Cisco vPC Setup and Caveats

This was my first time setting up Cisco vPC between two Nexus 3K switches and I wanted to document some findings the deviated from their documentation a bit.

NXOS: version 7.0(3)I7(6) was used in this environment.

Here is the topology:

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3000/sw/layer2/503_U2_1/b_Cisco_n3k_layer2_config_guide_503_U2_1/b_Cisco_n3k_layer2_config_gd_503_U2_1_chapter_01000.html#concept_692519898AC94234AAE63D401054816A

The above link does a great job explaining the requirements for vPC and what is involved including using LACP. The only real caveat is when creating the Etherchannel for the vPC peer or downstream port-channels I had to follow this order specifically or it would say that the ports were not compatible when I tried to add them to a port-channel using the channel group command. Cisco’s documentation for Etherchannel suggests adding the port-channel interface first then adding the individual ports to the port-channel.

First add the ports to the port-channel then create the port-channel interface:

conf t
int e 1/49
switchport mode trunk
channel-group 100 mode active

int e 1/50
switchport mode trunk
channel-group 100 mode active

exit

int port-channel 100
switchport mode trunk

Here is a full snippet relevant to the vPC config:

Nexus A:

vrf context management
   ip route 0.0.0.0/0 10.10.10.1
 
 vpc domain 1
   peer-keepalive destination 10.10.10.20 source 10.10.10.10
   auto-recovery

 interface port-channel1
   switchport mode trunk
   vpc 1

 interface port-channel100
   switchport mode trunk
   spanning-tree port type network
   vpc peer-link

 interface Ethernet1/48
   switchport mode trunk
   channel-group 1 mode active

 interface Ethernet1/49
   switchport mode trunk
   channel-group 100 mode active

 interface Ethernet1/50
   switchport mode trunk
   channel-group 100 mode active

 interface mgmt0
   vrf member management
   ip address 10.10.10.10/24
 line console

Nexus B:

vrf context management
   ip route 0.0.0.0/0 10.10.10.1
 
 vpc domain 1
   peer-keepalive destination 10.10.10.10 source 10.10.10.20
   auto-recovery

 interface port-channel1
   switchport mode trunk
   vpc 1

 interface port-channel100
   switchport mode trunk
   spanning-tree port type network
   vpc peer-link

 interface Ethernet1/48
   switchport mode trunk
   channel-group 1 mode active

 interface Ethernet1/49
   switchport mode trunk
   channel-group 100 mode active

 interface Ethernet1/50
   switchport mode trunk
   channel-group 100 mode active

 interface mgmt0
   vrf member management
   ip address 10.10.10.20/24
 line console

Nexus C:

vrf context management
   ip route 0.0.0.0/0 10.10.10.1

 interface port-channel1
   switchport mode trunk

 interface Ethernet1/49
   switchport mode trunk
   channel-group 1 mode active

 interface Ethernet1/50
   switchport mode trunk
   channel-group 1 mode active

 interface mgmt0
   vrf member management
   ip address 10.10.10.30/24
 line console