Recommendation E.710
                          ISDN TRAFFIC REQUIREMENTS OVERVIEW
         1      Introduction
               This  Recommendation  outlines  the  general  consideration  in   modelling
         traffic flows in ISDNs. More detailed  descriptions  for  specific  services  and
         significant points1) in the network are given in  Recommendations  of  the  E.710
         Series as follows:
               E.711 - User Demand
               E.712 - User Plane Traffic Models
               E.713 - Control Plane Traffic Models
               E.714 - Management Plane Traffic Models.
               Additional Recommendations in this Series will be developed in  the  future
         to reflect ISDN developments.
               Note - Recommendations E.712 and E.714 are for further study.
         2      Context
               ISDN concepts,  services  and  networks  are  described  in  the  Series  I
         Recommendations.  The  E.710  Series  of  Recommendations  have  been   developed
         consistent with the approach. However, the grouping  of  material  in  the  E.710
         Series concentrates on the important aspects from a traffic point of view of ISDN
         operations in the immediate future.
               An important modelling technique used to  represent  ISDN  capabilities  is
         the layered architecture described in Recommendations I.310 and I.320. The  E.710
         Series have been developed using this  approach.  At  present  the  E.710  Series
         concentrates on lower layer (1-3) traffic flows. Higher layer traffic  flows  are
         for further study.
               The user  plane/control  plane  perspectives  described  in  Recommendation
         I.320 have been used to provide two separate traffic  models  in  Recommendations
         E.712 and E.713. Nevertheless, it should  be  kept  in  mind  that  many  traffic
         engineering procedures described  in  subsequent  E.700  Recommendations  require
         incorporating traffic loads from  both  planes  using  the  same  resources.  The
         influence of the management plane is for further study.
               The ISDN reference connections used in the E.710 Series are those given  in
         Recommendation E.701.
         3      User demand
               ISDN users have various needs for information transfer. The  user  and  his
         terminal equipment transform these needs  into  a  series  of  call  demands  for
         available ISDN services. These transformations involve many  functions  including
         coding, and peer-to-peer and inter-layer protocols. The  higher  layer  functions
         are not analysed in the E.710 Series.
               Recommendation E.711 starts from the expression  by  the  user  of  a  call
         demand to use the ISDN services  defined  in  Recommendations  I.230  and  I.240.
         Corresponding traffic variables including the number of attempts per call  demand
         are derived for the relevant attributes of each service.
         4      User plane
               In the user plane the  attributes  of  some  ISDN  services  give  rise  to
         additional traffic parameters beyond those used in telephony. Based on  the  user
         models of Recommendation E.711, Recommendation E.712 will  be  developed  in  the
         future to derive traffic models for each basic ISDN service using a common set of
         parameters that applies to all services.
         5      Control plane
               Each attempt from a terminal will result  in  signalling  messages  in  the
         control plane. The number of messages and their length are highly dependent on:
               -   protocols (S.S. No. 7 and Q.931 digital access);
               -   call disposition (including user facilities);
               -   originating and terminating subscriber equipment configurations  (e.g.
                  overlap sending).
               Control plane traffic models given in Recommendation E.713.
         6      Further developments
               The preceding sections of this Recommendation and  the  Recommendations  of
         the E.710  Series  concentrate  on  those  services  and  facilities  which  will
         predominate in the first ISDNs to be implemented.
               However, the ISDN concepts include the inherent possibility  of  developing
         completely new services and functions in response to changing  user  needs.  This

         1) significant points are points in the network where traffic flows and grades of  service
         should be evaluated.



                                                        Fascicle II.3 - Rec. E.710   PAGE1

         will result in new traffic situations that will need to be covered in  the  E.710
         Series. Some of the situations which can be anticipated are:
               -   the impact of supplementary services, such as call waiting, on control
                  plane traffic;
               -   new ISDN  capabilities  such  as  statistical  switching  and  dynamic
                  allocation;
               -   connectionless communications;
               -   the impact of user-to-user signalling;
               -   the impact of multipresentation type calls, and  simultaneous  use  of
                  different interactive and distribution services,  involving  multi-slot
                  and multipoint connections, and broadcast mode.


























































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