Re: [v6ops] new draft: draft-taylor-v6ops-fragdrop

[Joe Touch <[e-mail]>]

On 10/31/2012 10:54 AM, Fernando Gont wrote:
> On 10/31/2012 03:27 PM, Brian E Carpenter wrote:
>>> But why? If you can't get extension headers to work reliably in the
>>> Internet (as opposed to in your own network), then what's the point? You
>>> still need a fallback plan for when they get dropped, and users don't like
>>> waiting. Why not just use the more reliable plan all the time?
>>
>> For MTU/fragmentation issues, there may be such a plan.
>>
>> There are other extension headers for which there is no such plan.
>
> The end-result is/is going to be that sine extension headers are not
> reliable, no mechanism will be able to rely on them. SO, in practice,
> you better put your "options"/fragmentation somewhere else, or prepare
> to be dropped.
>
> It happened with IPv4 options already....

Yes, but the whole point of the IPv6 option architecture was to avoid 
the issues seen with IPv4 options.

Consider that:

	- routers don't like fragments because they can't inspect them

	- so we tunnel and fragment in a higher level protocol

		the router now needs to implement the higher protocol
		and still fragment or else we cannot have tunnels

		the routers on the path still cannot inspect the
		higher-level fragments

So we're back to the reason this all breaks - routers doing something 
that we simply cannot support in the architecture.

Joe