vPC is a virtualization technology that presents paired or two Nexus devices as a unique Layer 2 logical node to the access layer devices or endpoints. vPC belongs to Multi chassis EtherChannel [MCEC] family of technology. A virtual port channel (vPC) allows links that are physically connected to two different Cisco Nexus 7000/5000/9000 Series devices to appear as a single port channel to a third device. The third device can be a switch, server, firewall, load balancer or any other networking device that supports link aggregation technology.
VPC or Virtual Port Channel is a Cisco proprietary feature available on the Nexus platform. Two switches of the same model can be combined into a VPC pair, which can establish a single EtherChannel, also known as a link aggregate or a port channel, across both switches to a third switch or server. This peering device doesn’t know that it is connected to two different switches, and it just needs to support link aggregation either statically or using Link Aggregation Control Protocol (LACP).
MultiChassis EtherChannel (MCEC) or MultiChassis Link Aggregation (MLAG) terms refer to the technique of bundling links across more than 1 device. VPC is Cisco’s implementation of MCEC/MLAG on the Nexus line of switches. Similarly, Cisco Catalyst switches support Virtual Switching System (VSS) or StackWise-based MLAGs.