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

[Jeffrey Haas <[e-mail]>]

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.

-- Jeff