Re: transmech MTU comments

>On Wed, 12 Nov 2003, Fred Templin wrote:
>> My understanding of RFC 3168 is that when the tunnel interface
>> forwards an IPv6 packet to an IPv4 interface with an ECT(0) or ECT(1)
>> codepoint in the traffic class field, it MAY set the codepoint to CE if
>> congestion is experienced. I interpret the MAY to mean that the other
>> option is to drop the packet. If the packet is to be dropped, should it
>> be dropped silently? Also, could a link restriction be considered as
>> congestion? If so, does drop silent also entail NOT sending an
>> ICMPv6 "packet too big" message back to the source?
>
> Where in the spec do you read that the MAY? What I basically read is
> 9.1.1, first paragraph, a couple of the last sentences.

Check section 5, second to last paragraph.

> But that applies to the decapsulating router only.

I don't think so. The processing entity inside the encapsulator

accepts a packet from the overlying IPv6 interface and enqueues

it to an underlying IPv6-in-IPv4 interface, so I would call that entity

a "router"

> RFC3168 doesn't seem to define how to drop the packet, by the way, so I
> assume by "dropping" they mean a silent discard.

OK.

> I'm not sure whether it makes sense to delve into ECN details in the
> spec..

Well, it seems it should be documented somewhere.

What do you suggest?