When MPLS TE tunnel is configured between head end and tail end, the tunnel destination should match the TE router ID of the other end. If not the router will assume that it doesn’t have a valid path to the destination and RSVP will not be triggered. This will end up in tunnel remaining down.
A quick example will reveal the same,
R2#sh run
Building configuration...
Current configuration : 2442 bytes
!
ip cef
mpls traffic-eng tunnels
!
!
!
interface Loopback0
ip address 150.1.2.2 255.255.255.255
no ip directed-broadcast
!
interface Tunnel29
ip unnumbered Loopback0
no ip directed-broadcast
tunnel destination 9.9.9.9
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute metric absolute 100
tunnel mpls traffic-eng priority 7 7
tunnel mpls traffic-eng bandwidth 10000
tunnel mpls traffic-eng path-option 1 explicit name EXP
interface FastEthernet0/1
ip address 150.1.29.2 255.255.255.0
no ip directed-broadcast
duplex full
speed 100
mpls traffic-eng tunnels
tag-switching ip
ip rsvp bandwidth 50000
router ospf 1
mpls traffic-eng router-id Loopback0
mpls traffic-eng area 0
router-id 150.1.2.2
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 0
ip explicit-path name EXP enable
next-address 150.1.29.9
next-address 9.9.9.9
!
!
tag-switching tdp router-id Loopback0 force
end
R2#
On R9, we have 2 loopback interfaces loopback0 and loopback9 configured. We use one loopback interface as TE router ID and use other loopback for tunnel ip address as below,
R9#show run
Building configuration...
Current configuration : 2585 bytes
ip cef
mpls traffic-eng tunnels
!
!
!
interface Loopback0
ip address 150.1.9.9 255.255.255.255
no ip directed-broadcast
!
interface Loopback9
ip address 9.9.9.9 255.255.255.255
no ip directed-broadcast
interface Tunnel29
ip unnumbered Loopback9
no ip directed-broadcast
tunnel destination 150.1.2.2
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng autoroute metric absolute 100
tunnel mpls traffic-eng priority 7 7
tunnel mpls traffic-eng bandwidth 10000
tunnel mpls traffic-eng path-option 1 dynamic
!
interface FastEthernet0/1
ip address 150.1.29.9 255.255.255.0
no ip directed-broadcast
duplex full
speed 100
mpls traffic-eng tunnels
tag-switching ip
ip rsvp bandwidth
router ospf 1
mpls traffic-eng router-id Loopback0
mpls traffic-eng area 0
router-id 150.1.9.9
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 0
!
!
ip explicit-path name EXPLICIT enable
next-address 150.1.29.2
next-address 150.1.12.1
next-address 150.1.13.3
next-address 150.1.34.4
next-address 150.1.46.6
next-address 150.1.6.6
!
!
tag-switching tdp router-id Loopback0 force
end
R9#
With the above configuration, the tunnel at R9 will be up as the tunnel destination configured on R9 matches the TE router ID of R2.
R9#show int tun 29 | inc line protocol
Tunnel29 is up, line protocol is up
R9#
R9#show mpls traffic-eng tunnels tunnel 29
Name: R9_t29 (Tunnel29) Destination: 150.1.2.2
Status:
Admin: up Oper: up Path: valid Signalling: connected
R9#
But on R2, the tunnel will be down, as the tunnel destination configured on R2 tunnel doesn’t match R9’s TE router ID.
R2#show int tunnel 29 | inc line protocol
Tunnel29 is up, line protocol is down
R2#show mpls traffic-eng tunnel tunnel 29
Name: R2_t29 (Tunnel29) Destination: 9.9.9.9
Status:
Admin: up Oper: down Path: not valid Signalling: Down
path option 1, type explicit EXP
Last Error: PCALC:: Destination IP address, 9.9.9.9, not found
R2#
Now changing the TE router ID will solve the issue and bring the tunnel up.
R9(config)#router ospf 1
R9(config-router)#mpls traffic-eng router-id loopback 9
R9(config-router)#end
R9#
R2#show interface tunnel 29 | inc line protocol
Tunnel29 is up, line protocol is up
R2#
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