Configuring IP FRR on the Public Network

Usage Scenario

On a traditional IP network, when a lower-layer failure occurs on the forwarding link of a device, the physical interface of the device becomes Down. After the device detects the failure, it instructs the upper-layer routing system to recalculate routes and update routing information. It often takes the routing system several seconds to reselect an available route.

Second-level convergence is intolerable to the services that are quite sensitive to delay and packet loss because it may lead to service interruptions. For example, Voice over Internet Protocol (VoIP) services are only tolerant of millisecond-level interruptions. IP FRR ensures that the forwarding system rapidly responds to link failures and uses backup routes to forward data, minimizing service traffic interruptions.

Only the S5720-EI, S5720-HI, S5720I-SI, S5720S-SI, S5720-SI, S5735-S, S5735S-S, S5735-S-I, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S support this function.

Pre-configuration Tasks

Before configuring IP FRR on the public network, complete the following tasks:

Configure static routes or an IGP to ensure that there are reachable routes between devices.
Configure different costs for routes to generate two non-equal-cost routes.

Configuration Procedure

Configure a route-policy and then enable IP FRR on the public network for the route-policy.

Procedure

Configure a route-policy.
1. Run system-view
  The system view is displayed.
2. Run route-policy route-policy-name { permit | deny } node node
  A route-policy is created and the route-policy view is displayed.
3. (Optional) Run if-match
  Matching conditions are configured to filter the routes to be backed up.
  
  Select the if-match command according to (Optional) Configuring an if-match Clause.
  
  If no matching condition is configured, backup outbound interfaces and backup next hops will be specified for all routes of the device. This, however, causes backup information to be specified for some routes that do not need to be backed up. To correctly configure backup between routes, you are advised to configure matching conditions.
4. Run apply backup-interface interface-type interface-number
  A backup outbound interface is configured.
5. Run apply backup-nexthop ip-address
  A backup next hop is configured.
  - If a backup outbound interface is configured on a P2P link, no backup next hop needs to be specified.
  - If a backup outbound interface is configured on a non-P2P link, a backup next hop needs to be specified.
6. Run quit
  Return to the system view.
Enable IP FRR on the public network.
1. Run ip frr route-policy route-policy-name
  IP FRR on the public network is enabled.
  
  When using IP FRR, use this command to enable IP FRR so that the route-policy can take effect.
  
  Only one route-policy can be configured every time you use the command. If you run this command multiple times, only the latest configuration takes effect.

Verifying the Configuration

Run the display ip routing-table [ verbose ] command to check information about the IPv4 routing table.