Re: draft-nordmark-multi6-sim-00.txt

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

> I understood that the routers rewrite but the information is in the
> extension header ...

The information that is it ok to rewrite the locators is
in the IPv6 nextheader field - a designated value should be allocated
for the M6 protocol in SIM to have this semantics (in addition
to indentifying to the endnode that the this is a multihoming
packet) . The information that gets rewritten
is the IPv6 source field.

Thus there is no need to parse additional extension headers to do the
rewriting. If hop-by-hop options are used the HBH header would 
need to be looked at to see whether its nextheader value says "rewrite ok".
Presumably a routing header could also be placed before the M6 header
thus the nextheader field in the routing header would need to be inspected.

But other extension headers (destination options, ESP, AH, fragment)
are placed after the M6 header.

FWIW NOID and CB64 take the same approach except that in order to
avoid a shim M6 header in every packet the router need to
look for a nextheader value in a range of 8 values to mean "rewrite ok".

  Erik

   Erik