Issue with Backup NNHOP TE Tunnel with Auto-Tunnel Backup !

Unanswered Question
May 17th, 2010

Hi All

I am trying to implement NNHOP Backup Tunnel(Manual) to achieve Node Protection. The Network Topology is attached along with.

I am using TE Auto-Tunnel to achieve Link Protection via Dynamic Backup Tunnels.

I am building NNHOP Tunnel from core1.pop1( to core1.pop2( and One Hop Dynamic Primary and Backup Auto-TE Tunnels are being dynamically between the core routers .

I have kep the autoroute metric for NNHOP TE Tu100 more so that under normal no problem condition traffic between edge routers does not flows across this path as Tu100 will be preferred without altering for all the routes learnt behind them

Now the problem is for Node Protection when core2.pop2 is down, the traffic gets rerouted via core2.pop1 but not over Backup NNHOP Tunnel and instead over the the Primary Auto-Tunnel (as they have better metric) between core1.pop1 and core2.pop1 and core2.pop1 and core1.pop2. The Traffic is still flowing between my edge routers but not over my desired LSP..

I am not able to control this beahviour as if I don;t alter the metric for NNHOP TE Tu100 all my traffic starts flowing across them during normal no problem conditions too.

Any suggestions how to optimise the traffic flow ?


Vaibhava Varma

I have this problem too.
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Olivier ARRIGHI Mon, 05/17/2010 - 17:17

Hi Vaibhava,

have you considered not using auto tunnel? i'd rather go for manual static primary and backup tunnels with FRR.There you will have all the control you need.Path protection could also be and option if you do not require FRR convergence times

my 2 cents


Vaibhava Varma Tue, 05/18/2010 - 02:14

Hi Olivier

I am not considering Manual Primary Tunnel for now. WIll give it a thought later.

Meanwhile I have achived the solution for my above problem using event manager applet. Everything is working fine now.

Also I don't think Manual or Auto-Tunnel will make any difference as the underlying issue here is presence of a Primary NHOP Tunnel towards backup

core router  in the path of NNHOP Tunnel which is causing the NNHOP Tunnel to be not preferred. The only way it seems to solve this issue to me is to not have any Primary Tunnel NHOP Tunnel between the PLR and Backup Core Router.


Vaibhava Varma


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