Subject: Re: [Fwd: Re: IPSP proposed text (1st approach)]]

From: Dennis Niermann <[email-masked]>
Date: Fri, 02 Nov 2001 14:56:23 -0600

Hi Tolga,
Here are my reasons for disagreeing with your conclusion that
it is better to define the RC as representing a pair of AS's.

1. It makes the definition of AS semantically different for the
IPSP-IPSP case (a pair of AS's) versus the ASP-SGP case (where the 
RC must still represent a single AS because the AS is not paired 
up with another).

2. It changes the semantics of the ASPAC request from its current
meaning
of "to tell a remote M3UA that this ASP is ready to process signalling 
traffic for a particular AS" to something else that I am not even sure
makes any sense.

3. It breaks the ability to use the registration messages and procedures
in their current form since they depend on a RC value to be assigned
to a single routing key (one AS).

4. I believe that it is much easier to manage and understand RCs
assigned
to AS's than to pairs of AS's. An RC per AS grows linearly with the
number
of AS's, whereas an RC per AS-AS pair grows exponentially. 
It is true that for the simple case of a single AS serviced by a single 
IPSP that this is all a non-issue since in both the single ended and the
double ended case you don't even need to use an RC, it is only
interesting
when you consider the more complicated cases.  
Even though between any two pairs of AS's it is point-to-point. 
It is also true that a given IPSP is certainly going to have
associations
with many other IPSPs and/or SGPs. And, its AS(s) is going to be paired 
up with many other ASs.

5. I think that it is a mistake to create specialized behavior and
semantics
for when communicating with another IPSP versus communicating with a SG.

   Dennis

[email-masked] wrote:
> 
> Hi,
> 
> Because of the point-to-point nature of IPSP communciation, it seems to me
> now more logical to identify every AS pair with a unique RC. ASs are
> corresponding to endnodes of the communication. As the name implies, in
> point-to-point communication messages are sent and received between two
> points. This can be achieved only by identifying both of the endpoints for
> a message, if over a single association traffic of more than one AS pairs
> is transferred (if the whole traffic belongs only to one AS pair, then it
> is implied by the association itself)
> 
> As pointed out by Dennis, similar result can be achieved by putting two RCs
> in DATA (one for source AS one for destination AS) but personally I find
> single ended approach more elegant from this point of view.
> 
>     Tolga

[snip]

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