It's clear that pure endpoint-based multipathing, a la Shim6 REAP,
cannot scale.
Would you please be more specific. It is not at all clear to me.
AFAIK, SCTP is doing essentially the same thing. (I can see the
signalling load there, causing potential packet storms; is that the
"scalability" problem you are referring to?)
Putting path failure detection and recovery in ITRs instead of in
the endpoints can greatly reduce the number of messages flying
around, but a simple approach there doesn't scale either, and
without information they don't have much choice.
AFAICS, the fundamental problem here is that the network today (BGP)
cannot detect failures at the desired speed, leading to the situation
where the hosts (or your funnel points) need to overcome the deficiency.
8) When RLOC-EID is done properly (e.g., like HIP where each
concept appears on a different layer of the protocol stack), there
is no liveness problem (nor can there be one).
I don't see it. HIP properly removes dependency on location-based
names from identification functions, but it does nothing to solve
the multipath problem. You still need to find viable paths,
ascertain that multiple locators refer to the same entity (difficult
when one or both are moving -- rendezvous servers may be required,
tsk), detect path failure and switch to another one.
I mostly agree. In the HIP WG, years ago the decision was to leave
the problem of path failure detection to the SHIM6 WG, with the
intention to integrate REAP to HIP. However, with HIP (even LHIP)
verifying that the locators refer to the same entity is relatively
easy, as long as at least one of the parties retains at least one
stable locator. Rendezvous servers are a nice way to introduce stable
locator to an otherwise dynamic system... And then, under those
assumptions, finding paths and switching over is relatively easy.
Works very well in practise. We've multiple times tested it with both
proxies and individual hosts, using 2-3 different radio interfaces at
each mobile host/proxy, and moving at typical vehicle speeds in
difficult terrain. But I digress.
--Pekka
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