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.