RE: Opportunistic Tunneling

["Tony Hain" <alh-ietf@tndh.net>]

Pekka Savola wrote:
> No, ISATAP is not really applicable AFAICS.  Remember that the topic
> here is "opportunistic tunneling" -- with a requirement that the
> tunneling works independent of ISPs, automatically.  ISATAP requires
> ISATAP router and set-up.

Only to get out of the routing domain. ISATAP end systems will use
opportunistic tunneling directly because ND is not required to acquire the
IPv4 (link layer) address. 

> 
> On the other hand, when your ISP wants to give you IPv6 access using
> tunneling, ISATAP could be on the table (but that was a separate
> subject).

ISATAP should never show up in the public network because it allows use of
RFC1918 addresses. 

> Economic models, to an extent, make deployments realistic (or not), so
> I personally think this is somewhat of a factor in the discussions
> whether to recommend some model for deployment.  Of course, the IETF
> cannot _force_ anyone to a model.

As Bob & Christian have said, the IETF is not in a position to recommend
economic models. Entire industries like cable ISPs will have economic
drivers (like the cost/operational complexity of whole-sale replacement of a
cable modem plant) that will make technologies like 6to4 & Teredo much more
attractive than they would be to a campus or transit ISP. Operating 6to4 or
Teredo relays as an integral part of a cable infrastructure provides a very
simple deployment path. At most the IETF might document that the IPv4 side
of such relays should be restricted to local customers, but even that is
really none of the IETF's business.

Tony