VPC - [Part 5] - PEER LINK

• VPC Peer Link is also known as the Multi-Chassis Ether Channel (MCE) Trunk. 

• It is used to synchronize states between the VPC peer devices. 

• It is responsible to control the traffic between two VPC switches and also multicast, broadcast data traffic. 

• In the situation of link failure, it carries uni-cast traffic also. 

• Peer links required at least two 10 Gigabit Ethernet interfaces.

• VPC Peer Link forms a virtual Control Plane across the two switches, so that's why both switches will appear as one.

• Sharing Mac Address - Peer switches use the peer-link to share the MAC addresses. If one switch will insert a MAC address into its forwarding table, then it will send the MAC to its peer and peer will insert this MAC into its own forwarding table. So it make the convergence fast. If one switch (Switch-A) fails, then other switch (Switch-B) can continue to forward traffic without disruption because second switch (Switch-B) has already learned all the available MAC addresses via its peer.

• The peer-link is responsible to carry all the VLANs that will appear on VPC member ports. VPC Peer Keep-alive link should be up and operational before you will configure VPC Peer-Link.

• You can check the below sample - How can we configure VPC Peer Link.

NexusA - 

NexusA(config)# interface eth 1/10-11

NexusA(config-if-range)# channel-group 999 mode active

NexusA(config-if-range)# no shutdown

NexusA(config-if-range)# interface port-channel 999

NexusA(config-if)# no shutdown

NexusA(config-if)# switchport mode trunk

NexusA(config-if)# vpc peer-link

NexusB - 

NexusB(config)# interface eth 1/10-11

NexusB(config-if-range)# channel-group 999 mode active

NexusB(config-if-range)# no shutdown

NexusB(config-if-range)# interface port-channel 999

NexusB(config-if)# no shutdown

NexusB(config-if)# switchport mode trunk

NexusB(config-if)# vpc peer-link

• Yo can verify VPC Peer Link via command - show vpc brief

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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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