Gyan Mishra <> Wed, 16 October 2019 04:10 UTC

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From: Gyan Mishra <>
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Subject: Re: PIM BFD RFC
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Date: Wed, 16 Oct 2019 00:10:25 -0400
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To: Greg Mirsky <>
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+ Mankamana and Benchon 

...from PIM WG & BESS which owns LSM MVPN mLDP / P2MP TE S-PMSI and MI-PMSI.

We were discussing PIM BFD use case on this BFD WG thread  and  RFC 8562 and RFC 8563 covers strictly L3 VPN LSM ( label switched Multicast) LMDT (labeled multicast distribution tree) mLDP / P2MP p-tree S-PMSI ( selective constrained MDT / Cisco data MDT) MI-PMSI(inclusive MDT for all VRFs) and not Ethernet switching LAN based PIM SM BFD.

We have a new draft in the PIM WG PIM DRLB load balancing GDR capability and the draft of hashing of ASM PIM RP hash and ASM and SSM S,G hash load balancing of traffic across both PIM DR/BDR does significantly help with convergence as 50/50 LB split but during failover you still have 50% of the traffic that still has to reconverge and SPT tree MRIB/MFIB state has to rebuild.

So the BFD PIM Draft would register the PIM protocol and in asynchronous mode with echo disabled we can achieve sub millisecond detection time and convergence during failover.

So I do think we need a PIM BFD Draft. 

Since this falls between multiple WG but since BFD related this would be under the BFD WG.

I am part of the BFD WG as well as part of PIM and BESS so I can assist in writing the draft if we are all in agreement that this is needed and can work with Mankamana and Benchon as well in creating the draft.


Sent from my iPhone

> On Oct 12, 2019, at 12:07 AM, Greg Mirsky <> wrote:
> Hi Gyan,
> thank you for your interest in this draft. We've described how RFC 8562 BFD for Multipoint Networks can be used to shorten convergence in PIM-SM. The similar scenario discussed in draft-ietf-bess-mvpn-fast-failover where p2mp BFD is used by tails to detect the failure of the head/root or the multicast tree. If it is required for the head/root to detect a defect of the multicast tree toward a tail, we'll turn to RFC 8563 BFD for Multipoint  Active Tails as in draft-hu-bier-bfd.
> Hope this information would be helpful to you. I always welcome your questions.
> Regards,
> Greg
>> On Fri, Oct 11, 2019 at 7:40 PM Gyan Mishra <> wrote:
>> Greg 
>> I saw your draft on PIM BFD use cases but could not find the RFC on PIM BFD.
>> Thanks 
>> Gyan
>> Verizon Communications 
>> Cell-301 502-1347
>> Sent from my iPhone
>>> On Oct 11, 2019, at 9:53 PM, Gyan Mishra <> wrote:
>>> BFD WG
>>> Anyone know what the RFC or draft for PIM BFD support.
>>> Thank you
>>> Gyan 
>>> Verizon Communications 
>>> Sent from my iPhone