Comments on draft-coene-sctp-multihome-03.txt

[Erik Nordmark <Erik.Nordmark@sun.com>]

The document says:
    Under the assumption that every IP address will have a different,
    seperate path towards the remote endpoint, (this is the
    responsibility of the routing protocols or of manual configuration)
    , if the transport to one of the IP addresses (= 1 particular path)
    fails then the traffic can migrate to the other remaining IP address
    (= other paths) within the SCTP association.

The assumption or requirement that the routing protocol explicitly make
packets destined to different IP addresses use independent paths doesn't
match what actual IP routing protocols do.
So I think either the assumption is seriously out of whack with reality,
or there is a need to rephrase this along the lines of:
Packets to different IP addresses, in particular when sent out different
interfaces on the sender, might travel on independent paths through the
network. However, ensuring this probably requires manual static routes
and not a dynamic routing protocol. If this path independence exists
it is possible to take advantage of it in SCTP by having traffic migrate
to use a different IP address after a failure.

    As a practical matter, it is recommended that IP addresses in a
    multihomed endpoint be assigned IP endpoints from different TLA's to
    ensure against network failure.

TLAs?? What are those?

  Erik