Hi Eric, Please see my questions / comments below:
[Eric] If your favorite routing protocol ensures that the routers learn both
the IPv6 and MAC addresses of their peers, and you don't use short
addresses for the routers, then there wouldn't be any need for the
routers to register with each other.
[Mathilde] Agree
[Eric] But if for instance the routing protocol doesn't carry the MAC
addresses, then you can use the registration mechanism between the routers.
[Mathilde] This is where I don't understand how it would work. Imagine you
have a router with several routes. Let say to keep it simple a default route
and two other routes, each of these routes using a different next hop (R1,
R2, R3).
R1
|
R2 -- R -- R3
The router would then need to register with the 3 different next hops?
Wouldn't it lead to one registration per neighbor cache entry? If yes, it
seems R should decide who to register with based on the routing messages and
not based on RA received. Then, when a routing next hop changes what would
happen to the registration?
Would R1, R2, R3 all perform multi-hop DAD for R address?
[Eric] [And my head hurts too much to think about how a network with routers
using short addresses bootstrap when those addresses can be duplicates.
Thus I don't know what is the best approach for that case.]
[Mathilde] Use only EUI-64 or DHCPv6 short addresses :-)
> [Mathilde] This is not my line of reasoning at all, rather I'm trying to
> understand if the registration concept makes sense between routers. If
not,
> this means that:
> - We might need to endure the cost of an initial multicast NS for address
> resolution (unless the routing protocol messages carry SLLAO)
[Eric] I don't understand why one would ever want to use multicast NS in the
LLNs.
[Mathilde] Well, if there is no better alternative. Note that between
routers we don't have the sleeping problem and in route-over multicast NS is
not so resource consuming.
> - In networks where DAD is needed, we might need to decouple DAD from
> registration as specified today
[Eric] That would imply changing the host to router protocol, and I think
that
is the key piece we want to nail down (while allowing different routing
protocols to be used in different networks).
[Mathilde] Well, I guess I just need to be convinced the current model works
for routers as well (see my questions on registration)
Best,
Mathilde
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