The Internet TCP protocol, part of the TCP/IP suite, is one of the cornerstones of the Internet. However, TCP was not designed for optimising resource usage, and has inherent performance problems over many types of satellite links, in particular mobile links. In order to make efficient use of expensive satellite transponder resources, many satellite communication networks use various types of Dynamic Assignment Multiple Access (DAMA) protocols for allocating resources according to the instantaneous needs of the various data streams in the system. Such protocols are typically found in mobile satellite communication as well as in many VSAT systems. The purpose of the work is threefold:
- To develop a new transport protocol for the satellite link, which makes it efficient to use satellites in internet-based networks or multimedia applications while maintaining compatibility with existing applications and networks.
- To investigate methods for explicitly communicating resource requirements and availability between the application and the DAMA control. The preferred solution is one that operates completely within a standard protocol stack, with the exception that the application and the DAMA control need to be aware of each other, and explicitly communicate.
- To include network security features into the architecture. The SaNTA architecture lends itself very well to providing network data security. The original scope of the development has therefore been extended to study this subject and include it into the prototype.
This proposal addresses long-standing problems in satellite communication. It aims at devising a generally applicable solution to the problems, as well as demonstrating this solution within a real satellite communication system. Although several activities are under way in the Internet Engineering Task Force (IETF) to attempt to improve TCP performance over satellite links, no known initiative is looking into replacing TCP with a more suitable protocol (while maintaining application compatibility). In many ESA satellite communications projects, emphasis is put on efficient use of resources, and it is felt that the proposed activity fits well into this picture, and that ESA could have a role world wide in furthering this particular field. Apart from being applicable to mobile satellite and VSAT systems it should also be relevant to terrestrial (cellular) mobile links and wireless LANs.
SaNTA supports the following features:
- TCP acceleration;
- UDP support;
- Support to other internet protocols like: IP, IPSec, XML, ICMP, IGMP, ARP, by transparent and secure tunneling of all other IP-based protocols;
- VPN functionality;
- Security features (SSL/TLS and IPSec);
- Proprietary efficient transport protocol over satellite link (SaSTP);
- End-to-end semantics preservation over heterogeneous network;
- Resource Management mechanism and bandwidth fairness.
The project was successfully completed in November 2005.
Following extensive tests in a lab environment as well as over a satellite link, the project was successfully completed in November 2005.