Re: transmech substantial comments

[itojun@itojun.org (Jun-ichiro itojun Hagino)]

> >  4) We specify the that the ToS byte for the v4 header is 0 unless otherwise
> > specified, and refer to a couple of documents for that.  A problem with this
> > is that I'm not sure if those documents actually tackle the problem of
> > *different* protocol-version tunnels -- rather, they (AFAIR) discuss the
> > issues of ToS byte in v4-over-v4, where mapping (or not mapping) the ToS
> > byte from the inner IP header is a trivial excercise.
> > 
> > I fear that we may have to specify the rules for setting the ToS byte
> > ourselves, or at least give more guidance on that.
> 
> I don't see why we'd need to do that. Tunnels, using the same versions or
> different versions, can cross a region where the DSCP is interpreted
> differently thus the issues whether to copy the DSCP when encapsulating is
> identical AFAIK.
> 
> For the congestion bits the same considerations apply whether the IP versions
> are the same or different.
> 
> So do you have a concrete argument that we need explicit text on this?
> (If we want this to move to DS sooner rather than later I think we should
> avoid this.)

	draft-ietf-ipsec-ecn-02.txt (expired) talks about the very issue.
	it is titled as IPsec-related document, but the consideration applies
	to any kind of tunnel.

itojun