BGP fast reroute is a feature that brings together indirection techniques in the forwarding plane and pre-computation of BGP backup paths in the control plane to support fast reroute of BGP traffic around unreachable/failed BGP next-hops. BGP fast reroute is supported with IPv4, label-IPv4, IPv6, label-IPv6, VPN-IPv4 and VPN-IPv6 routes. The scenarios supported by the base router BGP context are described in Table: BGP fast reroute scenarios (base context).
See the VPRN section of the 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 3 Services Guide: IES and VPRN for more information about BGP fast reroute information specific to IP VPNs.
| Ingress packet | Primary route | Backup route | Prefix independent convergence |
|---|---|---|---|
IPv4 |
IPv4 route with next-hop A resolved by an IPv4 route or any shortcut tunnel |
IPv4 route with next-hop B resolved by an IPv4 route or any shortcut tunnel |
Yes |
IPv4 |
Label-IPv4 route with next-hop A resolved by any transport tunnel |
Label-IPv4 route with next-hop B resolved by any transport tunnel |
Yes, but if the label-IPv4 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |
IPv4 |
Label-IPv4 route with next-hop A resolved by a local route |
Label-IPv4 route with next-hop B resolved by a local route |
Yes, but if the label-IPv4 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |
IPv4 |
Label-IPv4 route with next-hop A resolved by a static route |
Label-IPv4 route with next-hop B resolved by a static route |
Yes, but if the label-IPv4 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |
IPv6 |
IPv6 route with next-hop A resolved by an IPv6 route |
IPv6 route with next-hop B resolved by an IPv6 route |
Yes |
IPv6 |
Label-IPv6 route with next-hop A resolved by any transport tunnel |
Label-IPv6 route with next-hop B resolved by any transport tunnel |
Yes, but if the label-IPv6 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |
IPv6 |
Label-IPv6 route with next-hop A resolved by a local route |
Label-IPv6 route with next-hop B resolved by a local route |
Yes, but if the label-IPv6 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |
IPv6 |
Label-IPv6 route with next-hop A resolved by a static route |
Label-IPv6 route with next-hop B resolved by a static route |
Yes, but if the label-IPv6 routes are label-per-prefix, the ingress card must be IOM3 or better for PIC |