BFD between ASR9001 IOS XR and ACI border leaf (4.2(6d)

[csco10260962]

Has anyone setup a working BFD session between cisco ACI and an IOS XR 9K for a directely connected EBGP peer via routed sub interfaces ? min int 50 multiplier 3 on both ACI and on IOS XR. IBGP with BFD between 2 ios xr routers connected to two different border leafs work in multipod setup. IBGP is formed on the loppback addresses. EBPG connection from IOS XR to the border leaf is also up. But as soon as i enable BFD on the bgp l3out and peer connection profile to the XR router and i enable bfd fastdetect under the neighbor config the ebgp session starts flapping because of bfd dampening. Logging shows BFD echo request fails but ping between ACI and IOS XR interfaces works.

[csco10260962 · Accepted solution]

After some testing i got this working :

On IOS XR i had to add the following config for example :

bfd

interface TenGigE0/0/1/0.3607 echo ipv4 source 10.14.0.12

and i had to do that for each uplink from ios xr router to the aci leafs.

And then after enabling bfd fastdetect under the ACI neighbor and also enabling bfd under the bgp peer connectivity profile the bfd session stayed stable and didn't flap constant from up to down.