IS-IS FRR configuration example
Network requirements
As shown in Figure 45, Switch S, Switch A, and Switch D belong to the same IS-IS routing domain. Configure IS-IS FRR so that when the Link A fails, traffic can be switched to Link B immediately.
Figure 45: Network diagram
Configuration procedure
Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)
Configure IS-IS on the switches to make sure Switch A, Switch D, and Switch S can communicate with each other at Layer 3. (Details not shown.)
Configure IS-IS FRR:
Enable IS-IS FRR to automatically calculate a backup next hop, or designate a backup next hop by using a referenced routing policy.
(Method 1.) Enable IS-IS FRR to automatically calculate a backup next hop:
# Configure Switch S.
<SwitchS> system-view [SwitchS] bfd echo-source-ip 1.1.1.1 [SwitchS] isis 1 [SwitchS-isis-1] fast-reroute auto [SwitchS-isis-1] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] bfd echo-source-ip 4.4.4.4 [SwitchD] isis 1 [SwitchD-isis-1] fast-reroute auto [SwitchD-isis-1] quit
(Method 2.) Enable IS-IS FRR to designate a backup next hop by using a referenced routing policy:
# Configure Switch S.
<SwitchS> system-view [SwitchS] bfd echo-source-ip 1.1.1.1 [SwitchS] ip prefix-list abc index 10 permit 4.4.4.4 32 [SwitchS] route-policy frr permit node 10 [SwitchS-route-policy-frr-10] if-match ip address prefix-list abc [SwitchS-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface 100 backup-nexthop 12.12.12.2 [SwitchS-route-policy-frr-10] quit [SwitchS] isis 1 [SwitchS-isis-1] fast-reroute route-policy frr [SwitchS-isis-1] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] bfd echo-source-ip 4.4.4.4 [SwitchD] ip prefix-list abc index 10 permit 1.1.1.1 32 [SwitchD] route-policy frr permit node 10 [SwitchD-route-policy-frr-10] if-match ip address prefix-list abc [SwitchD-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface 101 backup-nexthop 24.24.24.2 [SwitchD-route-policy-frr-10] quit [SwitchD] isis 1 [SwitchD-isis-1] fast-reroute route-policy frr [SwitchD-isis-1] quit
Verifying the configuration
# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.
[SwitchS] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: ISIS Process ID: 1
SubProtID: 0x1 Age: 04h20m37s
Cost: 10 Preference: 10
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NBRID: 0x26000002 LastAs: 0
AttrID: 0xffffffff Neighbor: 0.0.0.0
Flags: 0x1008c OrigNextHop: 13.13.13.2
Label: NULL RealNextHop: 13.13.13.2
BkLabel: NULL BkNextHop: 12.12.12.2
Tunnel ID: Invalid Interface: Vlan-interface200
BkTunnel ID: Invalid BkInterface: Vlan-interface100
# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.
[SwitchD] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
Protocol: ISIS Process ID: 1
SubProtID: 0x1 Age: 04h20m37s
Cost: 10 Preference: 10
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NBRID: 0x26000002 LastAs: 0
AttrID: 0xffffffff Neighbor: 0.0.0.0
Flags: 0x1008c OrigNextHop: 13.13.13.1
Label: NULL RealNextHop: 13.13.13.1
BkLabel: NULL BkNextHop: 24.24.24.2
Tunnel ID: Invalid Interface: Vlan-interface200
BkTunnel ID: Invalid BkInterface: Vlan-interface101