Description

Standalone SRX1500 running packet forwarding mode, BFD with 100ms x 3 enabled in BGP but fails to work.  Please note that BFD works well in flow mode.

Symptoms

Configure BFD as below  in Packet mode 
labroot@jtac-srx1500-r2019> show security flow status  
  Flow forwarding mode:
    Inet forwarding mode: packet based
    Inet6 forwarding mode: flow based
    MPLS forwarding mode: packet based
    ISO forwarding mode: drop
    Tap mode: disabled (default)
#BFD interval 100ms x3 which should result in Inline Distributed mode

labroot@jtac-srx1500-r2019> show configuration protocols bgp group test2    
type external;
local-address 10.10.11.1;
peer-as 300;
local-as 200;
neighbor 10.10.11.2 {
    bfd-liveness-detection {
        minimum-interval 100;
        multiplier 3;
    }
}
 
#BFD not up

labroot@jtac-srx1500-r2019> show bfd session 
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
10.10.11.2               Init      irb.11         6.000     2.000        3   
#Distributed mode enabled

labroot@jtac-srx1500-r2019> show ppm adjacencies detail 

Protocol: BFD, Hold time: 12000, IFL-index: 81
Distributed: TRUE
BFD discriminator: 20, BFD routing table index: 0
Num Packets: 57, Absorbed Packets: 0, Rx Packet: 20 80 03 18 00 00 00 11 00 00 00 14 00 1E 84 80 00 1E 84 80 00 00 00 00 
Distribution handle: 58, Distribution address: fpc0

Adjacencies: 1, Remote adjacencies: 1
 

Solution

This is by Design, Inline BFD is not supported in Packet forwarding mode despite it works in flow mode. 

Modification History

2024-06-07 : Article Created
2024-09-27: Published to Partner and customer