Re: Transport level multihoming

[RJ Atkinson <rja@inet.org>]

At 11:21 03/04/01, Greg Maxwell wrote:

>Has anyone here had any discussion about the potential for transport level
>multihoming (like in SCTP, RFC2960) to replace the current practice 
>globally advertised multihoming on the IPv6 Internet?

        SCTP is interesting, but not sufficient.  The current
multihoming practice works with existing TCP-based and UDP-based 
applications, without changing them.  Changing the installed
base of those applications to use SCTP instead isn't feasible
in any sort of interesting timeframe -- if such migration is
feasible at all.

>If the transport pushes multihoming to the end node and IP layer
>multihoming not being propagated beyond direct peers, it would seem that
>such a system could significantly further the scalability of the Internet,
>while increasing the level of flexibility of multihoming (i.e. if the
>transport allows adding address to a connection in progress, this would
>facilitate mobility, and other benifits).
>
>Has a potential policy of 'No global IP multihoming of short prefixes;
>Leave multihoming to the end nodes' for IPv6 been discussed here? 

        One might consider the use of techniques such as GSE
(or EIDs or Stack Names) to separate the host's identity
from its routing goop.  Such an approach would require at least
changing the way UDP/TCP checksums are calculated (new 
pseudo-header) and probably requires enhancements to some
directory system (DNS, LDAP, or something else).  Absent an
engineering spec for a concrete proposal, this approach is
unlikely to go anyplace.

IMHO,

Ran
rja@inet.org