Exploring vPCs and their verification

By | August 5, 2014

Virtual Port Channels (vPCs) allow you to ether channel or bundle multiple ports to the different devices.  Since the 7k/5k devices are looked at as one big virtual device, you can now use ether channel or load balancing and redundancy between multiple Nexus switches.

vPC Peers are the bundled devices that act as one single device for anything connected downstream.
vPC Peer Link binds the control plane and allows communications between the bundled Nexus switches.  This syncs your MAC tables and IGMP entries for snooping purposes.  This must be a 10 GB port and it is recommended that at least 2 are configured.
Orphan ports are ports that are not participating in the vPC infrastructure.
Member ports are ports that are part of the vPC configuration
CFS stands or Cisco Fabric Services that allows this technology work.
Peer Keepalive links are used on out of band networks that provide Layer 3 communications as a secondary test to ensure the remote peer is operating properly.  This isn’t used for data or sync messages, it is solely used for health checks.

On the device connected to the vPC peers, it will be configured as a normal EtherChannel or LACP link.  However on the upstream devices the vPC gets configured.  A Domain ID needs to be assigned to your vPC as well.  It is important to note that this is a Layer 2 port channel.  vPC’s are great for going from 7k’s to 5k’s then 5k’s to 2k’s down to the server.

show vpc brief – shows the vPC configuration and status.  This also shows the vPC domain id and lets you know if you are on the primary or standby device.

show vpc peer-keepalive – This shows the keep alive status for the layer 3 keep alive checks.

show vpc role – Shows the role and MAC info as well as priority values.  The lower the value, the higher the priority.

show vpc consistency-parameters – Shows important local values for the vPC setup include link/interface information and compares it to your peer.