Enabling the Capability of Exchanging Labeled IPv4 Routes

To establish an inter-AS BGP LSP, enable labeled IPv4 route exchange between ASBRs.

Procedure

Create a routing policy.
Perform the following steps on ASBRs:
1. Access the system view.
```
system-view
```
2. Configure a routing policy to be applied to advertise routes to the remote ASBR.
```
route-policy route-policy-name permit node seq-number
```
3. Distribute labels for IPv4 routes.
```
apply mpls-label
```
4. Return to the system view.
```
quit
```
Apply a routing policy.
Perform the following steps on ASBRs:
1. Access the system view.
```
system-view
```
2. Access the BGP view.
```
bgp { as-number-plain | as-number-dot }
```
3. Configure a routing policy to be applied to advertise routes to the remote ASBR.
```
peer ipv4-address route-policy route-policy-name export
```
4. Return to the system view.
```
quit
```
Enable labeled IPv4 route exchange.
Perform the following steps on ASBRs:
1. Access the system view.
```
system-view
```
2. Access the view of the interface connecting the remote ASBR.
```
interface interface-type interface-number
```
3. Enable the MPLS function.
```
mpls
```
4. Return to the system view.
```
quit
```
5. Access the BGP view.
```
bgp { as-number-plain | as-number-dot }
```
6. Configure labeled IPv4 route exchange with the remote ASBR.
```
peer ipv4-address label-route-capability [ check-tunnel-reachable ]
```
  - If tunnel reachability checking is enabled, BGP advertises IPv4 unicast routes to peers when routed tunnels are unreachable or advertises labeled routes to peers when routed tunnels are reachable. This eliminates the risk of establishing an MP-EBGP peer relationship between PEs over a faulty LSP because this will cause data forwarding failures.
  - If tunnel reachability checking is disabled, BGP advertises labeled routes to peers whether the tunnels for imported routes are reachable or not.
(Optional) Set the maximum number of labeled BGP routes for load balancing.
After load balancing is configured among labeled BGP routes on the ASBR, they can load-balance traffic as long as equal-cost labeled BGP routes exist, which improves network bandwidth utilization.
1. Access the system view.
```
system-view
```
2. Access the BGP view.
```
bgp { as-number-plain | as-number-dot }
```
3. (Optional) Access the BGP-IPv4 unicast address family view.
```
ipv4-family unicast
```
4. Set the maximum number of labeled BGP routes for load balancing.
```
maximum load-balancing number
```
  By default, the maximum number of labeled BGP routes for load balancing is 1.
5. (Optional) Select BGP labeled routes regardless of their IGP metric values.
```
bestroute igp-metric-ignore
```
  By default, BGP labeled routes with the same destination but different next-hop metric values cannot balance traffic. To enable these routes to balance traffic, run the bestroute igp-metric-ignore command. After this command is run, routes can be selected to balance traffic, regardless of their IGP metric values. Exercise caution when using this command.