RE: I-D ACTION:draft-huitema-v6ops-teredo-00.txt

["Christian Huitema" <huitema@windows.microsoft.com>]

> In the new draft, I see the addition of a new section entitled:
> "IAB considerations". Other than that, have there been any
> substantive changes since the previous draft version? (In
> the future, a changelog would be helpful).

There are two substantial changes: documenting the IPv4 multicast
address used in the local connectivity procedure; and documenting some
changes in the local connectivity procedures.

The change in local connectivity procedure is to require a unicast
bubble as well as a multicast one. The old write up was: if a host
receives a multicast bubble from another host, then it can send Teredo
packets to the local address. This fails in the "stacked NAT" scenario,
e.g. when the local network includes a wireless access point that is
also a NAT. (These types of NAT do not decrement the TTL value in IP
packets, so multicast works...) It fails because the multicast packet
does not refresh the NAT mapping often enough. So, in the new procedure,
the hosts send multicast bubbles to discover each other, but they also
send unicast bubbles to confirm connectivity when needed.

-- Christian Huitema