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

["Patrick Lam" <plam@encc.com>]

Thanks Brian.

So, according to what you said, if we have the following example:

AT1: PC = A
IXC: PC = B
AT2: PC = C

where AT = Access Tandem and IXC = inter-exchange carrier.

To make an interLATA call, we will have the following connection:

AT1 -> IXC -> AT2

Would I be right to describe the OPC-DPC-CIC along the path as the following:

A-B-3 -> B-C-4 -> C-X-5 (X is the PC of the EO)

Thanks again,

Patrick.

"Brian F. G. Bidulock" wrote:

> 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 ¦