p.111. it may cause loss of terminal synchronisation. FEC, whilst dramati- Batcher, K.E. (1968) Sorting networks and their applications. In cally improving CLR, can actually adversely affect CLR by con- Proceedings of AFIPS 1968 SJCC, 1968, pp. 307-314. verting an errored header to a valid one but with the wrong VCI CCITT (1990a) Study group XV111 report R.34, (Geneva Meeting value. This effect can be tolerated only because CIR values are May), Recommendations drafted by Working party XV111/8 to much less than CLR values. be approved in 1990. CCITT (1990b) Study group XV111 report R.45, (Matsuyama Session, November), Recommendations to be approved in 1991. 41.5.1.4 Cell delay variation Clos, C. (1953) A study of non-blocking switching networks, Bell System Technical Journal, 32 (2) pp. 406-424. This is the difference between the values of the transit delay of cells Daddis, G.E. et. al. (1989) A taxonomy for broadband integrated belonging to the same VC during a pre-defined period of time switching architectures, IEEE Communications, May. (tentative definition). It is caused mainly by variations in cell delay Dupraz, J., DePrycker, M. (1990) Principles and benefits of the in the network nodes, in particular in the queueing and cell rate asynchronous transfer mode, Electrical Communication, 64 adaptation buffers and can be augmented when asynchronous oper- (2/3). ation is used within the network node. Delay variation can be ETSI (1990) Sub technical committee NA5 (broadband networks). controlled at the receiving terminal at the expense of increased Draft CCITT Contribution: Distributed Scrambler, Report on delay and provision of greater buffer space. With a level of com- rapporteurs meeting, Lannion 22-26 October, pp. 79-85. promise between the requirements on terminals and switching Fisher, D.G., Tat, N., Berglund, A. (1990) A flexible network archi- centres, a maximum peak to peak delay variation of 100 micro-sec- tecture for the introduction of ATM. In Proceedings of the X111 onds per ATM switching centre can be