BFD and trunks

[glsparks]

So i have a number of 3850s running ipservicesk9 with multiple vrfs.

The switch has two SVI's that are trunked to another device e.g VLAN 10,20 with each VLAN being a layer 3 interface within a separate vrf.

vlan 10

vrf forwarding RED

ip add x.x.x.x

e.g int g1/0/24 switchport trunk 10,20

I am experiencing BFD flapping which is tearing down my BGP sessions for both BGP peers.

Continually seeing $BFDFSM-6-BFD_SESS_DOWN in the logs

Have confirmed no physical issues with the cabling the connection is 1000-BaseT

Interfaces on both devices are not showing any errors, drops or high utilisation.

A BFD template has been applied to both VLAN interfaces. No BFD config applied to the physical interfaces.

int vlan 10,20

bfd-template single-hop BFD-TEMPLATE
interval min-tx 500 min-rx 500 multiplier 3

Any ideas what this could be? I am suspecting a bug in the code 16.12. Or is the BFD configuration to blame?

[Reza Sharifi]

Hi,

Could you try adding the BFD to the physical interface instead of the VLAN and testing again?

BFD is more for tearing down the physical interface than a logical interface (VLAN).

HTH

[MHM Cisco World]

why two vlan ? why not only one, the one that use as bgp update source and neighbor 

MHM

[glsparks]

Two VLANs as they are each in different VRFs. 

[MHM Cisco World]

Can I see bgp config

MHM

[glsparks]

Looks like the issue is hardware related. The far end is a Palo and it is reporting interface errors.