ÿWPCL ûÿ2BJ|xÐ ` ÐÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿH øÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐÐ °°°è ÐÑ Âx„|ü@Ž ÑÐ Å°6Ø'°6Ø'Å ÐÕPÏ Ð ` Ð Áà>Á© ©ƒ Áà<ÁAP IX©145©Eƒ PÕÕPÏ Ð ` Ð Áà>Á© ©ƒ Áà<ÁAP IX©145©Eƒ PÕÕI (3294) ÕÕI (3294) ÕÐ °è  ÐÁà>ÁANNEX Aƒ ÁàAÁƒ Áà5Á(to Recommendation I.350)ƒ ÁàAÁƒ Áà1ÁÓÓÃÃMethod of identifying parametersÄă 1.ÁHÁÃÃThe matrix approachÄÄ Ð H ÐÁHÁThe matrix provides a systematic method of identifying and organizing candidate network performance parameters with the objective of defining a concise set of parameters and, where appropriate, their QOS counterparts. This tool should be used as the basis for collection and evaluation of network performance parameters for digital networks, including ISDNs. 2.ÁHÁÃÃ3x3 matrix approach for network performanceÄÄ ÁHÁThe 3x3 matrix approach for network performance is illustrated in Figure A©1/I.350. The main features are as follows: ÁHÁ1)Âh   Âeach row represents one of the three basic and distinct communication functions;ÆÆ Ð 8 ÐÂHHÂÃÃNoteÄÄ © The access function represents the connectionless as well as connection oriented services which are possible with ISDNs.ÆÆ Ð ` Ð Ð  ÐÁHÁ2)Âh   Âeach column represents one of the three mutually exclusive outcomes possible when a function is attempted;ÆÆ Ð À ÐÁHÁ3)Âh   Âthe 3x3 matrix parameters are defined on the basis of events at connection element boundaries and are termed "primary performance parameters". "Derived performance parameters" are defined on the basis of a functional relationship of primary performance parameters, outage thresholds and an observation interval;ÆÆ ÁHÁ4)Âh   ÂNP primary performance parameters should be defined so as to be measurable at the boundaries of the connection element(s) to which they apply. NP parameter definitions should not depend upon assumptions about impairment causes that are not detectable at the boundaries;ÆÆ ÁHÁ5)Âh   Âavailability is a derived performance parameter. Decisions on the appropriate primary performance parameters, outage threshold and algorithms for its definition require further detailed study.ÆÆ Ð € ÐÂHHÂÃÃNote 1ÄÄ © The following terminology problems are pointed out. Appropriate terms should be selected after further study:ÆÆ Ð ` Ð Ð À ÐÁHÁa)Âh   Âthe term "access" is used. However, the term "selection (of the connection type, the destination and facility)" has been proposed as an alternative;ÆÆ Ô _(ÔŒ ÁàÐEÁFIGURE A©1/I.350ƒ ÁàÐMÁƒ ÁàÐ/ÁÃÃ3x3 matrix approach and determination of availability statesÄă