Backup Path based on Route-Map Prefixes
R1
Route-map and access-list configuration:
(config)#ip access-list 1 | Create an access-list |
(config-ip-acl)#permit any 40.40.40.0 0.0.0.255 any | Configuring rule to permit only one prefix |
(config)#route-map rmap1 permit 1 | Create a route-map |
(config-route-map)#match ip address 1 | Apply above created access-list in route-map |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config)#exit | Exit config mode. |
Apply the above created route-map with fast-reroute:
(config)#router isis 1 | Create an IS-IS routing instance for area 49 with instance 1 |
(config-router)#fast-reroute per-prefix level-1 proto ipv4 route-map rmap1 | Configure LFA-FRR to calculate the available backup path for routes allowed through route-map |
(config-if)#commit | Commit candidate configuration to the running configuration |
(config-router)#exit | Exit router mode. |
(config)#exit | Exit config mode. |
Validation
R1#show ip route
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2,
ia - IS-IS inter area, E - EVPN,
v - vrf leaked
* - candidate default
IP Route Table for VRF "default"
C 10.10.10.0/24 is directly connected, eth1, 01:02:04
C 10.12.30.0/24 is directly connected, eth0, 02:01:45
C 20.20.20.0/24 is directly connected, eth2, 01:02:04
C 30.30.30.0/24 is directly connected, eth3, 01:02:04
i L1 40.40.40.0/24 [115/10] via 10.10.10.141, eth1, 00:35:32
i L1 50.50.50.0/24 [115/15] via 20.20.20.143, eth2, 00:35:45
i L1 60.60.60.0/24 [115/15] via 10.10.10.141, eth1, 00:35:32
C 127.0.0.0/8 is directly connected, lo, 02:01:45
Gateway of last resort is not set
R1#show ip isis route fast-reroute
Tag : 1 VRF : default
Codes : L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area,
D - discard, LP - Link Protecting, NP - Node Protecting,
BP - Broadcast Interface Disjoint, Pri - Primary Path,
Sec - Secondary Path, DP - Downstream Path
L1 40.40.40.0/24
Primary Path via : 10.10.10.141, eth1
FRR Backup Path via : 30.30.30.144, eth3
FRR Metric : 25
Protection Provided : LP NP BP
R1#show ip route fast-reroute
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area ,p - stale info
* - candidate default
IP Route Table for VRF "default"
i L1 40.40.40.0/24 [115/10] via 10.10.10.141, eth1, 00:35:48
[FRR-NH] via 30.30.30.144, eth3 FRR Table has only allowed prefix through route-map , for remaining prefixes, FRR not present