Re: ECMP Static route with BFD Issue

Greetings

this scenarios has come up again.  Reading the RFC5880 it looks like the condition maybe caused because when we put our LB into a maintanence mode we set the BFD state to AdminDown and not DOWN.  I saw on the router that when the BFD session is AdminDown the ECMP routes are still there.  In our case when in MTC mode the forwarding path is actually down. 

Does anybody have insite on how Juniper emplimented the BFD state differences and ECMP routes?

Here is the sample when the LB forwarding path is down:

labadmin@RTRL012> show bfd session address 172.18.113.136 extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
172.18.113.136           Down      irb.305        0.501     2.000        3
Client Static, TX interval 0.167, RX interval 0.167
Session down time 00:00:18, previous up time 00:00:36
Local diagnostic CtlExpire, remote diagnostic None
Remote state Up, version 1
Session type: Single hop BFD
Min async interval 0.167, min slow interval 2.000
Adaptive async TX interval 2.000, RX interval 2.000
Local min TX interval 2.000, minimum RX interval 0.167, multiplier 3
Remote min TX interval 0.167, min RX interval 0.000, multiplier 3
Local discriminator 76, remote discriminator 0
Echo mode disabled/inactive, no-absorb, no-refresh
Adaptation disabled
  Session ID: 0x1b6


labadmin@RTRL012> show route 172.18.155.129 terse table inet.0

inet.0: 1017 destinations, 1020 routes (1017 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

A V Destination        P Prf   Metric 1   Metric 2  Next hop        AS path
* ? 172.18.155.128/29  S   5                       >172.18.113.137

Thsi is the router state when the LB is in MTC Mode:

labadmin@RTRL012> show route 172.18.155.129 terse

inet.0: 1019 destinations, 1022 routes (1019 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

A V Destination        P Prf   Metric 1   Metric 2  Next hop        AS path
* ? 172.18.155.128/29  S   5                       >172.18.113.136
                                                    172.18.113.137


labadmin@RTRL012> show bfd session address 172.18.113.136 extensive
                                                  Detect   Transmit
Address                  State     Interface      Time     Interval  Multiplier
172.18.113.136           Down      irb.305        0.501     2.000        3
Client Static, TX interval 0.167, RX interval 0.167
Session down time 00:15:46, previous up time 00:03:38
Local diagnostic NbrSignal, remote diagnostic AdminDown
Remote state AdminDown, version 1
Session type: Single hop BFD
Min async interval 0.167, min slow interval 2.000
Adaptive async TX interval 2.000, RX interval 2.000
Local min TX interval 2.000, minimum RX interval 0.167, multiplier 3
Remote min TX interval 0.167, min RX interval 0.167, multiplier 3
Local discriminator 76, remote discriminator 1203799065
Echo mode disabled/inactive, no-absorb, no-refresh
Adaptation disabled
  Session ID: 0x1b6

1 sessions, 1 clients

You can see that the ECMP routes are not removed during AdminDown state.

TIA.