Re: [Fwd: Re: [RRG] Re: [RAM] Tunneling overheads and fragmentation]

[RÃmi Denis-Courmont <rdenis at simphalempin.com>]

Le Tuesday 18 September 2007 23:43:30 Templin, Fred L, vous avez ÃcritÂ:
> Brian,
>
> After having discussed with others, please see attached
> for a proposal that addresses the MTU issues for tunnels.
> It also addresses the multi-mtu subnet issue, since it
> does not rely on ICMP "packet too big" messages from the
> last-hop router.

From a purely cosmetic standpoint, I think MRU (Max Receive Unit) is a lot 
more readable that EMTU_R.

From a technical perspective, this strikes me as:
- It requires knowledge of informations that is often hidden/not provided to 
the tunneling implementation, including path MTU and IP ID. That makes it 
possibly unimplementable without strong integration/dependency between the 
tunneling and the outer IPv4 stacks.

- It requires maintaining quite a bit of extra state per neighbor. I have 
received complaints that Teredo relays are having scalability issues already 
now due to the growing numbers of clients, and adding more per-client state 
would make matters worse.


-- 
RÃmi Denis-Courmont
http://www.remlab.net/

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