Introduction to VPC and VSS

Both VPC and VSS are used basically to support multi-chassis ether-channel that means we can create a port-channel whose one end is device A, however, another end is physically connected to 2 different physical switches which logically appears to be one switch.

The Differentiation between both the feature set is tabled below –

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SNo	VPC	VSS
1	Feature specific to Nexus	Feature specific to catalyst 6500,4500 Series
2	Separate control plane for both switches.	2 Switches merge to form 1 logical Switch with a single control plane.
3	Separate IP for each switch management and configuration.	Single IP for management and configuration of 1 Logical Unit (2 Physical Chassis)
4	HSRP is required.	First Hop Redundancy Protocol like HSRP not required.
5	Separate instance of STP, FHRP, IGP, BGP etc. will be required on each physical Switch of VPC.	Same instance of STP, FHRP, IGP, BGP etc. will be used on each physical Switch of VSS.
6	Both the switches are active and work individually. Only from VPC perspective are they elected primary and secondary.	Switches are always primary and secondary from all aspects.
7	Supports L2 Port Channels	Supports L3 Port Channels
8	Supports LACP	Supports PAGP and LACP
9	Control messages are carried by CFS over Peer Link and a Peer keep alive link is used to check heartbeats and detect dual-active condition	Control messages and Data frames flow between active and standby via VSL