A single end device can use a port channel across two upstream switches. Cisco Nexus switches with vPC appear to downstream devices as if they are a single device. The other device can be a switch, a server, or any other networking device that supports the IEEE 802.3ad port channel.

Cisco NX-OS software virtual port channel (vPC) and Cisco Catalyst Virtual Switching System (VSS) are similar technologies. Per Cisco EtherChannel technology, the term multichassis EtherChannel (MCEC) refers to either technology interchangeably.

The key difference between a vPC and a VSS is that the VSS creates a single logical switch. This results in a single control plane for both management and configuration purposes. With vPCs, each Cisco Nexus switch (vPC) is managed and configured independently. They remain two separate physical andeach of them is a logical switch. Only for the communication of the vPC they present themselves in front of the third device connected to them using the vPC as one logical switch. In this way, the network devices communicating with the switches, which form the vPC pair, can see them either as two separate network switch, if they do not use the vPC port-channel, or they will behave as a single logical device for the vPC port-channel communication. And this is a major difference with the VSS. A vPC allows the creation of Layer 2 port channels that span two switches.

vPCs eliminate STP block ports. Downstream devices can use all available uplink bandwidth and provide fast convergence upon link/device failure. vPCs consist of two vPC peer switches connected by a peer link. One is the primary, and the other is the secondary. The system formed by the switches is referred to as a vPC domain. Cisco Nexus switches form different topologies,