Re: [openss7] [General SS7 question] -- OPC and DPC concept.

["Brian F. G. Bidulock" <bidulock@openss7.org>]

Patrick,

The later in both cases.  Normally for ISUP, the OPC/DPC/CIC in the
ISUP message refers to a specific circuit between two adjacent switches
which have a trunk between them.  For example, for PC A, PC B, and CIC
3, the ISUP message from A to B is labeled A-B-3.  However, for messages
related to the same circuit in the opposite direction, the ISUP messages
are labelled B-A-3.

CIC has no significance throughout an entire call when used in the header
of an ISUP message.

Hope that helps.

--Brian

Patrick Lam wrote:                           Mon, 09 Jul 2001 16:47:38
>
> Hi:
> 
> This is a general SS7 question.  I think these are very basic SS7
> concepts, but somehow I am just a little confused with the OPC, DPC and
> CIC concepts.
> 
> 1.  Do the OPC and DPC represent the point codes of the Calling End
> Office and Called End Office specifically (i.e. the OPC and DPC are
> constant within the whole switched path of a call, and is significant
> all the way from the calling EO to the called EO)?
> Or do they just represent the point codes of two adjacent  switches
> exchanging messages (e.g. an Access Tandem and an IXC)  (i.e. the OPC
> and DPC keep changing along the switched path, and is only significant
> for 2 adjacent switches)?
> 
> 2.  Similar question for CIC:  Is the CIC (Circuit Identification Code)
> constant (and significant) throughout the whole switched path of a
> call?  Or is it only significant between two switches (i.e. keep
> changing whenever it "step by" a switch)?
> 
> Thanks very much in advance,
> 
> Patrick.

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
bidulock@openss7.org    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦