2.4	Recommendation I.326



REFERENCE CONFIGURATIONS FOR RELATIVE NETWORK RESOURCE REQUIREMENTS





1.	General



	The purpose of this Recommendation is to evaluate the relative network resource requirements associated with the 
provision of ISDN telecommunication services to subscribers as they are defined in the I.200-Series.



	The evaluation of relative network resource requirements and the definition of reference configuration is the first 
step in cost evaluation for ISDN services. Such cost evaluation is not covered in this Recommendation.



2.	Relative resource requirements



2.1	Relation with service provision



	For each service requested by a user the network has to provide network resources. These network resources involve 
switching, signalling and transmission capabilities. The selection of the appropriate network resource is part of the rout-
ing function.



	The combination of permissible network resources is described by the logical concept of ISDN connection types. The 
list of agreed ISDN connection types can be found in I.340.



	The network resources described by an ISDN connection type are:



               +––––––––––––––––––––––+–––––––––––––––––––––––––––+

               |                      |  switching capability    |

               |                      |                           |

               | Network resource     |  transmission capability |

               |                      |                           |

               |                      |  signalling capability   |

               +––––––––––––––––––––––+–––––––––––––––––––––––––––+



FIGURE 1/I.326



Network resource components



	The network resource has an overall scope and may imply several sub- networks, each having to provide an appro-
priate part of the overall network resource.



2.2	Information transfer on network resource usage



	Information on ISDN network resources utilized and that of any interworked networks needs to be gathered for 
charging or for accounting purposes and conveyed to possibly several points within the network(s). Much of this infor-
mation is likely to be derived from data carried on signalling network (e.g. information associated with set-up, clear 
down, and/or change of status of connections). It may be passed in batch-mode between administrations or may be 
conveyed in real-time.



3.	Reference configuration for charging



3.1	Development



	Recommendation I.340 and other relevant Recommendations: I.310, I.324, I.325; are considered as the starting 
point for the development of reference configuration for relative cost evaluation.



	ISDN resources would be represented by network functions as, for example:



	-	transmission functions (local, transit) using different techniques (digital, analogue, speech interpolation ...);



	-	switching functions (local, transit) for circuit-mode,          packet-mode;



	-	interworking functions;



	-	high layer functions.



3.2	Situations



	Reference configurations should include a description of the various situations encountered in international inter-
connections. This description should include the originating country, the boundary, the destination country, interworking 
unit location, international transit.



3.3	Reference configuration for circuit-mode



	The reference configuration for circuit-mode ISDN connection types is made of three connection elements:



	-	Access connection element;



	-	National transit connection element;



	-	International transit connection element.



	The minimum relative resource requirements for international transit connection elements are described in Table 1/
I.326 below:



TABLE 1/I.326

                                                         

  +–––––––––––––––––––––+–––––––––––––––––––––––––––––––+–––––––––––––––––––––+

  |                     |      Possible resources       |       Relative      |

  |  Service request    |     for an international      |       resource      |

  |                     |      transit connection       |      requirement    |

  |                     |            element            |      (see Note 4)   |

  +–––––––––––––––––––––+–––––––––––––––––––––––––––––––+–––––––––––––––––––––+

  |1)  64 kbit/s        |           64 kbit/s           |          1          |

  |    unrestricted     |                               |                     |

  +–––––––––––––––––––––+–––––––––––––––––––––––––––––––+–––––––––––––––––––––+

  |                     |     64 kbit/s, DSI/LRE        |       as low as     |

  |2)  Speech           |     gain 5:1 (see Note 1)     |          0.2        |

  |                     |     A/µ, echo control         |                     |

  |                     |     (see Note 2)              |                     |

  +–––––––––––––––––––––+–––––––––––––––––––––––––––––––+–––––––––––––––––––––+

  |3)  3.1 kHz          |     64 kbit/s, LRE            |       as low as     |

  |    Audio            |     gain 2:1 (see Note 3)     |          0.5        |

  |                     |     A/µ, echo control         |                     |

  |                     |     (see Note 2)              |                     |

  +–––––––––––––––––––––+–––––––––––––––––––––––––––––––+–––––––––––––––––––––+



Note 1 - State-of-the-art voice processing technology is capable of achieving a circuit gain of up to 5:1 on speech 
calls by using a combination of digital speech interpolation (DSI) and low rate encoding (LRE) at 32 kbit/s. Even higher 
gains are conceivable in the future with advances in LRE technology.



Note 2 - The need for echo control in end-to-end ISDN connections is under study.



Note 3 - ISDN services when used to support voice-band data via modems cannot benefit from DSI gains.



Note 4 - The values mentioned in the third column represent relative resource requirements (i.e. traffic allowed in 
terms of bit rate or bandwidth) and should not be interpreted as cost evaluation.



3.4	Reference configuration for packet-mode



	For further study.



3.5	Reference configuration for HLF



	For further study.



3.6	Reference configuration for ALLF



	For further study.



3.7	Reference configuration for Public Land Mobile Telecommunication services



	Reference configuration for Public Land Mobile Telecommunication Systems can be found in Recommendation D.93.