Re: [multipathtcp] 6824bis -11 review

[Rahul Arvind Jadhav <[e-mail]>]

c) sending a new ADD_ADDR with same ID + address and different port is fine
[RJ] again this is what the text already says, but I’m not still clear about this. Why ID + address has to match? Only ID should be enough.

Consider:

a) ADD_ADDR comes in saying ID=2, addr=10.0.0.1 (private)
b) MP_JOIN comes in saying ID=2, addr=8.9.10.11 (public)
c) ADD_ADDR comes in saying ID=2, addr=192.168.0.1

What does this mean? Is (c) an implicit REMOVE+ADD? And thus does this mean the subflow created in (b) is now no longer valid?

By keeping the address / ID mapping, if an address is lost, then so is the subflow.

[RJ2] Rather than viewing ( c) as an implicit REMOVE+ADD, can we see it as an UPDATE? Because ID remains same. Subflow created in (b) remains valid (not sure if I’m missing anything here, I see no reason to lose this subflow).
In step ( c), the receiver can override Address field in context to ID=2 to the new addr (192.168.0.1) ……   8.9.10.11 is kept separately as the learnt actual rcvd IP (from MP_JOIN) in the same context ID=2. We have to agree that an implementation needs to maintain this IP separately in context to ID=2 anyways.
So if we do an explicit REMOVE+ADD, the end result is the same as this UPDATE (but with much less overhead & impl ease).