Re: [grobj] Referral definition and its purpose?

Sorry to jump in discussion.

On Thu, May 27, 2010 at 12:49 PM, Keith Moore <moore@network-heretics.com>wrote:

>  On 5/27/10 12:31 AM, Dan Wing wrote:
>
> 	The definition of referral should be tightened up slightly
> 	that the parties are exchanging the information via one
> 	channel (e.g., SIP signaling) but want to communicate (as)
> 	directly (as possible) with each other *not* using that
> 	channel.
>
> that's certainly one case.  another case is when parties A
> and B exchange information about how either A or B can
> contact one or more other parties.
>
>
> Two party case is easier to understand and conceptualize.
> This covers a *huge* number of important cases.
>
> agree.
>
> Then, in a later section number of the same document, we
> can explain 3 party case.
>
> I think I'd rather have the various examples together in the document, but
> I won't try to nail down the document outline just yet.
>
>  also, the referred-to path doesn't have to be more direct
> than the path over which the referral is taking place.
>
>
> Sure.
>
> But my point is that it is a *different* path than the
> signaling path.   I agree the path could be longer and
> could go around the moon - twice.
>
> it's _probably_ a different path because if it were the same path, there'd
> be little need for the referral.  just reuse the same source address,
> destination address, destination port as seen by the initiator of the
> connection (though that might not work if the new connection needed to be
> initiated by the receiver of the original connection).
>
> but to be general, it shouldn't _have_ to be a different path.  it should
> be possible to use a referral that specifies the same path used by the
> connection used to send the referral.   (or to put it another way, do you
> really want the API to say "sorry, you can't use this referral because you
> received it over the very path that it specifies?")
>
> here's an example: over path P1, A sends to B a referral that specifies
> three paths by which A can be reached: P1, P2, and P3.  when B tries to
> reconnect to A, its circumstances are such that P1 appears to be the best of
> the three paths.  I don't know why B shouldn't use P1.
>

[bo] I am not sure why B will use P1 to connect to A, because it is hard for
B to understand which path is the best. A send B a referral over P1 is
bacause only P1 is known at the beginning of communication. A can tell B
there are three paths, but cannot tell B which one is the best.
And in the real world, could you give me an example why A will give B three
path. For my knowledge, A always tells B only one path. Or you want to say
the communication between A and B support MIF scenario?

>
> Do you have a better way to represent that in ASCII that
> gets the point across?  Picture worth a thousand words
> and all..
>
> I thought your picture was okay for the case you were describing, but I
> probably didn't look at it too closely as this is all familiar to me
> already.
>
> Keith
>
>
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-- 
Regards,

Bo Zhou
China Mobile