Vocality V200 User Manual page 83

Vocality User Manual
User Manual for V200
Valid for V08_08.02 or V08_48.02
Figure 5-35 Standard TCP session
When a pair of Vocality units is introduced in the connection path between the two
machines then they can be configured to run the performance enhancing proxy:
Figure 5-36 PEP introduced to TCP session
PEP operates by effectively splitting the TCP connection between the two computers
and opening a TCP session at each end locally, thereby avoiding the impairments of the
satellite link. It then sets up a connection between the two sessions with a dynamically
flexible window size, allowing the pipe to remain full at all times across the satellite link.
It uses a 16-bit sequence number to support up to 65,536 packets before waiting for
acknowledgement.
PEP accelerates all TCP-based applications – including Web access, FTP file transfers and
email – by replacing TCP with a protocol specifically optimised for long delay, high bit
error, and asymmetric bandwidth conditions. The user can experience faster
performance of database connectivity, Web applications, and remote access
applications while maintaining full TCP reliability and end-to-end flow control.
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