Configuring IP+VPNv4 Hybrid FRR

Context

Hybrid FRR is used in CE dual-homing scenarios. If the next hop of the route from a PE to a CE is unreachable, hybrid FRR can quickly switch the route to the backup link. The traffic is then forwarded to the backup PE over a VPN tunnel and finally sent to the destination through IP forwarding on the private network.

IP+VPNv4 hybrid FRR can be configured in CE dual-homing scenarios to quickly switch traffic to the backup PE when the next hop of the route from a PE to a CE is unreachable.

As shown in Figure 1, IP+VPNv4 hybrid FRR is configured on PE2. Link A between PE2 and CE3 is the primary link, and Link B along PE2, PE3, and CE3 is the backup link. When PE2 detects that Link A is unreachable, it immediately switches VPN traffic to Link B and then performs other operations to trigger VPN route convergence. This minimizes impact of the link failure on VPN services.

Figure 1 Networking for IP+VPNv4 hybrid FRR

The device supports two ways to implement IP+VPNv4 hybrid FRR, which are applicable to different networking environments and configured differently:

IP FRR: used when a routing protocol other than BGP is running between PE and CE devices.
BGP auto FRR: used when only BGP is running between PE and CE devices.

Perform the following configuration on PE devices to which a CE is dual homed.

Procedure

Configure IP FRR.
1. Run system-view
  
  The system view is displayed.
2. Run route-policy route-policy-name { permit | deny } node node
  
  A route-policy node is created, and the route-policy view is displayed.
3. Run apply backup-nexthop ipv4-address
  
  A backup next hop is specified.
  
  To ensure that the route can be iterated to the backup tunnel, set ipv4-address to the loopback interface address of the peer PE.
4. Run quit
  
  Return to the system view.
5. Run ip vpn-instance vpn-instance-name
  
  The VPN instance view is displayed.
6. Run ipv4-family
  
  The VPN instance IPv4 address family view is displayed.
7. Run ip frr route-policy route-policy-name
  
  IP FRR is enabled.
Configure BGP auto FRR.
1. Run system-view
  
  The system view is displayed.
2. Run bgp { as-number-plain | as-number-dot }
  
  The BGP view is displayed.
3. Run ipv4-family vpn-instance vpn-instance-name
  
  The BGP-VPN instance IPv4 address family view is displayed.
4. Run auto-frr
  
  BGP auto FRR is enabled for the BGP-VPN instance IPv4 address family.

Verifying the Configuration

Run the display ip routing-table vpn-instance vpn-instance-name [ ip-address ] verbose command to check the backup next hop, backup tunnel, and backup label for a VPN route.