Users Guide

Configure BFD in VLT Domain
Dell EMC Networking OS supports Bidirectional Forwarding Detection (BFD) to detect communication failures on an interface
that is a part of a VLT link aggregation group (LAG).
In VLT domain, BFD provides high availability path when there are communication failures in any one of the VLT LAG links. The
VLT nodes and top of rack (ToR) use the VLT LAG links to carry the BFD packets. When any one of the VLT LAG links
connected to the ToR is down, the BFD packets reach the VLT primary or secondary using the VLTi (ICL) link.
When VLT peer-routing is enabled, BFD sessions are not established if BFD packets reach the wrong VLT node due to LAG
hashing in TOR. The wrong VLT node must have ARP or IPv6 neighbor discovery entries for VLT peer node's IPv4 or IPv6
address in the forwarding table, to forward the BFD packet to the VLT peer. Since ARP or IPv6 neighbor discovery entries are
bound to expire, it is recommended to add static ARP or IPv6 neighbor discovery entries for the VLT peer node's IPv4 or IPv6
address, to forward the BFD packets to the correct VLT node.
Sample BFD configuration in VLT domain
The following shows the sample configuration of BFD implementation in VLT environment:
ToR
1. Enable BFD globally.
TOR(conf)# bfd enable
2. Configure a VLT peer LAG.
TOR(conf)#interface twentyFiveGigE 1/1
TOR(conf-if-tf-1/1)#no ip address
TOR(conf-if-tf-1/1)#port-channel-protocol lacp
TOR(conf-if-tf-1/1)#port-channel 10 mode active
TOR(conf-if-tf-1/1)#no shutdown
TOR(conf)#interface twentyFiveGigE 1/2
TOR(conf-if-tf-1/2)#no ip address
TOR(conf-if-tf-1/2)#port-channel-protocol lacp
TOR(conf-if-tf-1/2)#port-channel 10 mode active
TOR(conf-if-tf-1/2)#no shutdown
Virtual Link Trunking (VLT)
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