(Continuation of Question 23/12 studied in 1997-2000)

Type of question

Task-oriented, leading to new and revised ITU-T Recommendations.

Background

As IP technology is introduced into the PSTN, new attention is being given to the TCP/IP protocol suite. This technology will affect the way that operators think about transport and switching (routing) in their networks, and will have a major impact on the range of services that are available to end users. Issues and guidelines for transmission performance must be reconsidered in light of this shift in the basic technology of voiceband services.

Existing Recommendations on transmission performance were developed for a network that operated using analogue and constant bit rate digital carrier systems (synchronized at least at the primary hierarchical level). As such, these Recommendations do not address many important aspects of packet-based systems such as IP.

As IP technology is introduced for carrying voiceband services, new issues of interconnection of carrier networks will need to be addressed. In particular, interconnection of IP-based long-haul networks with IP-based local networks will need attention.

Text of the question

Considering that IP technology is being introduced into telecommunications networks as both transmission and switching (routing) technology, and that IP technology will be used to provide multimedia and narrowband voice services:

• What new Recommendations are necessary to specify transmission performance for networks using IP technology?
• What Recommendations can be made concerning network planning rules for IP-based networks?
• What planning rules and Recommendations are required to allow interworking between the Switched Circuit Network (SCN, a.k.a. the current PSTN) and networks using IP technology?
• What planning rules and Recommendations are required to allow optimum end-to-end performance when a connection consists of segments from multiple independent IP networks?
• What planning tools are appropriate for making transmission planning decisions in IP-based networks?
• Deployment of IP-based systems will require an understanding of the implications on end-to-end transmission performance of new parameters (e.g. lost packets). What guidance must be given to Study Groups 11, 13, 15 and 16 to ensure that adequate end-to-end performance of voiceband services will occur in IP-based networks?

Study items

The main points of study are:

• identification of transmission parameters (e.g. packet loss, packet delay variation, echo) relevant to IP-based networks for which transmission planning guidance must be provided on order to implement voiceband and multimedia services;
• quantification of the impact on end-to-end transmission quality of these transmission parameters;
• dentification of necessary planning rules for networks that use IP technology.

NOTE - Account should be taken of the work currently under way in other Study Groups, particularly in Study Group 13.

Objectives and schedule

It is anticipated that a new Recommendation G.17x on transmission planning for IP networks will be approved in 2002.

Relationship with other Study Groups

This work will be of interest to ITU-T Study Groups 2, 11, 13, 15 and 16. Liaison should be maintained with these Study Groups, ANSI/T1A1, ETSI/TIPHON, and IETF.