Re: [Idr] Benjamin Kaduk's Discuss on draft-ietf-idr-flow-spec-v6-19: (with DISCUSS and COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Mon, 16 November 2020 07:58 UTC

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Date: Sun, 15 Nov 2020 23:57:56 -0800
From: Benjamin Kaduk <kaduk@mit.edu>
To: Jeffrey Haas <jhaas@pfrc.org>
Cc: Christoph Loibl <c@tix.at>, "idr@ietf. org" <idr@ietf.org>, draft-ietf-idr-flow-spec-v6@ietf.org, Robert Raszuk <robert@raszuk.net>, idr-chairs@ietf.org, The IESG <iesg@ietf.org>, Erik Kline <ek.ietf@gmail.com>
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Subject: Re: [Idr] Benjamin Kaduk's Discuss on draft-ietf-idr-flow-spec-v6-19: (with DISCUSS and COMMENT)
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On Mon, Nov 16, 2020 at 03:09:01AM -0500, Jeffrey Haas wrote:
> Ben,
> 
> On Mon, Nov 09, 2020 at 12:58:05PM -0800, Benjamin Kaduk wrote:
> > > How can we continue?
> > 
> > I think it would be okay to just drop the specific mention of 1- and 2-byte
> > encoding for the flow label match, so we have "[t]ype 13 component values
> > SHOULD be encoded as 4-byte quantities (len=10)".
> 
> I will note that Juniper's implementation simply goes for best-fit for any
> given value.  While the SHOULD for 4-byte sizing won't make us
> non-conformant, it's not what we do.  E.g. a value that can fit into one
> byte will use that length.
> 
> Given the general encoding of lengths in the base flowspec document, you can
> insist on whatever size you want for the SHOULD of the size to send, but
> receivers need to follow Postel's maxim on receipt.

I agree.

Thanks for commenting,

Ben