Hello,
I was troubleshooting an MPLS inter-area tunnel that was working fine
yesterday. I loaded my saved configs this morning and the tunnels were down.
The topology is as follows:
R7---R6 = area 876
R7---R8 = area 876
R8---R6 = area 0
Basically a full mesh of 3 routers with the R6/R8 link in area 0. R6/R8
loopbacks are in area 0 as well. There is an explicit tunnel from R7 that
goes through R6 on towards R8. The tunnel is configured with an explicit
path:
R7#sho run int tun 78
interface Tunnel78
ip unnumbered Loopback0
tunnel destination 6.7.8.8
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng path-option 1 explicit name R7-R8
R7#sho ip explicit-paths
PATH R7-R8 (loose source route, path complete, generation 4)
1: next-address 192.168.76.6 <---R7/R6 link in area 876
2: next-address loose 192.168.86.8 <---R6/R8 link in area 0
During troubleshooting I noticed the TE metric was listed as invalid in "sho
mpls traffic-eng topology"
IGP Id: 6.7.8.7, MPLS TE Id:6.7.8.7 Router Node (ospf 1 area 876)
link[0]: Point-to-Point, Nbr IGP Id: 6.7.8.6, nbr_node_id:2, gen:3
frag_id 0, Intf Address:192.168.76.7, Nbr Intf
Address:192.168.76.6
TE metric:invalid, IGP metric:10, attribute flags:0x0
physical_bw: 100000 (kbps), max_reservable_bw_global: 75000 (kbps)
max_reservable_bw_sub: 0 (kbps)
So I change the path-selection method to IGP and the path came up.
R7(config)#int tun 78
R7(config-if)#tunnel mpls traffic-eng path-selection metric igp
01:28:06: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel78, changed
state to up
I can't find much information about why the TE metric was invalid, and I
never ran into this before. So I switched the path-selection metric back to
te and the tunnel stayed up, even after shutting/no shutting.
My question is: What gives? Why is the TE metric listed as invalid? And why
did switching the path-selection method to igp make the tunnel come up but
switching it back not make it go down?
Thanks,
--
Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
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