Users Guide

Table Of Contents
Role of VLT backup link in the prevention of loops during VLTi failure
When the VLTi is down, STP may fail to detect any loops in the system, which creates a data loop in an L2 network.
In the following figure, STP is running in all three switches:
In the steady state, VLT Peer 1 is elected as the root bridge. When the VLTi is down, both the VLT nodes become primary. In this state,
VLT Peer 2 sends STP BPDU to TOR assuming that TOR sends BPDU to VLT Peer 1. Due to this, VLT Peer 2 does not receive BPDU on
the VLT port, but receives TOR BPDU from the orphan port. The STP in VLT Peer 2 assumes that there is no loop in the system and
opens up both the VLT and the orphan ports. Opening up both the VLT and orphan ports creates a data loop in the system which brings
down the system.
Virtual Link Trunking
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