[c-nsp] ME3600 : BFD for BGP running on EVC interface in an VRF

[Adam Vitkovsky]

Hi Amos,

> Amos Thong
> Sent: Thursday, February 04, 2016 3:59 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] ME3600 : BFD for BGP running on EVC interface in an VRF
>
> Hi Cisco-NSP Member ?
>
>
>
> Have anyone in the forum ever put an SVI/EVC interface in a VRF and do BGP
> with BFD ?
>
> We made everything work except BFD.  Cisco document at
> http://products.mcisco.com/c/en/us/products/collateral/switches/me-
> 3800x-series-carrier-ethernet-switch-routers/product_bulletin_c25-
> 683297.html indicates it support BFD on SVI but did no mentioned if it works
> in a VRF.
>
>
> Our config is as follow, everything seems right but BFD just wont come up.
>
>
> Some advise would be appreciated. Thanks.
>
>
> regards
>
> Amos
>
>
>
> Interface facing Partner.
> ==========================================================
> ===========
> platform bfd allow-svi
> interface GigabitEthernet0/1
>  switchport trunk allowed vlan none
>  switchport mode trunk
>  mtu 9178
>  no cdp enable
>  hold-queue 2000 in
>   service instance 1 ethernet
>   encapsulation dot1q 2501
>   rewrite ingress tag pop 1 symmetric
>   bridge-domain 2501
> vlan 2501
>
> Terminating directly into VRF
> ---------------------------------------------------
> interface Vlan2501
>  ip vrf forwarding VRF-VOIP                <<<<<<<<<
>  mtu 9178
>  bandwidth 1000000000
>  ip address 211.25.x.x 255.255.255.252
>  no ip redirects
>  no ip unreachables
>  no ip proxy-arp
>  bfd interval 250 min_rx 250 multiplier 3      <<<<<< Enable BFD.
>  hold-queue 2000 in
>
>
> The following config will make the router to be advertised as a VPNv4 route
> to be advertised to the RR.
> ----------------------------------------------------------------------------------------------
> ---
> router bgp 1234
>   address-family ipv4 vrf VRF-VOIP
>   network 211.25.z.z mask 255.255.255.252
>   exit-address-family
> ip route vrf VRF-VOIP 211.25.z.z 255.255.255.252 Null 0
>
>
> BGP config with Partner
> -----------------------------
> router bgp 1234
>  address-family ipv4 vrf VRF-VOIP
>   neighbor 211.25.y.y description eBGP Session with telecom (AS4321)
>   neighbor 211.25.y.y inherit peer-session voip-nni-telecom
>   neighbor 211.25.y.y advertisement-interval 0        <<<<< Configured but not
> displayed, 0 is the def.
>   neighbor 211.25.y.y fall-over bfd single-hop
>   neighbor 211.25.y.y activate
>   no auto-summary
>   no synchronization
>   exit-address-family
>
> template peer-session voip-nni-telecom
>   description eBGP Session with telecom
>   remote-as 4321
>   version 4
>   timers 7 21
>   fall-over
>  exit-peer-session
>
> Verification : Show BGP neighbour status in VRF
> --------------------------------------------------
> vi-01-siteA#show bgp vrf VRF-VOIP all summary For address family: IPv4
> Unicast <<<<<<Snippe output>>>>>>>>>>>>>>>>
> Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down
> State/PfxRcd
> 211.25.y.y   4         4321   16558   16992 28744203    0    0 5d09h           2           <<<<<
> BGP session in VRF is good and exchanging routes
>
>
> Verfication : BFD function is down.
> -------------------------------------
> vi-01-siteA#show bfd nei
> IPv4 Sessions
> NeighAddr                              LD/RD         RH/RS     State     Int
> 211.25.y.y                           5/0          Down      Down      Vl2501        <<<<< BFD just
> wont come up !!!
> vi-01-siteA#
>
> vi-01-siteA#show bfd neighbors details
>
> IPv4 Sessions
> NeighAddr                              LD/RD         RH/RS     State     Int
> 211.25.y.y                           5/0          Down      Down      Vl2501
> Session Host: Software
> OurAddr: 211.25.x.x
> Handle: 2
> Local Diag: 0, Demand mode: 0, Poll bit: 0
> MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3 Received MinRxInt: 0,
> Received Multiplier: 0 Holddown (hits): 0(0), Hello (hits): 1000(598) Rx Count:
> 0, Rx Interval (ms) min/max/avg: 0/0/0 last: -1 ms ago Tx Count: 598, Tx
> Interval (ms) min/max/avg: 760/1000/883 last: 12 ms ago Elapsed time
> watermarks: 0 0 (last: 0) Registered protocols: BGP CEF
> Last packet: Version: 1                  - Diagnostic: 0
>              State bit: AdminDown        - Demand bit: 0
>              Poll bit: 0                 - Final bit: 0
>              C bit: 0
>              Multiplier: 0               - Length: 0
>              My Discr.: 0                - Your Discr.: 0
>              Min tx interval: 0          - Min rx interval: 0
>              Min Echo interval: 0
> ------------------------------------------------------------end of document------------

According to the above output you are not receiving any BFD messages.
And also since BGP came up it is probably not registered with BFD anyways.
Just shooting in the dark:
Try to remove fall-over from the peer session
And configure only fall-over bfd on the neighbour statement (i.e. without the one hop)
Also what does the debug says please?


adam



        Adam Vitkovsky
        IP Engineer

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