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Job Summary:
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| Job Type: |
Project |
| Budget: |
$ 20-100 |
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(None) |
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| Status: |
Work Performed (selected user rolandm)
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Buyer Summary:
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| Feedback Score: |
1
reviews
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| Award Reliability: |
1 posted 1 paid |
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| Location: |
Astoria, United States
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| Member Since: |
December 5, 2005 |
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There are no invited users
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Description
Need to implement a file transfer protocol using UDP between two computers in Solaries. Please see the note below and attached for details:
14300:
Implementation project.
Computer Communications
Due in 2nd week of Dec. '05 (handed out on 28th Sept) Instructor: K. R
The following protocol is designed to transfer large files (say, about 10-15 megabytes size) from one machine to another machine in full blast, i.e., the protocol generates minimal overhead in terms of acknowledgements and processing. The protocol uses a datagram subnet. To implement the protocol, the sender process first sets up a UNIX interprocess communication path wiith a receiver process, choosing a datagram service at the network layer. Figure 1 shows the various functional components of the file transport system.
The file transfer protocol employed by the system has two entities: the file sender and the file receiver. The protocol has 3 phases, as follows:
Phase 1: For connection setup, the sender sends a file header packet FILE-HDR which contains information on the file size, the record size which can be chosen to be one of {256, 512, 1024} bytes (usually, to match disk block sizes), the name of the file under which the file is to be stored at the receiver (note that a chosen record size does not change thereafter in a given execution). Upon file header acknowledgement by receiving FILE_HDR_ACK, the sender considers the connection setup as successful.
Ph,ase 2: The sender sends the file contents as a sequence of blasts, with each blast containing one or more packets and each packet containing a sequence of file records, totalling a data up to M records per blast (M is in the range of 200-10000, depending on the amount of buffers available at the sender/receiver - this is also a negotiable parameter during connection setup). The maximum number of records that can fit into a packet is 16. The provision for variable number of records in a packet is needed because the reading of file data from disk to transport buffers at the sender, the transport of data between the sender and receiver buffers through the network, and the writing of data from buffers to disk at the receiver may proceed asynchronously. This aspect has to be incorporated into the project. A packet may contain up to N (© 1) segments, with each segment containing a sequence of file records. To allow multiple segments in a packet, the sender prep ends the segments by a list of the form
{(st_rec1 , end_rec1), (st_rec2 , end_rec2) , … , (st_recN, end_recN) }for N © 1.
in the packet header, where st_reci, st_reci | i=1,2,... indicate the record numbers of the first and last records respectively in the ith segment of the packet. At the end of transmission of a blast, the file sender sends a IS_BLAST_OVER (Mst, Mfin) quering the file receiver if all of the records from Mst through Mfin were received. Upon receiving the IS_BLAST_OVER, the file receiver sends a packet REC_MISS containing a list of missing records in the blast cycle Mst - Mfin.The file sender then sends the missing records, again using the same format as before. The procedure repeats until the file sender receives a REC_MISS with an empty list.
Phase 3: Upon receiving a REG_MISS with empty list for the last blast, the file sender disconnects the receiver. The disconnect protocol should allow the file receiver process to linger on for a short period of time to ensure that any potential retransmissions of the IS-BLAST _OYER from the file sender can be responded to.
The file sender has a time out for FILE_HDR and IS_BLAST _OYER to allow retransmission-based recovery from packet loss. Remember that the datagram service can drop packets at will.
Figure 2 shows a timing scenario to illustrate the main features in the data transfer phase of the protocol.
Implement the above protocol on Solaris/Linux using the UDP (User Datagram Protocol) that is supported by the underlying UNIX kernel. The kernel provides a socket interface to the UDP (refer to UNIX system calls on interporcess communications, viz., send, receive, alarm and the related ones.) Your implementation involves: i) coding the protocol state machine (including timeouts), ii) translating the state machine into a UNIX networking program , and iii) testing the program as to wheather it functions correctly under packet loss conditions in the network. You need to measure the maximum throughput rate acievable by the blast protocol under various packet loss rates in the network (for this purpose you will be supplied a 'garbler' module that can inject 'packet loss' in the network at a specified rate). Note that your program should be able to transfer both text and binary files.
At the end of each program run, collect statistics on how many packets were lost in the throughput rate, and submit a report. Be sure to include a graph showing the variation of protocol throughput rate vs packet loss rate in the network.
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