True or False; you should disable Spanning-Tree on the Arista MLAG peer link VLAN?

The VLAN designated for the MLAG peer link is a special-purpose, point-to-point control plane link used exclusively for communication between the two MLAG peer switches. This communication includes synchronizing MAC and ARP tables and exchanging MLAG control protocol messages. The MLAG protocol itself inherently manages the Layer 2 topology to prevent loops from the perspective of downstream devices. Enabling Spanning Tree Protocol (STP) on this dedicated VLAN is not only unnecessary but can be disruptive. If STP were to calculate a loop and block the peer link port, it would sever the control plane connection, leading to a "split-brain" scenario where both peers operate independently, causing network instability and traffic disruption. Therefore, the standard and required best practice is to disable STP on the MLAG peer link VLAN.

The option "False" is incorrect because enabling Spanning Tree on the peer link VLAN directly conflicts with the operational requirements of MLAG. The MLAG control plane relies on a stable, uninterrupted connection over the peer link. STP, by design, could block this link, which would break the MLAG domain and negate the benefits of high availability and redundancy that MLAG is designed to provide.

1. Arista Networks, EOS 4.31.1F Configuration Guide: In the "MLAG" chapter, under the section "Configuring the Peer Link," the guide explicitly states the configuration requirement. It notes, "On the VLAN dedicated to the peer link, spanning tree must be disabled." This is presented as a mandatory step in the configuration process.

Reference: Arista EOS 4.31.1F Configuration Guide, Chapter: "MLAG", Section: "Configuring the Peer Link".

2. Arista Networks, "MLAG Best Practices" Design Guide: This document outlines the recommended design and configuration for a stable MLAG deployment. In the section covering the peer link, it reinforces this rule.

Reference: Arista Design Guides, "MLAG Best Practices", Section: "Peer Link", Subsection: "Configuration". The guide states: "Create a dedicated VLAN for the peer link. This VLAN should not be trunked anywhere else in the network. Disable spanning tree on this VLAN."

3. Arista Networks, "MLAG - Basic Configuration" Article: In this foundational configuration example on the Arista Community Central portal, the steps clearly demonstrate the requirement.

Reference: Arista Community Central, "MLAG - Basic Configuration" (Arista Validated Design), Configuration Example for Peer A and Peer B. Step 3 of the peer link configuration shows the command no spanning-tree vlan being applied to the peer link VLAN.