GM1 ACNS.B.DLS.B1.105 Transport Layer
Requirements
ED Decision 2013/031/R
Transport Protocol Classes
ICAO Doc 9705 (Edition 2), Sub-volume V, section 5.5 identifies both Connection Oriented and Connection-Less Transport Protocols (as specified in, respectively, ISO/IEC 8073 for COTP and ISO/IEC 8602 for CLTP). The only mandated support is for COTP (i.e. CLTP support is not required).
In addition, ISO/IEC 8073 identifies 5 distinct possible implementations for COTP support, ranging from Class 0 (the less constraining to implement, but also the less reliable) to Class 4 (most reliable). The fifth Class, i.e. COTP Class 4 (also known as ’TP4’), is the only mandated implementation (all other implementations classes are useless for the ATN COTP support).
Transport Protocol Classes
In the ATN Baseline 1 SARPS (i.e. Doc 9705, Edition 2), the Transport Class 4 - as known as TP4 - is as specified in ISO 8073, that mandates support for a 16-bits checksum. Such checksum is considered to be insufficient to detect, and thus compensate, all potential miss deliveries of CLNP Packets by the underlying network routers. The analysis that concluded of TP4 inability to detect and compensate all CLNP miss deliveries is available in ICAO PDR M00040002. The use of a 32-bits long checksum is identified as a solution to address this potential issue.
Loading collections...