BFD + static route + sub interface

[Luca CQ]

Hi all

Question about this scenario:
ASR 1009-X , IOS_XE linked to another router by interface g0/1.
Customer has vrf TEST and wants 2 subnet p2p/31 configured on sub-interfaces as follows:

g0/1.10  --> ip adrr 10.10.10.1/31   (other router has .2)
g0/1.20  --> ip adrr 20.20.20.1/31   (other router has .2)

Need to configure BFD.
Questions are:
1) the BFD route static config can (or have to) be bold to sub-int ?   (i didn't found examples in Cisco BFD config Guides)
2) does it need to be bold to VRF TEST?    (i've doubt because the next hop is in VRF TEST)
3) is it enough to config only one static? or must be configured both?    (i've doubt because the physical interface is the same g0/1)

Is this configuration correct?:

ip route static bfd  g0/1.10  10.10.10.2 
ip route static bfd  g0/1.20  20.20.20.2 

ip route vrf TEST  1.1.1.0  255.255.255.0   g0/1.10  10.10.10.2 
ip route vrf TEST  2.2.2.0  255.255.255.0   g0/1.20  20.20.20.2 

thanks a lot to anyone who will reply

Luca

[balaji.bandi]

Not sure if i understand correctly bare with me, if both are the same VRF, why do you need static routing ?

have this sub-interface configured with VRF interface - what config you have ?

why do you need BFD what is the use case here ?

check some references:

https://community.cisco.com/t5/service-providers-knowledge-base/bfd-support-on-cisco-asr9000/ta-p/3153191

[MHM Cisco World]

I dont get what try here 
the next-hop is direct connect and you use egress interface why BFD ?

[Luca CQ]

Hello  @balaji.bandi  , @MHM Cisco World  and thanks for your replies

yes sub-interfaces are in the same VRF TEST:

g0/1.10 --> ip adrr 10.10.10.1/31, vrf forwarding TEST, encap dot1q 10, etc          (remote router has 10.10.10.2)
g0/1.20 --> ip adrr 20.20.20.1/31, vrf forwarding TEST, encap dot1q 20, etc          (remote router has 20.20.20.2)

but the subnet to reach are:
1.1.1.0/24
2.2.2.0/24
that are the subnet assigned to the platforms that are "behind" the remote router that has the other ip addresses (the .2) of the two p2p/31, and customer askes for static routing through those subif/vlans (10 and 20) + BFD to check and manage this reachability, may be a switch in the middle actually i don't know

[MHM Cisco World]

Yes I get 
I will run lab 
first you have VRF 
second you have subinterface 

[MHM Cisco World · Accepted solution]

hostname IOU1
!
ip vrf MHM
rd 1:100
!
interface Ethernet0/0
no ip address
!
interface Ethernet0/0.10
encapsulation dot1Q 10
ip vrf forwarding MHM
ip address 10.0.0.10 255.255.255.0
bfd interval 50 min_rx 50 multiplier 3
!
interface Ethernet0/0.20
encapsulation dot1Q 20
ip vrf forwarding MHM
ip address 20.0.0.10 255.255.255.0
bfd interval 50 min_rx 50 multiplier 3
!
ip route static bfd Ethernet0/0.10 10.0.0.20
ip route static bfd Ethernet0/0.20 20.0.0.20
ip route vrf MHM 22.22.22.22 255.255.255.255 Ethernet0/0.10 10.0.0.20
ip route vrf MHM 33.33.33.33 255.255.255.255 Ethernet0/0.20 20.0.0.20

I run this lab for you 

hope it help you 

[Luca CQ]

hi @MHM Cisco World , thank you!
so it works with subinterfaces in the

ip route static bfd 

commands, great

thank you for your support and time