vPC Peer Switch Feature Benefits

Explanation.

The vPC (Virtual Port Channel) peer switch feature is a Cisco technology that allows two Nexus switches to act as a single logical switch to a downstream device. The vPC peer switch feature provides a number of benefits, including:

A. After the peer link comes up, it performs an ARP bulk sync over CFSoE to the peer switch: This feature is known as ARP synchronization. After the peer link comes up, the vPC peer switches synchronize their ARP tables over the Control and Forwarding Separation over Ethernet (CFSoE) protocol, ensuring that both switches have identical ARP tables. This helps avoid ARP caching issues and reduces the time it takes to reroute traffic in case of a failure.

B. It improves convergence for Layer 3 flows: vPC peer switches can be configured to use Layer 3 routing protocols such as OSPF or BGP. When a failure occurs, the vPC peer switch feature allows for faster convergence of Layer 3 routing, reducing the time it takes to reroute traffic and improving overall network availability.

C. It allows a pair of vPC peer devices to appear as a single STP root in the Layer 2: vPC peer switches can be configured to act as a single Spanning Tree Protocol (STP) root in the Layer 2 network. This simplifies STP configuration and eliminates the need to manually configure STP priorities.

D. It simplifies STP configuration by configuring both vPC with the same STP priority: By default, vPC peer switches have different STP priorities. To simplify STP configuration, both switches can be configured with the same STP priority, ensuring that the primary switch is always the STP root.

E. It eliminates the recommendation to pin the STP root to the vPC primary switch: In traditional STP configurations, it is recommended to pin the STP root to a single switch to avoid unnecessary traffic across the vPC peer link. However, with the vPC peer switch feature, the primary switch can be elected as the STP root, simplifying STP configuration and reducing the risk of network loops.

In summary, the vPC peer switch feature provides a number of benefits including improved convergence, simplified STP configuration, and the ability to appear as a single logical switch in the Layer 2 network.