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

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

Patrick,

Yes.  Each leg of the call can be uniquely identified by the triple
PC-PC-CIC (where it doesn't matter what order the point codes are
in the triple).  This triple uniquely identifies a call leg in an
entire SS7 network.

--Brian


Patrick Lam wrote:                                          Mon, 09 Jul 2001 17:51:53
> 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 ¦

-- 
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 ¦