Cisco’s vPC is a virtual port-channel which allows links physically connected to two different switches to appear as a single device to a downstream device as part of a single port-channel.
To learn more, I recommend reading NX-OS and Cisco Nexus Switching by Ron Fuller, David Jansen, and Matthew McPherson.
A vPC is configured on a Cisco Nexus switch and allows Layer 2 port-channels from a downstream device to span two separate switches.
vPC consists of two vPC peer switches connected by a vPC peer link. One switch is primary and the other is secondary. A vPC domain is formed by both Nexus switches. A Nexus can only be part of one vPC domain and only two switches can make up a vPC domain.
vPC peer link creates a single control plane which forwards BPDUs or LACP packets from the primary vPC switch to the secondary vPC switch. A vPC peer link is formed into a port-channel which can be a maximum of 16 ports but at a minimum it should be 2 ports. The peer link synchronizes MAC addresses and STP BPDUs.
In addition to the vPC peer link, there is a peer keepalive link which monitors the vPC peer switch. A keepalive link can be configured using the management interface or through an SVI. There is no data sent over this link. It’s sole purpose is for vPC keepalives.
A vPC port is a port assigned to a vPC channel group. Ports part of the vPC are split between the vPC peers.
Components of a vPC
- One primary switch and one secondary switch (vPC peers)
- Layer 3 link for peer-keepalives (resolves dual-active scenarios)
- Redundant port channel for a peer link between vPC peers.
- vPC port members forming a the virtual Port Channel.
Connect each switch together to create a vPC peer link. You need two 10 GbE interfaces.
Connect the management interfaces to each switch to form the vPC keepalive link. You lose out on using the management interface. In my scenario, these two Nexus switches will be racked together.
Enable the vPC feature.
conf t feature vpc
Configure the management interfaces. [Read more…] about Configuring Cisco Nexus vPC