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Re: Correcting BFD Echo model

Jeffrey Haas <jhaas@pfrc.org> Fri, 24 March 2017 19:29 UTC

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Subject: Re: Correcting BFD Echo model
From: Jeffrey Haas <jhaas@pfrc.org>
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Date: Fri, 24 Mar 2017 15:28:58 -0400
Cc: "Carlos Pignataro (cpignata)" <cpignata@cisco.com>, Reshad Rahman <rrahman@cisco.com>, "rtg-bfd@ietf. org" <rtg-bfd@ietf.org>, "draft-ietf-bfd-yang@ietf.org" <draft-ietf-bfd-yang@ietf.org>
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To: Greg Mirsky <gregimirsky@gmail.com>
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> On Mar 24, 2017, at 3:09 PM, Greg Mirsky <gregimirsky@gmail.com> wrote:
> 
> Hi Carlos,
> indeed, the RFC 5880 does explain that the rate of BFD control packets transmitted in Async mode may be reduced when Echo is activated. If anyone is familiar with such implementation, I'd be glad to learn and discuss how this mechanism affects the data model. Regrettably, I don't have personal experience with using or implementing such mechanism.

My *suspicion* is that the configuration would represent a set of parameters for both async mode and echo mode.  These will not alter themselves automatically.

The operational mode might reflect timers that have backed off.  However, this is also true if an implementation does various forms of session auto-tuning.  An example I'm aware of is a decrease in timer aggressiveness as part of a high availability switchover event.

-- Jeff

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