[168335] in North American Network Operators' Group
Re: Experiences with IPv6 and Routing Efficiency
daemon@ATHENA.MIT.EDU (Frank Habicht)
Tue Jan 21 05:52:40 2014
Date: Tue, 21 Jan 2014 13:52:15 +0300
From: Frank Habicht <geier@geier.ne.tz>
To: Owen DeLong <owen@delong.com>
In-Reply-To: <4C6F9F07-E4E3-4E49-9F94-3DDC48B83BBD@delong.com>
Cc: "<nanog@nanog.org>" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Hi Owen,
On 1/21/2014 12:13 PM, Owen DeLong wrote:
> On Jan 18, 2014, at 23:19 , Frank Habicht <geier@geier.ne.tz> wrote:
>> c) v6 with a few extension headers
> In this case, it will be at 40+o+n octets into the packet where o is the
> number of octets contained in headers prior to the TCP header and n is
> defined as in (b) above.
my point tried to be that it can be hard for an ASIC to know 'o'
>> now program a chip to filter based on this port number...
> I think you might want to be more specific. After all, an ARM 9 is a
> chip which can easily be programmed to do so (in fact, I can point to
> iptables/ip6tables as running code which does this on the ARM 9).
I was thinking about hardware that's forwarding packets "not in software"
some of those boxes probably want to limit tcp ports 179 and 22.
> So... I suppose that whether your complaint has merit depends entirely
> on whether or not extension headers become more common on IPv6 packets
> than options have become on IPv4 packets or not and also on how hard it
> is to build fast-path hardware that bypasses extension headers that it
> does not care about. Since you only need to parse the first two fields
^^^^ ?
> of each extension header (Next Header Type and Header Length)
... recursively for all extension headers ...
> to know
> everything you need to bypass the current header, it shouldn't be too
> hard to code that into a chip...
who's done that so far?
Up to what number of EHs or octet-length?
Thanks,
Frank
