Re: WGLC for BFD Multipoint documents (last round)

"Reshad Rahman (rrahman)" <rrahman@cisco.com> Thu, 08 February 2018 03:21 UTC

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From: "Reshad Rahman (rrahman)" <rrahman@cisco.com>
To: "gregory.mirsky@ztetx.com" <gregory.mirsky@ztetx.com>, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org>
Subject: Re: WGLC for BFD Multipoint documents (last round)
Thread-Topic: WGLC for BFD Multipoint documents (last round)
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Date: Thu, 8 Feb 2018 03:21:29 +0000
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Hi Greg,

Regarding changing bfd.SilentTail on the fly, I think we should consider adding some text “… SHOULD not be modified after the MultipointTail session has been created.“. This is to prevent false failure detections as you mentioned.

Regards,
Reshad.

From: "gregory.mirsky@ztetx.com"; <gregory.mirsky@ztetx.com>;
Date: Sunday, February 4, 2018 at 8:18 PM
To: "Reshad Rahman (rrahman)" <rrahman@cisco.com>;, "rtg-bfd@ietf.org"; <rtg-bfd@ietf.org>;
Cc: "gregimirsky@gmail.com"; <gregimirsky@gmail.com>;
Subject: Re: WGLC for BFD Multipoint documents (last round)


Hi Reshad,

<have to switch my contact for a week>

You've said:

Hi Greg,



The question about whether we need a new variable wasn’t referring to MultipointClient state (I agree this is well explained). Since I mentioned “state variable” I realize the confusion…



The question was whether we need a new state variable (not for the MultipointClient state) to control the behavior explained in this paragraph, e.g the new state variable could be called bfd.TrackTails.



   If the head wishes to know the identity of the tails, it sends

   multipoint Polls as needed.  Previously known tails that don't

   respond to the Polls will be detected.



Regards,

Reshad.

I agree that an operator should have control over whether the head does tail discovery, tail monitoring. But I think that that may require whole suite of parameters and some might need coordidation for the MultipointHead with MultipointTail, e.g. when the given MultipointTail has bfd.SilentTail changed from 0 to 1 or vice versa. Would that trigger false negative on the head? I think that there's lots of open space ofr the innovation in the area of monitoring p2mp tails. I hope that someone will be interested to continue and produce more detailed specification than draft-ietf-bfd-multipoint-active-tail. For example, time interval between multicast Poll and relationship to unicast BFD control packets to tail(s).



Best regards,

Greg Mirsky



Sr. Standardization Expert
预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D Institute/Wireline Product Operation Division


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