On 10/9/11 3:38 PM, Ole Troan wrote:
Erik, et al,
to expand on the ideas I presented on MLSR (or rather MLSRv2 as it hasn't really
been described anywhere) as a method for numbering a routed home. please let me be
clear that I'm not convinced this is a good idea. i.e. why not just get< /64?
I do think we could get something working though.
routers can be in an arbitrary topology. all routers running a routing protocol.
the site prefix (/64) is either advertised in the IGP with a new LSA or
proxying of RA messages is done (split horizon).
a router advertises the same /64 prefix (in a PIO) on all of its interfaces. L
bit is 0.
the link model here is that all hosts are off link from each other. link-local
scope is restricted to only the physical link. multicast link-local scope as
well.
And I assume the routers would pass around /128 routes for the hosts in
the home, and would automatically inject such a route when the
SAVI-style table learns about a new address.
Are those assumptions correct?
a host uses SLAAC (or DHCP) to create an address, then does DAD as normal. the
first hop router uses it's routing topology database
to check for conflicts. similar mechanisms described in SAVI are used to glean
address information from the host. the SAVI binding
database is then used to inject host routes into the IGP.
What happens when the router crashes - does it loose its SAVI-style
table? Does it keep it in stable storage?
If it looses it, then nobody would know on what link the hosts are,
since the hosts aren't required to periodically send any announcement to
the routers.
What happens when a packet arrives for an IP address that is in the /64
prefix for the home, but there is no /128 route for it? Flood
everywhere? Drop?
We looked that this when we worked on 6lowpan-nd, and concluded that by
doing explicit registrations from hosts to routers (the Address
Registration Option) with a lifetime we can make such networks work well
without requiring stable storage.
But that implies a host change.
Erik
this requires no flooding of ND, or any other changes to on-link protocols for
loop detection. no changes in hosts either.
only downside is that it requires a host to have sent a packet of some form for
the SAVI binding to be initiated.
it might also be possible to support host mobility with the home with this
mechanism.
cheers,
Ole
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