Configuring VPN FRR

If a CE is multi-homed to two PEs, you can configure VPN FRR to ensure that VPN services are switched to a standby link if the active link between PEs fails.

Usage Scenario

VPN FRR applies to services that are sensitive to packet loss and delay on VPN networks. As shown in Figure 1, CE1 is dual-homed to PE2 and PE3. VPN FRR is configured on PE1. If the link between PE1 and PE2 fails, VPN traffic needs to be rapidly switched to the link between PE1 and PE3.

Figure 1 VPN FRR

Prerequisites

Before configuring VPN FRR, complete the following tasks:

Configure a routing protocol on the routers to implement network connectivity.
Configure PE1 to ensure that two unequal-cost routes destined for the CE are available.
Set up a VPN network.

Background

You can enable VPN FRR in either the VPN instance IPv4 address family view or the BGP-VPN instance IPv4 address family view as needed. For example, if only BGP VPNv4 peers are configured on a device but no BGP-VPN instance is configured, you need to enable VPN FRR in the VPN instance IPv4 address family view.

Procedure

Enable VPN FRR in the VPN instance IPv4 address family view.
1. Run system-view
  The system view is displayed.
2. Run ip vpn-instance vpn-instance-name
  The VPN instance view is displayed.
3. Run ipv4-family
  The VPN instance IPv4 address family view is displayed.
4. Run vpn frr
  VPN FRR is enabled.
5. (Optional) Run quit
  Return to the VPN instance view.
6. (Optional) Run quit
  Return to the system view.
7. (Optional) Run bgp as-number
  The BGP view is displayed.
8. (Optional) Run ipv4-family vpn-instance vpn-instance-name
  The BGP-VPN instance IPv4 address family view is displayed.
9. (Optional) Run route-select delay delay-value
  A route selection delay is set. After the active path recovers, an appropriate delay ensures that traffic switches back to the active path after the intermediate devices refresh forwarding entries and the entries become stable, preventing packet loss during a traffic switchback.
  
  The delay-value value is an integer ranging from 0 to 3600, in seconds.
10. Run commit
  The configuration is committed.
Enable VPN FRR in the BGP-VPN instance IPv4 address family view.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  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
  VPN FRR is enabled.
5. (Optional) Run route-select delay delay-value
  A route selection delay is set. After the active path recovers, an appropriate delay ensures that traffic switches back to the active path after the intermediate devices refresh forwarding entries and the entries become stable, preventing packet loss during a traffic switchback.
  
  The delay-value value is an integer ranging from 0 to 3600, in seconds.
6. Run commit
  The configuration is committed.

Verifying the Configuration

After configuring VPN FRR, you can run the display ip routing-table vpn-instance vpn-instance-name [ ip-address ] verbose command to check the backup next hop (PE), backup tunnel, and backup label in the routing table of the VPN instance IPv4 address family.