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 –
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 |
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Download the comparison table here.
