[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Thoughts about layering multi-addressing



On the other hand I'm not sure if you classification above
is exact. Primary locators are used in SCTP, but do
we need them in shim? Or did you mean "one current locator"?

I don't understand the difference.

Also, some extensions in the interface appear unavoidable,
like telling transport that it needs a slow start, or the ability
of multihoming aware transports and applications to bypass
the shim if they want to.

Agreed wrt sending events to the transports.

I am not so sure about the usefulness of a generic bypass mechanism. Diagnostic applications will require such bypass, for sure, and it will probably be a useful mechanism during a transition period, e.g., for SCTP.

However, from an architectural point of view I think that the shim layer is exactly the right layer to share information about the available IP addresses. The set of addresses is a property of the host, and therefore seems to belong to the upper part of the IP layer. The more specific properties of a path (an address pair), like QoS and what protocols/ports are available, seem to belong to a upper layer, though. Hence, from this point of view IMHO the shim should take care of distributing information about the addresses that belong to the same host while, in general, path discovery functions belong to the upper layers.

This was reflected also in the other mail with the "stepped" protocol model, where there is an additional layer between the "basic shim" and the unmodified ULs.

--Pekka