Re: Is Fragmentation at IP layer even needed ?

On 2/8/16 10:56 AM, David Borman wrote:
> > 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 worst…
> If you wind up in a scenario where you get locked to a particular OS
> vendor because it’s the only one that supports IPv6 fragmentation
> > 1500 octets, then that is probably the least of your worries.  I’d
> be much more worried about IPv6 fragmentation in light of Ron
> Bonica’s comment that intermediary nodes drop packets with extension
> headers, which is bad news even for fragmented packets in the
> 1280-1500 range.
For those of us with ecmp load balancing the challenge of associating a
fragement with the rest of the flow are also a problem. In my own case I
can engineer circumstances where I should never receive such a fragment,
so I can safely drop them anyway but I doubt everyone has that luxury.

> -David

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