Due to a more complex network topology (because of the desire to save money) I recently had to implement iBGP routing inside a VRF on a cluster of Cisco Nexus switches.
Configuring iBGP (Internal Border Gateway Protocol) within a VRF (Virtual Routing and Forwarding) instance on a Cisco Nexus switch involves several steps. Below is a step-by-step guide to help you set it up:
Step 1: Create the VRF
First, you need to create a VRF instance on your Nexus switch.
bash
Nexus(config)# vrf context VRF_NAME
Nexus(config-vrf)# rd 100:1
Nexus(config-vrf)# address-family ipv4 unicast
Nexus(config-vrf-af)# exit
Nexus(config-vrf)# address-family ipv6 unicast
Nexus(config-vrf-af)# exit
Nexus(config-vrf)# exit
Replace VRF_NAME with the name you want to assign to your VRF instance. The rd (route distinguisher) is a unique identifier for the VRF.
Step 2: Assign Interfaces to the VRF
Assign the relevant interfaces to the newly created VRF.
bash
Nexus(config)# interface Ethernet1/1
Nexus(config-if)# vrf member VRF_NAME
Nexus(config-if)# ip address x.x.x.x/xx
Nexus(config-if)# exit
Repeat this for each interface that should be part of the VRF.
Step 3: Configure the iBGP Peering
Configure the iBGP session within the VRF context.
bash
Nexus(config)# router bgp 65001
Nexus(config-router)# vrf VRF_NAME
Nexus(config-router-vrf)# address-family ipv4 unicast
Nexus(config-router-vrf-af)# neighbor PEER_IP remote-as 65001
Nexus(config-router-vrf-af)# neighbor PEER_IP update-source Loopback0
Nexus(config-router-vrf-af)# neighbor PEER_IP activate
Nexus(config-router-vrf-af)# exit
Nexus(config-router-vrf)# address-family ipv6 unicast
Nexus(config-router-vrf-af)# neighbor PEER_IP remote-as 65001
Nexus(config-router-vrf-af)# neighbor PEER_IP update-source Loopback0
Nexus(config-router-vrf-af)# neighbor PEER_IP activate
Nexus(config-router-vrf-af)# exit
Nexus(config-router-vrf)# exit
Nexus(config-router)# exit
65001is the AS number used for iBGP.PEER_IPis the IP address of the iBGP peer within the VRF.Loopback0is typically used as the update source, assuming your loopback interface is part of the VRF.
Step 4: Verify the Configuration
Verify the iBGP peering status and the VRF routes.
bash
Nexus# show bgp vrf VRF_NAME all summary
Nexus# show ip route vrf VRF_NAME
These commands will display the status of BGP neighbors and the routing table within the VRF.
Step 5: Troubleshooting
If you encounter issues, use the following commands to troubleshoot:
bash
Nexus# show bgp vrf VRF_NAME all neighbors
Nexus# show bgp vrf VRF_NAME all
Nexus# show ip bgp vpnv4 vrf VRF_NAME
Nexus# show ip bgp vpnv6 vrf VRF_NAME
These commands provide detailed information about BGP sessions and routes within the VRF context.
By following these steps, you should be able to successfully configure iBGP within a VRF on a Cisco Nexus switch.
More info about VRF.