[c-nsp] OSPF rLFA FRR - Criteria for creation of repair paths (ASR920)

[CiscoNSP List]

Hi Everyone - Apologies for the long post, and hope the ascii diag retains shape! Im hoping someone can explain what process a router goes through when deciding to create repair paths/tunnel....and how it decides how "many" it will create.

I have the following setup, and just trying to understand how the routers (In this case 4 x ASR920s, 2 ME3600's) made the descions they did.

7200 then has a link to an ASR1006 (No FRR running, just OSPF)

My main issue is that I want the link to the 7200 only used if the we have multiple failures...eg both 10G links between the ASR920s failed.

Currently, ASR920-A uses direct TenG link as best path->ASR920-C and direct 1Gb link as best path to ASR920-B, and link to 7200 as repair path (Which I dont want :) )....each other destination has an equal cost path via TenG + Gb (Again, something I need to fix, so that 10G is primary, 1Gb is repair)


Hopefully the ascii diag retains shape :)


Numbers in brackets are OSPF cost.


7200 (Not running FRR, just OSPF)
|
|
1G (250)
|
|
ASR920-A-------1G (2)--------ASR920-B
|                    |
|                    |
10G (220)     10G (220)
|                    |
|                    |
ASR920-C-------1G (2)--------ASR920-D
|                 |
|                 |
1G (5)      1G (5)
|                 |
|                 |
ME3600-A-------1G--------ME3600-B
|                 |
|                 |
------------ASR1006-------------


So from the above setup, it has created the following repair paths:


ASR920-A

Only one tunnel -> ASR920-D via 1G link to ASR920-B

ASR920-B

Tunnel 1 -> ASR920-C via 1G link to ASR920-A
Tunnel 2 -> ASR920-C via TenG link to ASR920-B

ASR920-C

Tunnel 1 -> ASR920-D via 1G link to ASR920-D
Tunnel 2 -> ASR920-B via 1G link to ASR920-D

ASR920-D

Tunnel 1 -> ASR920-C via 1G link to ASR920-C
Tunnel 2 -> ASR920-A via 1G link to ASR920-C

ME3600-A

Tunnel 1 -> ASR920-D vi 1G link to ME3600-B
Tunnel 2 -> ME3600-B vi 1G link to ME3600-B

ME3600-B

Tunnel 1 -> ASR920-C vi 1G link to ME3600-B
Tunnel 2 -> ME3600-B vi 1G link to ME3600-B


Thanks in advance!