一种支持无连接业务的ATM适配层协议实现方案

An ATM Adaptation Protocol Implementation Scheme for Connectionless Service

提出一种宽带终端适配器Ｂ－ＴＡ中用于支持无连接业务的ＡＴＭ适配层（ＡＡＬ）协议实现方案．对业务的适配采用ＡＡＬ３／４，它的功能是在ＡＴＭ层与高层之间实现信元有效负载的拆装，参照ＩＴＵ－Ｔ１．３６３建议，用于无连接业务时ＡＡＬ３／４的业务特定部分（ＳＳＣＳ）可以是空的，本文仅实现ＡＡＬ３／４的会聚子层公共部分（ＣＰＣＳ）及拆装子层（ＳＡＲ）功能，此外，对本方案的处理时延也进行了一定的分析．

Presents an ATM adaptation(AAL)protocol implernentation scheme for connection less services used in Broadband Terminal Adapter(B-TA).AAL protocol is closely connectedwith high layer services. AAL3/4 is supposed to support connectionless services which porovidecell payload assembler/disasxembler between ATM layer and higher layer. According to ITU-Trecommendation I.363,the function of AAL is performed by convergence Sublayer(CS)and seg-mentation and reassembly(SAR)sublayer,CS is subdivided into common part CS (CPCS)andservice specific part CS(SSCS).When AAL3/4 is used to support connectionless services,theSSCS is null.Hence this paper only includes the implementation of CPCS and SAR. The pro-cessing delay also be discussed.