Nexus – Virtual Port Channel (vPC)

Port Channel:

Multiple ports bundled together such that they appear as a single port. Port Channel runs between 2 devices. Port Channel utilizes LACP (Standard) or PAgP (Cisco Proprietary).

Virtual Port Channel:

Multiple ports bundled together such that they appear as a single port. In the case of vPC, the links are connected to two different Cisco Nexus devices and appear as a single Port Channel to a 3rd device.

A simple vPC setup is shown here:

vpc_2

This diagram provides an introduction to vPC terminology:

vPC – Port Channel between vPC peer and the downstream device.

vPC Domain – Pair of vPC Switches.

vPC Peer – A vPC switch in a common vPC Domain.

vPC Member Port – One of a set of ports to form vPC.

vPC Peer Link – Link used to synchronize state between vPC peer devices, must be 10G

vPC Peer Keepalive Link – Keepalive link between vPC peer devices.

vPC VLAN – Any of the VLANs carried over the vPC Peer Link.

Orphan Device – A device on a vPC VLAN but only connected to only one vPC Peer and not both.

Orphan Port – An orphan port is a interface that connects to an Orphan Device.

Reference: 

Cisco Whitepaper on vPC

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