VPC - [Part 6] - PEER KEEPALIVE LINK

• VPC Peer keep-alive link sends periodic keep-alive messages between VPC peer devices. It can be a management interface or Switched Virtual Interface (SVI). It sends the messages between two VPC peer device, VPC peer sends the keep-alive message to other peer to inform, originating switch is operating and running VPC.

• It is a layer-3 link, it will be in a separate VRF to provide separate traffic from other traffics .

• We can deploy this link in two different ways. 

1. Separate layer-3 network - It may be the a distribution, core or management networks.
2. Point-to-Point routed connected between the two switches - Using management interface

• This link will carries only small packets, so it will not consume a lot of bandwidth. 

• And there is no any requirement of a group of links in a port-channel. So this means, keep-alive can be a single link between normal ports over a custom VRF or it can be a single point to point link between management interfaces

• You can check the below example - how can we configure keep-alive link using a dedicated port - Add a dedicated layer-3 port in VRF and assign an IP address.

Method 1 -  Separate layer-3 network

Configure VRF to provide separate keep-alive link - 

NexusA-
NexusA(config)# vrf context VPC_KEEPALIVE
NexusA(config-vrf)# exit

NexusB-
NexusB(config)# vrf context VPC_KEEPALIVE
NexusB(config-vrf)# exit

Configure Keep Alive port

NexusA-
NexusA(config)# interface eth 1/30
NexusA(config-if)# no switchport
NexusA(config-if)# vrf member VPC_KEEPALIVE
NexusA(config-if)# ip address 172.24.2.6/30
NexusA(config-if)# no shutdown

NexusB-
NexusB(config)# interface eth 1/30
NexusB(config-if)# no switchport
NexusB(config-if)# vrf member VPC_KEEPALIVE
NexusB(config-if)# ip address 172.24.2.5/30
NexusB(config-if)# no shutdown

Method 2 - Point-to-Point routed connected between the two switches

Use the Management interface

NexusA - 
NexusA(config)# interface mgmt 0
NexusA(config-if)# ip address 172.24.2.6/30
NexusA(config-if)# vrf context VPC_KEEPALIVE
NexusA(config-if)# no shutdown

NexusB - 
NexusB(config)# interface mgmt 0
NexusB(config-if)# ip address 172.24.2.5/30
NexusB(config-if)# vrf context VPC_KEEPALIVE
NexusB(config-if)# no shutdown

• You can verify this via command - ping [Destination IP address] vrf [VRF-name].

• You can chesk the VPC peer keep-alive detail via command - show vpc peer-keepalive.

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Anubhav Upadhyay

Hello and welcome to networktopic Blog. My name is Anubhav. I am a Senior Network Egineer. I have created this blog specially to serve interview questions and answer on Network Routing and Switching, I will try my best to serve correct and updated networking knowledge for you as per my corporate experience.

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