vlans for port channels also to the physical interfaces)
3) add vlan to the port-channel

In the second case i run into an error after i add the vlan to the physical interfaces at the catalyst.
The (v) port-channel runs into suspend mode. The new vlan was added at this time a the nexus.
In my opinion this shouldnt happen and the nexus should drop those packets in case that the new vlan is unknown.

Has anyone else a issue like that or could explain what happen ?

Thanks for your help.
Jay

[Sergiu.Daniluk]

Hi @Jay74 

Did the vPC-enabled port-channel went into suspended mode?

What was the reason? what did you saw in show vpc / show int po X. Can you share show logging log and tell what was the date/time the problem appeared?

Cheers,

Sergiu

[Jay74]

Hi Sergiu,

thanks for the fast reply.

Regarding your questions:

1) no the Portchannel went into noOperMem mode only the physical interfaces went into suspended mode like this:

show int stat:

Eth1/45 Portchannel3 suspended trunk full 10G SFP-H10GB-CU5M
Eth1/46 Portchannel3 suspended trunk full 10G SFP-H10GB-CU5M
Po3 Interface-1/45-1/46 noOperMem trunk full 10G --

2) The reason was an:

interface TenGigabitEthernet XXX

switchport trunk allowed vlan add XXX

at the catalyst switches, after this the nexus interfaces went into suspended mode. At this time the new vlan was configured at the port-channel and also not at the nexus switches.

3) Unfortunaly i have no show vpc or sh int po x. But i add the logs from the nexus switch. We rebooted them and therefore we have no logs before reboot. The reboot finished at 11:47, i think the entrys before are maybe usefull. 

Thx

Jay

[Jay74]

Additional information:

Some weeks before this issue, i made the same steps and add a vlan.

The difference between both changes was that i first add the nee vlan at the nexus switches.

Then it works.

Maybe the nexus must know the new vlan before adding it to the portchannel member.

[Sergiu.Daniluk]

The order of which switch is configured with the vlan should not matter. Definitely more logs are required for analysis.

Regards,

Sergiu