[bess] [BESS] Discussions about DF-election FSM.

[<[e-mail]>]

Hi Jorge,







I read the draft-ietf-bess-evpn-df-election-framework-08 and find it seemed not clear in the DF election FSM .  


I didn't find clear explanation about when to advertise the ES route(RT-4) according to the FSM.



I think it is the DF_TIMER (not ES_UP) event that triggers the advertising of ES route.


Because if not the remote PEs will re-elect a new DF immediately after the advertisment, and the new DF may be the PE in DF_WAIT state itself. 


but I didn't find clear explanation in the relevant event transmissions.






The description in draft-ietf-bess-evpn-df-election-framework-08 section 3.1 as follows:





   2.  INIT on ES_UP: transition to DF_WAIT.

   ... ...

   6.  DF_WAIT on DF_TIMER: transition to DF_CALC.

   7.  DF_CALC on entering or re-entering the state: (i) rebuild


       candidate list, hash and perform election (ii) Afterwards FSM

       generates CALCULATED event against itself.






And I find in RFC7432 Section 8.5 that the advertising of ES route is not influenced by the DF_TIMER.






   1. When a PE discovers the ESI of the attached Ethernet segment, it     

      advertises an Ethernet Segment route with the associated ES-Import

      extended community attribute.




   2. The PE then starts a timer (default value = 3 seconds) to allow       

      the reception of Ethernet Segment routes from other PE nodes

      connected to the same Ethernet segment.  This timer value should

      be the same across all PEs connected to the same Ethernet segment.






So I think there is an update of RFC7432 and it needs to be clear described in the draft.


or the DF timer in RFC7432 is not the same with the DF timer in that draft?






Is my understanding right?






Best Regards


Bob