The purpose of this document is to describe segmentation and reassembly protocols used on the various MSDL networks. It is our eventual intention to move over to using fully standard compliant headers and adaptation layers. There is however a large body of deployed hardware and software in the Computer Laboratory which pre-dates standardisation attempts. This document describes their formats, and details how they currently inter-operate with standard protocols.
Note should be taken that throughout this document octet numbering is with reference to the FAS fields. For information on the positioning of the FAS fields within a cell or block please consult the EDL, MDL or FDL documentation as appropriate.