IS-IS FRR configuration example
Network requirements
As shown in Figure 50, Switch A, Switch B, and Switch C 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 50: Network diagram
Table 15: Interface and IP address assignment
Device | Interface | IP address | Device | Interface | IP address |
|---|---|---|---|---|---|
Switch A | Vlan-int100 | 12.12.12.1/24 | Switch B | Vlan-int101 | 24.24.24.4/24 |
Vlan-int200 | 13.13.13.1/24 | Vlan-int200 | 13.13.13.2/24 | ||
Loop0 | 1.1.1.1/32 | Loop0 | 4.4.4.4/32 | ||
Switch C | Vlan-int100 | 12.12.12.2/24 | |||
Vlan-int101 | 24.24.24.2/24 |
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 B, and Switch C can communicate with each other at Layer 3. (Details not shown.)
Configure IS-IS FRR:
Enable IS-IS FRR to calculate a backup next hop through LFA calculation, or designate a backup next hop by using a referenced routing policy.
(Method 1.) Enable IS-IS FRR to calculate a backup next hop through LFA calculation:
# Configure Switch A.
<SwitchA> system-view [SwitchA] isis 1 [SwitchA-isis-1] address-family ipv4 [SwitchA-isis-1-ipv4] fast-reroute lfa [SwitchA-isis-1-ipv4] quit [SwitchA-isis-1] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] isis 1 [SwitchB-isis-1] address-family ipv4 [SwitchB-isis-1-ipv4] fast-reroute lfa [SwitchB-isis-1-ipv4] quit [SwitchB-isis-1] quit
(Method 2.) Enable IS-IS FRR to designate a backup next hop by using a referenced routing policy:
# Configure Switch A.
<SwitchA> system-view [SwitchA] ip prefix-list abc index 10 permit 4.4.4.4 32 [SwitchA] route-policy frr permit node 10 [SwitchA-route-policy-frr-10] if-match ip address prefix-list abc [SwitchA-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface 100 backup-nexthop 12.12.12.2 [SwitchA-route-policy-frr-10] quit [SwitchA] isis 1 [SwitchA-isis-1] address-family ipv4 [SwitchA-isis-1-ipv4] fast-reroute route-policy frr [SwitchA-isis-1-ipv4] quit [SwitchA-isis-1] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] ip prefix-list abc index 10 permit 1.1.1.1 32 [SwitchB] route-policy frr permit node 10 [SwitchB-route-policy-frr-10] if-match ip address prefix-list abc [SwitchB-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface 101 backup-nexthop 24.24.24.2 [SwitchB-route-policy-frr-10] quit [SwitchB] isis 1 [SwitchB-isis-1] address-family ipv4 [SwitchB-isis-1-ipv4] fast-reroute route-policy frr [SwitchB-isis-1-ipv4] quit [SwitchB-isis-1] quit
Verifying the configuration
# Display route 4.4.4.4/32 on Switch A to view the backup next hop information.
[SwitchA] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: IS_L1
Process ID: 1
SubProtID: 0x1 Age: 04h20m37s
Cost: 10 Preference: 10
IpPre: N/A QosLocalID: N/A
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NibID: 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
FtnIndex: 0x0 TrafficIndex: N/A
Connector: N/A
# Display route 1.1.1.1/32 on Switch B to view the backup next hop information.
[SwitchB] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
Protocol: IS_L1
Process ID: 1
SubProtID: 0x1 Age: 04h20m37s
Cost: 10 Preference: 10
IpPre: N/A QosLocalID: N/A
Tag: 0 State: Active Adv
OrigTblID: 0x0 OrigVrf: default-vrf
TableID: 0x2 OrigAs: 0
NibID: 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
FtnIndex: 0x0 TrafficIndex: N/A
Connector: N/A