Agenda Background Project goals Project description –General –Implementation –Algorithms Simulation results –Charts –Conclusions

Project Goals Optimization of inter-proxy communication –improve quality of service for end user (interactive work) by minimizing average proxy response time (average request delay) –improve performance (suitable for batch jobs improvement of total throughput)

These goals can be achieved by: –Implementing different queuing algorithms. –Measuring algorithm efficiency under various number of TCP connections. –Measuring algorithm efficiency under various network conditions (information loss).

General Project Description Our project will zoom on to a couple of proxy servers that intercommunicate by exchanging ICP requests/replies and HTTP data transfers. proxy1proxy2 Control channel(ICP) HTTP

Simplifications ICP implementation isn’t necessary – the server will be supplied with all the relevant information about user data requests. In reality HTTP is used for data transfers. HTTP overhead will be neglected, we will perform data transfers over a number of TCP connections. (All the data transfer will be managed over TCP).

Main thread Data flow Thread 1 Thread 2 Thread 3 Client Server Thread 1 Thread 2 Thread 3 Implementation Scheme

DeQueue(Alg) EnQueue(Alg) request arrives to the system File Transfer Scheme client server timer

Number of connections All TCP connections share the same bandwidth. What is the optimum? Large enough in order to keep the channel busy. –TCP connections may stall as a result of packet loss. Not too large so that TCP overhead is reasonable.

Queuing Algorithms - expectations Round Robin simple algorithm used for reference Single Queue average delay improvement in case of packet losses - maximum connections can treat the same file- least possibility for the file starvation. Categories possibly improves “punishment relation”

Algorithm Description Round Robin Working Threads File0File1File2File3… File0File1File2File3… File0File1File2File3… Queues Naive algorithm File number i is assigned to queue imodN

Algorithm Description Single Queue Working Threads File0File1File2File3… Same queue for all threads

Algorithm Description 4 Categories Working Threads File0File1File2File3… File0File1File2File3… File0File1File2File3… File0File1File2File3… Queue per size category Uniform working thread division per category