[Mip6] Comments on draft-wakikawa-mobileip-multiplecoa-02.txt

Thierry,

I looked at draft-wakikawa-mobileip-multiplecoa-02.txt and the fundamental
architectural idea here seems to be to introduce a new namespace, the BID,
to tie together multiple CoAs to one HA. I can see a couple issues with this
approach.

1) On the one hand, the CoAs are not exposed to the transport layer on the
two hosts, so the transport layer doesn't have the opportunity to assess
such connection characteristics as congestion, reachability, bandwidth, etc.
when determining which CoA to use, or whether to use multiple
CoAs (draft-matsuoka-multilink-transport-requirement-00.txt). An
example is the MPEG streaming video example I cited in previous email. If
the transport layer has access to the multiple addresses and information on
the connection, it can decide whether to send the extra layers to improve
video quality over a high bandwidth v.s. low bandwidth connection.  Another
example is SCTP which uses multiple addresses to good advantage, switching
to a new address if unrecahability develops on the currently active one.

2) On the other hand, although the BID is halfway to being an endpoint
identifier, yet there's still the HoA to deal with. Proposals such as MAST
(draft-crocker-mast-analysis-01.txt) and HIP
(draft-moskowitz-hip-arch-05.txt) go all the way in this regard and
introduce endpoint identifiers that are independent of IP addresses and are
utilized for session identification. The endpoint identifier is visible to
the transport layer and is used for transport session identification, rather
than an IP address. They use different approaches - MAST identifiers are
session specific and negotiated while HIP identifiers are global - but the
basic architectural idea is the same.

            jak

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