On 07/14/10 12:51 AM, Mathilde Durvy (mdurvy) wrote:
Hi Carsten,
Hence, it seems to me that we should recommend that routers do not use
these features between them.
As a minimum, a router node entering a 6LoWPAN needs to learn about the
compression context in use in this 6LoWPAN.
Unless the routing protocol is configured to strictly stay within the
6LoWPAN, I have no idea how to do this in a routing protocol.
[Mathilde] Well distributing context is an optional feature of 6lowpan-ND. I
was trying mainly to clarify the registration part. In addition, it seems
possible to work that out with current routing protocols for LLN. If it was
not the case, the RS/RA could be used to learn network parameters only. This
generates quite some overhead traffic but it might be the only solution.
6lowpan-nd allows for different routing protocols.
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.
But if for instance the routing protocol doesn't carry the MAC
addresses, then you can use the registration mechanism between the routers.
[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] 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)
I don't understand why one would ever want to use multicast NS in the LLNs.
- In networks where DAD is needed, we might need to decouple DAD from
registration as specified today
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).
Erik
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