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Policy based routing, local traffic ASR IOS-XR

als95
Level 1
Level 1

How can I aply something like PBR but for the traffic originated from the router interface itself in a multi-homed setup? See the diagram attached.

I have 10.0.0.1/31 configured on TenGigE0/0/0/1. I would like ping replies to ping requests to that IP always returned via the same TenGigE0/0/0/1.

At that moment I receive pings from 192.18.1.1 and bgp table has TenGigE0/0/0/5 a best route. This is not a desired behavior since traffic should be returned via TenGigE0/0/0/1 where 10.0.0.0/31 is located.

Is there a way on IOS-XR to apply Policy Based Routing to locally generated packets?

 

22 Replies 22

Hello
quite understand you wish symmetric routing but as i have stated traffic engineering with PBR would mostly probably not provide this - so unless you can elaborate on your existing network topology regards what routing processes / traffic engineering/egress paths etc you are currently utilising then supplying an alternative solution would be inappropriate.


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

Attached the network diagram.

 

I run lab and test your topology, 
the R1 use local PBR and send traffic via F1/1 (RIB is use f0/0) 
the R1 success use Local PBR and send traffic the return is not via f1/1 it via f0/0 
the return traffic is control by R2 not by R1.
@paul driver  remember the issue of NAT days ago, check the Echo request (no response found) so as I mention that issue because of routing.
thanks all
MHM

Screenshot (675).png

How to apply local PBR on IOSXR? Please provide the command you have used in your lab.

 

Hello @MHM Cisco World 
What you have posted would produce that result, I am on about a more complex network or in the diagram the OP has posted in that the rtr has dual paths into the internet.

Where ever that destination is within the internet, it possible the receiving rtr prefers to route via a different path back to the OPs rtr, So when the OPs rtr is PBR'd via its alternate path or in your case  PBR'd via rtr2 , the request is forwarded to the "another" rtr on the internet as such when that rtr responds it may have a more preferred path to reach back to the source network.

In your case it will be to rtr1 other than r2 or in the OPs case via its primary interface where I believe uRPF is enabled in either scenario this is where asymmetric routing could possibly be produced, plus the OPs rtr will drop traffic because of strict uRPF being enabled.


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

Was a solution ever found for IOS XR ? or is it not possible to change the next hop for traffic localy generated on a IOX XR router ? 

i have a GRE tunnel where the tunnel destination address should take another path than it would when looking into the FIB

There is no solution. There is no way to apply Policy Based Routing to the locally generated packets on ASR routers.

danhed7400
Level 1
Level 1

 

Was a solution ever found for IOS XR ? or is it not possible to change the next hop for traffic localy generated on a IOX XR router ? 

i have a GRE tunnel where the tunnel destination address should take another path than it would when looking into the FIB

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