FTP Application Development of UDP Based Transport Protocol for Satellite Based Grid Technology

Abstract

Satellite can be useful as communication resource in Grid technology, whereas Grid is useful in effective satellite resource management. Grid protocols are normally written over TCP/IP. Standard transport protocol TCP/IP cannot be used here, as throughput of TCP/IP is inversely proportional to RTT and also bandwidth being costly resource in satellite environment. So for this Satellite based Grid Technology Project, we planned to work out protocols to suite Grid and communication satellite environment. A lot of efforts are going on the modification of TCP (TCP-variants) and the introduction of new protocols (UDP-variants). For high bandwidth, higher window size (RFC 1323) is needed. This can be done by window enhancing mechanism, which requires special skills for tuning the OS. In UDP, there is no such constraint but disadvantage is there is no acknowledgement. But for grid data transfer we need acknowledgement. Both literature survey and simulation experiments studies demonstrate that Simple Available Bandwidth Utilization Library (SABUL) is suitable for grid data transfer under GSAT-4 Applications Project. SABUL, UDP based protocol which uses TCP for control information exchange and UDP for data information exchange. But SABUL does not support FTP application, which is required in our project to transfer files. There are three approaches to develop this FTP application for SABUL in our project : 1) to develop driver interface for SABUL in GridFTP XIO, 2) to change data connection of FTP from TCP to UDP and 3) to develop SABUL-FTP application.