If you haven't already, you will need to edit the rp_filter flag in linux. Setting this to "2" (commonly called RPF Loose) may help with your routing issue. Let me know if you have any questions or issues.

https://www.slashroot.in/linux-kernel-rpfilter-settings-reverse-path-filtering


/Charles van Niman

On Tue, Apr 24, 2018 at 9:16 AM, knet solutions <knetsolutions2@gmail.com> wrote:

All,

I am facing a strange issue (all routers are linux with bird runnning).
My topology(RING Topology) is as below,


R1 ------------R2------------R3---------R4

BGP is running on all nodes.

R1 to R3 route is going via R1--R2--R3 and the return path is in also in same path (R3--R2----R1), then  thing works fine

But suppose,

R1 to R3 path is  R1---R2---R3 and  return path is  R3----R4---R1.  then  traffic is not passing.

Any configurations i should do in linux ?