BFD peer is Down, BGP fall-over

[sebastien3]

Hello,

I have a problem to enable BFD over BGP between two routers.

Here is the configuration on one of the routers (R1). The configuration is identical on R2 except the IP addresses !

interface Loopback0
 ip address 192.168.100.1 255.255.255.255
!
interface Port-channel1
 description *** ONLY FOR EIGRP ***
 no ip address
 no negotiation auto
!
interface Port-channel1.42
 description *** EIGRP TO R2 ***
 encapsulation dot1Q 42
 ip address 10.0.0.1 255.255.255.252
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 bfd interval 750 min_rx 750 multiplier 3
!
router eigrp 1
 bfd interface Port-channel1.42
 network 192.168.100.1 0.0.0.0
 network 10.0.0.0 0.0.0.3
 passive-interface default
 no passive-interface Port-channel1.42
 eigrp router-id 192.168.100.1
!
router bgp 1234
 bgp router-id 192.168.100.1
 bgp log-neighbor-changes
 neighbor 192.168.100.2 update-source Loopback0
 neighbor 192.168.100.2 remote-as 1234
 neighbor 192.168.100.2 fall-over bfd
 !
 address-family ipv4
  network 192.168.100.0 mask 255.255.255.0
  neighbor 192.168.100.2 activate
  neighbor 192.168.100.2 next-hop-self
  neighbor 192.168.100.2 soft-reconfiguration inbound
  neighbor 192.168.100.2 route-map SET_LOCALPREF in
 exit-address-family
!

BFD process :

R1#sh bfd neighbors

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
10.0.0.2                          4097/4099       Up        Up        Po1.42


R1#sh ip bgp neighbors 192.168.100.2
BGP neighbor is 192.168.100.2,  remote AS 1234, internal link
 Description:
 Fall over configured for session
 BFD is configured. BFD peer is Down. Using BFD to detect fast fallover (multi-hop).

Do you have any idea of ​​"BFD is configured. BFD peer is Down" problem ?

Thank you

[pman]

Hi,

I suggest you take a look at the following guide that explains BFD — BGP Multihop:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-3s/irg-xe-3s-book/bfd-bgp-multihop-client-support-and-cbit-ipv-and-ipv.html

[sebastien3]

Thanks @pman 

On ASR this command and bfd-map is OK  !

fall-over bfd multi-hop check-control-plane-failure strict-mode

 I wanted to try between the ASR and the 3750X it is not possible to use bfd-map...

[pman]

about the 3750X i found this one:

Restrictions for Bidirectional Forwarding Detection

Restrictions for BFD include:

• BFD works only for directly connected neighbors. BFD neighbors must be no more than one IP hop away. Multihop configurations are not supported.
• The switch supports up to 100 BFD sessions with a minimum hello interval of 100 ms and a multiplier of 3. The multiplier specifies the minimum number of consecutive packets that can be missed before a session is declared down.
• To enable echo mode the peer system must be configured with the no ip redirects command.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-2_1_e/configuration/guide/scg3750x/swbfd.html

[sebastien3]

OK @pman !

A cable is directly connected between R1 and 3750X...

It seems to me that I am good ! BFD not work...

################# ASR R1
interface GigabitEthernet0/2/1
 description *** TEST to 3750X  Vlan5 ***
 ip address 10.0.0.6 255.255.255.252
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 negotiation auto
 bfd interval 600 min_rx 600 multiplier 3
!
################# 3750X
interface Vlan5
 description *** TEST to R1 G0/2/1 ***
 ip address 10.0.0.5 255.255.255.252
 no ip redirects
 no ip unreachables
 no ip proxy-arp
 no ip mroute-cache
 bfd interval 600 min_rx 600 multiplier 3
!

[pman]

Hi,

please attache output of show bfd neighbors details, show bfd neighbors, and bgp config

Thanks,

[sebastien3]

R1#sh bfd neighbors details
IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
10.0.0.5                         4102/2          Up        Up        Gi0/2/1
Session state is UP and using echo function with 750 ms interval.
Session Host: Software
OurAddr: 10.0.0.6
Handle: 4
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 1000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 1000(604710)
Rx Count: 603073, Rx Interval (ms) min/max/avg: 2/1012/881 last: 224 ms ago
Tx Count: 604718, Tx Interval (ms) min/max/avg: 2/1005/879 last: 542 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: EIGRP CEF
Uptime: 6d03h
Last packet: Version: 1                  - Diagnostic: 0
             State bit: Up               - Demand bit: 0
             Poll bit: 0                 - Final bit: 0
             C bit: 0
             Multiplier: 3               - Length: 24
             My Discr.: 2                - Your Discr.: 4102
             Min tx interval: 1000000    - Min rx interval: 1000000
             Min Echo interval: 600000

3750X#sh bfd neighbors details

IPv4 Sessions
NeighAddr                              LD/RD         RH/RS     State     Int
10.0.0.6                            1/4125       Up        Up        Vl5
Session state is UP and using echo function with 600 ms interval.
Session Host: Software
OurAddr: 10.0.0.5
Handle: 1
Local Diag: 0, Demand mode: 0, Poll bit: 0
MinTxInt: 1000000, MinRxInt: 1000000, Multiplier: 3
Received MinRxInt: 1000000, Received Multiplier: 3
Holddown (hits): 0(0), Hello (hits): 1000(26)
Rx Count: 26, Rx Interval (ms) min/max/avg: 8/999/864 last: 705 ms ago
Tx Count: 28, Tx Interval (ms) min/max/avg: 8/990/806 last: 537 ms ago
Elapsed time watermarks: 0 0 (last: 0)
Registered protocols: EIGRP CEF
Uptime: 00:30:22
Last packet: Version: 1                  - Diagnostic: 0
             State bit: Up               - Demand bit: 0
             Poll bit: 0                 - Final bit: 0
             C bit: 0
             Multiplier: 3               - Length: 24
             My Discr.: 4125             - Your Discr.: 1
             Min tx interval: 1000000    - Min rx interval: 1000000
             Min Echo interval: 600000

The BGP setup is the same as my first post. I just add a new peer/ip...

I just add on R1:

bfd map ipv4 10.0.0.6/32 10.0.0.5/32 mh1
bfd-template multi-hop mh1
interval min-tx 50 min-rx 50 multiplier 3

!

neighbor 10.0.0.5 fall-over bfd multi-hop check-control-plane-failure

On 3750X : neighbor 10.0.0.6 fall-over bfd

[sebastien3]

No one has an idea ?

I have an alternative with BGP neighbor 10.0.0.5 timers 3 15