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Re: Is Fragmentation at IP layer even needed ?

2016-02-08 13:55:13

In message 
<AA50FF2F-8E00-4D63-944F-75C3D5A82F48(_at_)weston(_dot_)borman(_dot_)com>, 
David Borm
an writes:

On Feb 8, 2016, at 12:23 PM, Warren Kumari <warren(_at_)kumari(_dot_)net> 
wrote:
...
On Mon, Feb 8, 2016 at 9:05 AM David Borman 
<dab(_at_)weston(_dot_)borman(_dot_)com>
wrote:
...
So if you are writing an application that needs >1500 octets, use an
IPv6 implementation that supports >1500 octet fragmentation and
reassembly.

... but as an application writer (or, basically anyone else), I have no
control over the "IPv6 implementation". Even if I'm in an environment
where I do control the OS / model of all devices, and I know they support
1500 octet, it seems like a bad idea to *rely* on that. Sometime I'm
going to want to change OS / add some other device, be able to interact
with some other system. This sounds like vendor lock at its worstâ?¦

If you wind up in a scenario where you get locked to a particular OS
vendor because itâ??s the only one that supports IPv6 fragmentation >1500
octets, then that is probably the least of your worries.  Iâ??d be much
more worried about IPv6 fragmentation in light of Ron Bonicaâ??s comment
that intermediary nodes drop packets with extension headers, which is bad
news even for fragmented packets in the 1280-1500 range.

                      -David

Just about every OS supports > 1500 byte fragmentation reassembly.  4K, 8K and
greater reassembly buffers commonly exist.

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka(_at_)isc(_dot_)org