On 20/10/2016 15:01, Michael Richardson wrote:
>
> Brian E Carpenter <brian.e.carpen...@gmail.com> wrote:
> > As I said, I don't really see the issue there. According to
> > https://tools.ietf.org/html/draft-ietf-anima-grasp-07#section-3.6 the
> > negotiation (or synchronization) session has its own session-id,
> > distinct from the one used for discovery, even if they did re-use the
> > same TCP session. Messages for the two transactions (discovery and
> > negotiation) could be demultiplexed using the session-id, even if they
> > overlapped in time for some reason. The ids will never clash, because
> > the same party initiates discovery and negotiation.
>
> But, can't there be multiple back and forths of M_NEGOTIATE?
> As such the same session-id would be sent in an M_NEGOTIATE in both
> directions.
Exactly. Like my example that I sent. Manually prettified, it reads:
A to B: [M_REQ_NEG, 8280376, ['EX3', 1, 6, ['NZD', 156]]]
B to A: [M_NEGOTIATE, 8280376, ['EX3', 1, 6, ['NZD', 155.5]]]
A to B: [M_END, 8280376, [O_ACCEPT]]
What's the problem? 8280376 is unique in A, and {8280376, A's address}
is unique in B. They can't get confused, even if there are numerous
negotiation steps.
OK, so now I'll make one with multiple steps [pause while I run my
example generator and prettify the results]
A to B: [M_REQ_NEG, 11146801, ['EX2', 1, 6, ['NZD', 393]]]
B to A: [M_NEGOTIATE, 11146801, ['EX2', 1, 6, ['NZD', 56.0]]]
A to B: [M_NEGOTIATE, 11146801, ['EX2', 1, 6, 294.75]]
B to A: [M_WAIT, 11146801, 20899]
B to A: [M_NEGOTIATE, 11146801, ['EX2', 1, 6, ['NZD', 84.0]]]
A to B: [M_NEGOTIATE, 11146801, ['EX2', 1, 6, 235.8]]
B to A: [M_END, 11146801, [O_DECLINE, 'Insufficient funds']]
I use random numbers to generate the test cases. That was a nice one, it
shows B telling A to wait and it shows a failed negotiation. But since
A and B both know who they are, the fact that the session-id is identical
isn't a problem.
Brian
> If not, then I don't understand negotiation at all.
>
>
> --
> Michael Richardson <mcr+i...@sandelman.ca>, Sandelman Software Works
> -= IPv6 IoT consulting =-
>
>
>
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