Re: ISATAP in unmanaged networks?

[Pekka Savola <pekkas@netcore.fi>]

I removed ipv6@ietf.org from Cc: to avoid unnecessary cross-posting.

On Thu, 13 Nov 2003, Fred Templin wrote:
> I have not studied this space, but it occurs to me that ISATAP
> could be tried as a first alternative to check whether the two
> hosts are separated by a NAT. If there is no intervening NAT,
> it seems to me that ISATAP would provide the benefit of not
> needing the UDP header and "bubble" packets, yielding
> greater efficiency. Otherwise, if blocked by a NAT the
> initiating host coud after a short timeout try again with
> Teredo.

There are multiple cases to consider:

 - host/router is not behind a NAT:
   * the ISP is providing the ISATAP service
    ==> this is a cornercase of tunnel service by the ISP

 - host/router is behind a NAT:
   * .. when the ISP is doing the NAT (e.g., GPRS -kind of scenario, also 
sometimes used for commmon xDSL networks)
    ==> same as above, the service provided by the ISP

I don't think there's really applicability for ISATAP in this space if the 
ISP is co-operating (which is the requirement for ISATAP anyway).  
Configured tunneling (+ enhancements) is simpler and more generic.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings