04-18-2023 10:40 PM
Helllo All,
I have following lab setup. All routers are XRV. I am trying to understand 'fast-reroute per-prefix ti-lfa'.
XRV7
/ \
/ \
XRV4 ----------------------XRV3
/ | | \
/ | | \
XRV5 | | XRV6
\ | | /
\ | | /
XRV1------------------------XRV2
I have configured 'fast-reroute per-prefix ti-lfa level 2' on all the physical interfaces of all the routers.
But when I check 'show ip route isis' on XRV5. I see there is no (!) in front of (6.6.6.6/32) route. According to my understanding, Because I have configured 'ti-lfa' then every prefix should have alternate path. Correct ?
XRV5#show ip route isis
i L2 1.1.1.1/32 [115/10] via 100.10.50.1, 00:18:07, GigabitEthernet0/0/0/1
[115/40] via 100.40.50.4, 00:18:07, GigabitEthernet0/0/0/0 (!)
i L2 2.2.2.2/32 [115/20] via 100.10.50.1, 00:14:08, GigabitEthernet0/0/0/1
[115/30] via 100.40.50.4, 00:14:08, GigabitEthernet0/0/0/0 (!)
i L2 3.3.3.3/32 [115/30] via 100.10.50.1, 00:18:07, GigabitEthernet0/0/0/1 (!)
[115/20] via 100.40.50.4, 00:18:07, GigabitEthernet0/0/0/0
i L2 4.4.4.4/32 [115/40] via 100.10.50.1, 00:14:31, GigabitEthernet0/0/0/1 (!)
[115/10] via 100.40.50.4, 00:14:31, GigabitEthernet0/0/0/0
i L2 6.6.6.6/32 [115/30] via 100.10.50.1, 00:15:04, GigabitEthernet0/0/0/1
[115/30] via 100.40.50.4, 00:15:04, GigabitEthernet0/0/0/0
i L2 7.7.7.7/32 [115/40] via 100.10.50.1, 00:14:21, GigabitEthernet0/0/0/1 (!)
[115/20] via 100.40.50.4, 00:14:21, GigabitEthernet0/0/0/0
XRV5
-----------------
int gi0/0/0/0
ipv4 address 100.40.50.5 255.255.255.0
no sh
int gi0/0/0/1
ipv4 address 100.10.50.5 255.255.255.0
no sh
int lo0
ipv4 address 5.5.5.5 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.5555.5555.5555.5555.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 5
exit
root
commit
XRV1
-----------------
int gi0/0/0/0
ipv4 address 100.10.20.1 255.255.255.0
no sh
int gi0/0/0/1
ipv4 address 100.10.50.1 255.255.255.0
no sh
int lo0
ipv4 address 1.1.1.1 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.1111.1111.1111.1111.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/2
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 1
exit
root
commit
XRV2
-----------------
int gi0/0/0/0
ipv4 address 100.10.20.2 255.255.255.0
no sh
int gi0/0/0/1
ipv4 address 100.20.60.2 255.255.255.0
no sh
int gi0/0/0/2
ipv4 address 100.20.30.2 255.255.255.0
no sh
int lo0
ipv4 address 2.2.2.2 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.2222.2222.2222.2222.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/2
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 2
exit
root
commit
XRV3
-----------------
int gi0/0/0/0
ipv4 address 100.30.70.3 255.255.255.0
no sh
int gi0/0/0/1
ipv4 address 100.30.40.3 255.255.255.0
no sh
int gi0/0/0/2
ipv4 address 100.20.30.3 255.255.255.0
no sh
int gi0/0/0/3
ipv4 address 100.30.60.3 255.255.255.0
no sh
int lo0
ipv4 address 3.3.3.3 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.3333.3333.3333.3333.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/2
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/3
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 3
exit
root
commit
XRV4
-----------------
int gi0/0/0/0
ipv4 address 100.40.50.4 255.255.255.0
no sh
int gi0/0/0/1
ipv4 address 100.30.40.4 255.255.255.0
no sh
int gi0/0/0/2
ipv4 address 100.10.40.4 255.255.255.0
no sh
int gi0/0/0/3
ipv4 address 100.40.70.4 255.255.255.0
no sh
int lo0
ipv4 address 4.4.4.4 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.4444.4444.4444.4444.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/2
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/3
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 4
exit
root
commit
XRV6
-----------------
int gi0/0/0/1
ipv4 address 100.20.60.6 255.255.255.0
no sh
int gi0/0/0/3
ipv4 address 100.30.60.6 255.255.255.0
no sh
int lo0
ipv4 address 6.6.6.6 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.6666.6666.6666.6666.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/3
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/1
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
no int gi0/0/0/2
int lo0
passive
address-family ipv4 unicast
prefix-sid index 6
exit
root
commit
XRV7
-------------------------
int gi0/0/0/0
ipv4 address 100.30.70.7 255.255.255.0
no sh
int gi0/0/0/3
ipv4 address 100.40.70.7 255.255.255.0
no sh
int lo0
ipv4 address 7.7.7.7 255.255.255.255
exit
router isis CORE
distribute link-state level 2
is-type level-2
net 49.7777.7777.7777.7777.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls sr-prefer
exit
int gi0/0/0/3
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int gi0/0/0/0
point-to-point
address-family ipv4 unicast
fast-reroute per-prefix level 2
fast-reroute per-prefix ti-lfa level 2
exit
int lo0
passive
address-family ipv4 unicast
prefix-sid index 7
exit
root
commit
04-19-2023 12:33 AM
Hi,
The (!) is missing because of ECMP, both routes are protecting each other.
Check the output for the following commands on XRV5:
Also check the following repositories out, which have an entire lab on Segment Routing with TI-LFA at an entry level.
HTH
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