Re: Question about draft-nordmark-multi6-noid-01.txt

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

> I've just read NOID draft (may be I've read it too fast ) and
> I haven't found anywhere how to re-write the source 
> address.  If the packet doesn't have any extra
> option/extension header to carry the additional prefix(es),
> how can the router make this rewriting ?

The border router checks whether rewriting is allowed by looking at the nexthdr
field in the IPv6 header. If it is between P1 and P1+7 (a to be defined range
of "protocol values") then rewriting is ok.

The source address field is then modified to have high-order bits
(high-order 48 bits in many cases) which corresponds to the exit
the border router is using. For instance, if it is sending a packet
to an ISP who was delegated prefix 2000:1:2::/48 then
it will place that value in the top 48 bits of the source address.

Thus the router doesn't need to have a list of prefixes to choose between
as part of the packet.

  Erik