Re: [Tsv-art] ECMP [Tsvart last call review of draft-ietf-opsec-ipv6-eh-filtering-06]

Stewart Bryant <stewart.bryant@gmail.com> Thu, 06 December 2018 11:25 UTC

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To: Brian E Carpenter <brian.e.carpenter@gmail.com>, Ole Troan <otroan@employees.org>, Gert Doering <gert@space.net>
Cc: tsv-art <tsv-art@ietf.org>, OPSEC <opsec@ietf.org>, IETF-Discussion Discussion <ietf@ietf.org>, draft-ietf-opsec-ipv6-eh-filtering.all@ietf.org
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From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Thu, 06 Dec 2018 11:25:15 +0000
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Subject: Re: [Tsv-art] ECMP [Tsvart last call review of draft-ietf-opsec-ipv6-eh-filtering-06]
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On 06/12/2018 00:34, Brian E Carpenter wrote:
>
>> Of course here it is only looking for two values
>> (TCP or UDP).
> You too just killed SCTP ;-)

Well the last time I heard about SCTP was when we were forced to include 
it as an option for IPFIX.

How much SCTP exists in the real world?

>
>> If it has to look at any it has a much more complex set of tests, or a
>> large vector table  given the way the EH space is fragmented.
> Frankly doing it without a network processor seems wrong. You can't expect
> an ASIC or FPGA based device to handle the EH structures.
Something that has served the IETF well over the years is not to 
constrain the forwarding
implementation, and I think we would be wise to continue in that mould. 
Also we need
to remember that an NP is an application specific processor, and thus 
has various
hardware assists.

No one talks about the internals of an NP, and I am not current on any 
vendor's design,
but it is reasonable to suggest that in addition to the s/w parser there 
might
be a h/w parser that does the heavy lifting, i.e. if IPv6 packet of 
expected type, dec
TTL and do what the TCAM say picking this ECMP option else parse it the 
hard way.

Then there is something that we do not talk at all about in such 
designs: electrical power.
There is no question that it takes more power to s/w parse a packet, and 
sooner of later
the power burn of the Internet is going to come under scrutiny, and we 
will be asked
to reduce its carbon footprint.

- Stewart

- Stewart