Hello,
During the last IETF, there was a discussion about when a mobile node
should use its care-of address for communications. One possible answer
is "never". Mobile IPv6 was designed to avoid extra signaling overhead
that might result from the use of the home address. However, if the
mobile node can make the following assertions:
1. No mobility events will occur
2. The other endpoint does not need the mobile node's DNS name
3. The other endpoint is not concerned with the mobile node's
home address
or, alternatively, if (3), and the mobile node does not expect to
receive any packets from the other endpoint, then it is likely to
be safe for the mobile node to use its care-of address. These
considerations, by the way, are the same as for IPv4. Another
interesting factor is what might be meant by (1). If the layer-2
protocols handle local mobility over a wide enough range, then
there is a corresponding relaxation on how rarely the conditions
might be satisfied.
I claim that it is up to the application to make these determinations,
or else it is up to the context in which the user invokes the
applications. Sometimes the same application may, or may not, have
requirements for smooth network connectivity in the face of mobility
events. Anything that is considered a "session" is an example of
something that is likely to fail to satisfy the abovementioned
conditions.
During the IPng meeting, there was a proposal to create a mailing
list for discussion of these issues. If the mailing list is already
in operation, I'd like to join up. I hope this message will be
considered relevant.
This whole problem is merely a particular example of a much larger
issue regarding the association of application invocation context
and IP addressability. For instance, if a user wishes to associate
various "identities" to various IP addresses, then the user might
try to get applications to select IP source addresses that appropriately
express the desired identity to the other endpoint of the application's
communication. From this point, we "could" devolve into more extended
discussion about the dual role of the IP(v6) address as a way to
encode both an identity and a route. I do not propose to regurgitate
that entire discussion again, but I do note that it is highly relevant.
Instead, I would like to point out that in particular the use of
anonymous IPv6 addresses has to be considered as something under
the control of the application invoked by the user. Thus, it is not
realistically possible to specify default source selection rules for
the use of anonymized IPv6 addresses. Sometimes a user wishes to
be anonymous, and sometimes a user does NOT wish to be anonymous.
I do not think it is appropriate for the network protocol stack to
try to second-guess the user's intentions.
This note is already too long, but there is much more to say.
I look forward to seeing whether others are as interested in these
issues.
Regards,
Charlie P.
--------------------------------------------------------------------
IETF IPng Working Group Mailing List
IPng Home Page: http://playground.sun.com/ipng
FTP archive: ftp://playground.sun.com/pub/ipng
Direct all administrative requests to [EMAIL PROTECTED]
--------------------------------------------------------------------
