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Re: Death by extension header (was:RE: New Version Notification for draft-li-6man-hbh-fwd-hdr-00.txt)

Philip Homburg <pch-ipv6-ietf-6@u-1.phicoh.com> Wed, 15 July 2020 09:33 UTC

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To: ipv6@ietf.org
Subject: Re: Death by extension header (was:RE: New Version Notification for draft-li-6man-hbh-fwd-hdr-00.txt)
From: Philip Homburg <pch-ipv6-ietf-6@u-1.phicoh.com>
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Date: Wed, 15 Jul 2020 11:33:08 +0200
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>I am watching this thread and have one question ... how any draft can
>mandate to any implementation how it should process a packet ?
>
>One implementation can use 100% programmable hardware, the other can not.
>Some process all packets in CPUs. Some may offload some processing to on
>line card CPU vs punting it to RE/RP.
>
>Some may punt only first packet and then install forwarding state in the
>dataplane so any subsequent packets are fully hardware switched.
>
>I am really not sure what is the value of this thread ....

Maybe it is not so much about implementation details but about
externally observable effects.

If adding a particular type of extension header makes throughput go down by
90% then starting to use that extension header on a large scale may become
a problem.

If the first packet with a particular destination is slow then using lots of
IPv6 addresses (for example one per process on a host) may overload a router,
etc.

So 'fast path' could be specified as within x% of the throughput/delay of a
packet without the extension header.

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