File transfer in a global workspaceMarch 14th, 2010 by Jim Elston
Using file transfer in business
In this modern age of information technology file transfer between multiple sites is common place, Businesses are often spread across multiple sites or required to supply files to clients and suppliers in many different formats and locations. Still common is file transfer protocol or FTP, and often businesses have a presence in FTP that allows them to send and receive files easily.
This is a method that works well in the majority of cases and putting aside the security problems associated with this it is a good alternative to email when message limits exist in many corporate environments (large email solutions exist but this are often with third parties such as mailbigfile.com). One of the downsides of file transfer starts being apparent over long distances – ftp bandwidth starts to suffer over these distances due to the nature of the TCP protocol that FTP sits ontop of. This often creates the feeling of ftp latency and an increase in the bandwidth for the FTP application.
TCP is optimised for accuracy in its data stream rather than getting the data to its destination in a timely maner. This often creates long delays (upto seconds) while the stack is waiting for out of order messages or retransmission of lost messages or packets. TCP reacts to out of order messages or lost messages by reducing thr transmission window size which increases the latecy by only allowing a few messages to be sent at any one time untill they are acknolgedged by their destination.
Increasing FTP Bandwidth
As bandwidth becomes ever cheaper businesses are starting to notice they are not getting the best performance out of their FTP bandwidth and an alternative solution is required, in large digital agencies where getting content and files across the globe needs to be accomplished as soon as possible the latency that comes with FTP and other TCP based file transfer solutions is not acceptable.
For a few years now, applications have started to appear on the market that take advantage of TCP’s alternative known as UDP. This protocol does not worry about reliability or order in which the messages arrive at their destination, This means that business are able to fully utilise their file transfer bandwidth. This in itself however, raises other issues, The most prominent is the order in which the messages arrive and how to handle lost data, this is often resolved in the application layer and requires the application to request lost packets or reorder packets that have arrived in the wrong order. This would create an extra overhead on CPU and machine performance but this has little effect in today’s computing power and is one that is acceptable in most scenarios to achieve the best ftp bandwidth and reduce ftp latency.