Subject: COPS : Clarifications

From: Dan Davidson <[email-masked]>
Date: Wed, 24 Jul 2002 09:58:28 +0200

Hi,

	In section 2.3 "Communication" of the COPS protocol (RFC 2748) the
following
sentences can be encountered:

"The COPS protocol uses a single persistent TCP connection between the PEP
and a remote PDP"

a little later in the same section":

"If a single PEP can support multiple client-types, it may send multiple
Client-Open messages, each specifying a particular client-type to a PDP over
one or more TCP
connections".

The question is: How many TCP connections are there ? A single one or
multiples ?

Thanks for the help,
Best Regards,
Dan

---

From: Kwok Ho Chan <[email-masked]>
Date: Wed, 24 Jul 2002 08:30:24 -0400

In normal operation, only a single TCP connection is needed, because
multiple COPS Client OPEN can be multiplexed over the same TCP
connection.  But this does not limit the use of multiple TCP connections
if it is necessary.
-- Kwok Ho Chan --

---

From: Bhattacharjya Probal <[email-masked]>
Date: Wed, 24 Jul 2002 16:35:16 +0800

[ post by non-subscriber.  with the massive amount of spam, it is easy to
  miss and therefore delete mis-posts.  so fix subscription addresses! ]

Please refer to the following reply from David Durham (I hope it's okay with
David to be quoted without permission! ) to the same question a while back.

Regards,
   --Probal.

> -----Original Message-----
> From: Dan Davidson [mailto:[email-masked]]
> Sent: Wednesday, July 24, 2002 3:58 PM
> To: [email-masked]
> Subject: COPS : Clarifications
> 
> 
> Hi,
> 

Subject: RE: Question about COPS RFC (2748)
From: "Durham, David" <[email-masked]>
To: Bhattacharjya Probal <[email-masked]>
Date: Thu, 18 Apr 2002 23:52:21 +0800

Hi Probal,
The COPS protocol using a single persistent connection between the PEP and
remote PDP serving one or more client-types. Multiple client-types between
the same PEP and PDP may share the same or establish multiple TCP
connections (no more than one per client type, however). There is an
efficiency gain if they all share the same TCP connection, but this is not a
MUST.
 
I agree the RFC is not very clear on this. The answer is one or more TCP
connections, no more than one per client-type, with one being the preferred
arrangement.
 
-Dave

-----Original Message-----
From: Bhattacharjya Probal [mailto:[email-masked]]
Sent: Wednesday, April 17, 2002 6:15 PM
To: [email-masked]
Subject: Question about COPS RFC (2748)

Dear Sir, 

I have a possibly silly question about the COPS RFC (RFC 2748) and would
like to have your clarification as the editor of the RFC. In section 2.3
called "Communication" the very first sentence asserts that

"The COPS protocol uses a SINGLE persistent TCP connection between the PEP
and a remote PDP". 

And then in the second paragraph, the first sentence (which spans three
lines) says 

"If a single PEP can support multiple client-types, it may send multiple
Client-Open messages, each specifying a particular client-type to a PDP over
one or MORE TCP connections"

[I have EMPHASISED the parts I want to draw your attention to!] 

My question is if according ot the former sentence there could only be a
"SINGLE" TCP connection between a PEP and a PDP, then how is it according to
the latter sentence that a PEP may send multiple messages to a PDP over
possible "MORE than one" TCP connections?

Is it then possible to have "more than one" TCP connection between a PEP and
a PDP? In that case the former sentence is not correct in asserting that
there could only be a "single" TCP connection between them!!

Please clarify. 

Thanks, 
   --Probal. 

--------------------------------------------------------- 
  
Probal K. Bhattacharjya 
Siemens Pte Ltd