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Project 2: Simple Window-based Reliable Data Transfer in C/C++
UCLA CS118
COM SCI 118
Project 2: Simple Window-based Reliable Data Transfer in C/C++
1 Goal
The purpose of this project is to use UDP Socket and C/C++ programming language to implement a reliable data
transfer protocol.
2 Instructions
1. In this project, you will be implementing a simple congestion window-based protocol built on top of either
Selective Repeat protocol or Go-Back-N protocol (not stop-wait, not stop-forward protocol) described in the
textbook. It’s up to you which protocol you will work on. You must write one program implementing the
sender side, and another program implementing the receiver side. Only C/C++ are allowed to use in this
project.
2. The two programs will communicate using the User Datagram Protocol (UDP), which does not guarantee data
delivery.
3. The receiver program will also act as a client application, requesting a file from the sender which acts as a
server.
4. The receiver program will take the hostname and port number of the sender, and the name of a file it wants
to retrieve from the sender as a command line arguments. For example:
to run the sender type: shell sender < portnumber
to run the receiver type: shell receiver < sender hostname < sender portnumber < f ilename
5. The receiver will first send a message to the sender which includes the name of the file requested. If the file
exists, the sender will divide the entire file into multiple packets (the maximum packet size is 1K bytes), and
then add some header information to each packet before sending them to the receiver. It is up to you what
information you want to include in the header (e.g. Source, Destination port etc...), but you will at least need
a sequence number field. You are free to define what kind of messages you will require, and the format of the
messages. You can create a large file being requested on your own, but make sure the file is transmitted in
multiple packets.
6. Note that your programs will act as both a network application (file transfer program) as well as a reliable
transport layer protocol built over the unreliable UDP transport layer.
3 Error Handling
Although using UDP does not ensure reliability of data transfer, the actual rate of packet loss or corruption in LAN
may be too low to test your program. Therefore you should simulate packet loss and corruption in the following
manner:
• Packet loss: With probability Pl
ignore arriving packets (pretend not receiving the arriving packets).
• Packet corruption: With probability PC mark an arriving packet as being corrupted (pretend the arriving
packets are corrupted).
• Pl and PC range between 0 and an appropriate value (say, 0.40). Note both data packets traveling from sender
to receiver and acknowledgement packets traveling from receiver to sender may be lost or corrupted.
1
UCLA CS118
4 Hints
The best way to approach this project is in incremental steps. Do not try to implement all of the functionality at
once.
First, assume there is no packet loss or corruption. Just have the sender send a packet, the receiver respond
with an ACK, and so on. Secondly, introduce corruption. This means you must implement some retransmission
functionality. Thirdly, introduce packet loss. Now you have to add a timer at the sender side for each packet.
The credit of your project is distributed among the required functions. If you only finish part of the requirements,
we still give you partial credit. So please do the project incrementally.
To demonstrate your programs, you can make the window size CW nd, the packet loss probability Pl
, the packet
corruption probability PC , as input parameters when you first run your server and client programs.
For example, to run the sender side: sender < portnumber CW nd Pl PC
and to run the receiver side: receiver < sender hostname < sender portnumber < f ilename Pl PC
You should print messages to the screen when the server or the client is sending or receiving packets. Your
message should include information such as whether it is a DATA packet or an ACK, the sequence number, whether
it is corrupted or lost etc. Such messages will be helpful for you to debug the programs, and we can use them to
examine the correctness of your programs.
5 Due Time and Demo
1. You are required to demo your program on Thursday(6/5) and Friday(6/6).
2. Submit an electronic copy of the project on courseweb on 11:59pm Wednesday(6/4).
5.1 Demo
In the demo, we provide you the provided VM machine. You then use make to compile your programs, run your
programs to deliver a test file from the sender side to the receiver side. It is required by your program to print out
the operations, which explain the delivery process on the screen. We may ask you to use different values for Pl and
PC to test your programs. We will ask you to compare the received test files with the original one using the tool ”diff”.
Demo Procedure:
1. Sign up for Demo : TA will distribute the signup sheet in the discussion section of the 8th week.
2. In Demo : You need to prepare 3 slides to present. 1 slide for design and implementation, 1 slide for experiences
you gain, 1 slide for lesson learn from project and suggestion to project.
• TA will ask you to demo the function step by step
• TA will also ask you questions during demo, you need to answer the question clearly. All question will
related to your project implementation.
6 Project Submission
1. Put all your files into a directory, must called project2 UID.tar. UID is the student id of one of the students
of the group.
2. Submit the file project2 UID.tar via SEAS online submission in course webpage.
3. The project2 UID.tar should contain the following files
• Source codes (can be multiple files)
2
UCLA CS118
• A report file (.doc or .pdf) no more than 3 pages. The report will contain:
– Student names and Student IDs at the very beginning (3 students per-group).
– Implementation description (header format, messages, timeouts, window-based protocol etc).
– Difficulties that you faced and how you solved them.
• Makefile
4. The TAs will only type “make” to compile your code, make sure your Makefile works in the provided VM
machine.
5. Each group just needs to submit one set of files.
3
COM SCI 118
Project 2: Simple Window-based Reliable Data Transfer in C/C++
1 Goal
The purpose of this project is to use UDP Socket and C/C++ programming language to implement a reliable data
transfer protocol.
2 Instructions
1. In this project, you will be implementing a simple congestion window-based protocol built on top of either
Selective Repeat protocol or Go-Back-N protocol (not stop-wait, not stop-forward protocol) described in the
textbook. It’s up to you which protocol you will work on. You must write one program implementing the
sender side, and another program implementing the receiver side. Only C/C++ are allowed to use in this
project.
2. The two programs will communicate using the User Datagram Protocol (UDP), which does not guarantee data
delivery.
3. The receiver program will also act as a client application, requesting a file from the sender which acts as a
server.
4. The receiver program will take the hostname and port number of the sender, and the name of a file it wants
to retrieve from the sender as a command line arguments. For example:
to run the sender type: shell sender < portnumber
to run the receiver type: shell receiver < sender hostname < sender portnumber < f ilename
5. The receiver will first send a message to the sender which includes the name of the file requested. If the file
exists, the sender will divide the entire file into multiple packets (the maximum packet size is 1K bytes), and
then add some header information to each packet before sending them to the receiver. It is up to you what
information you want to include in the header (e.g. Source, Destination port etc...), but you will at least need
a sequence number field. You are free to define what kind of messages you will require, and the format of the
messages. You can create a large file being requested on your own, but make sure the file is transmitted in
multiple packets.
6. Note that your programs will act as both a network application (file transfer program) as well as a reliable
transport layer protocol built over the unreliable UDP transport layer.
3 Error Handling
Although using UDP does not ensure reliability of data transfer, the actual rate of packet loss or corruption in LAN
may be too low to test your program. Therefore you should simulate packet loss and corruption in the following
manner:
• Packet loss: With probability Pl
ignore arriving packets (pretend not receiving the arriving packets).
• Packet corruption: With probability PC mark an arriving packet as being corrupted (pretend the arriving
packets are corrupted).
• Pl and PC range between 0 and an appropriate value (say, 0.40). Note both data packets traveling from sender
to receiver and acknowledgement packets traveling from receiver to sender may be lost or corrupted.
1
UCLA CS118
4 Hints
The best way to approach this project is in incremental steps. Do not try to implement all of the functionality at
once.
First, assume there is no packet loss or corruption. Just have the sender send a packet, the receiver respond
with an ACK, and so on. Secondly, introduce corruption. This means you must implement some retransmission
functionality. Thirdly, introduce packet loss. Now you have to add a timer at the sender side for each packet.
The credit of your project is distributed among the required functions. If you only finish part of the requirements,
we still give you partial credit. So please do the project incrementally.
To demonstrate your programs, you can make the window size CW nd, the packet loss probability Pl
, the packet
corruption probability PC , as input parameters when you first run your server and client programs.
For example, to run the sender side: sender < portnumber CW nd Pl PC
and to run the receiver side: receiver < sender hostname < sender portnumber < f ilename Pl PC
You should print messages to the screen when the server or the client is sending or receiving packets. Your
message should include information such as whether it is a DATA packet or an ACK, the sequence number, whether
it is corrupted or lost etc. Such messages will be helpful for you to debug the programs, and we can use them to
examine the correctness of your programs.
5 Due Time and Demo
1. You are required to demo your program on Thursday(6/5) and Friday(6/6).
2. Submit an electronic copy of the project on courseweb on 11:59pm Wednesday(6/4).
5.1 Demo
In the demo, we provide you the provided VM machine. You then use make to compile your programs, run your
programs to deliver a test file from the sender side to the receiver side. It is required by your program to print out
the operations, which explain the delivery process on the screen. We may ask you to use different values for Pl and
PC to test your programs. We will ask you to compare the received test files with the original one using the tool ”diff”.
Demo Procedure:
1. Sign up for Demo : TA will distribute the signup sheet in the discussion section of the 8th week.
2. In Demo : You need to prepare 3 slides to present. 1 slide for design and implementation, 1 slide for experiences
you gain, 1 slide for lesson learn from project and suggestion to project.
• TA will ask you to demo the function step by step
• TA will also ask you questions during demo, you need to answer the question clearly. All question will
related to your project implementation.
6 Project Submission
1. Put all your files into a directory, must called project2 UID.tar. UID is the student id of one of the students
of the group.
2. Submit the file project2 UID.tar via SEAS online submission in course webpage.
3. The project2 UID.tar should contain the following files
• Source codes (can be multiple files)
2
UCLA CS118
• A report file (.doc or .pdf) no more than 3 pages. The report will contain:
– Student names and Student IDs at the very beginning (3 students per-group).
– Implementation description (header format, messages, timeouts, window-based protocol etc).
– Difficulties that you faced and how you solved them.
• Makefile
4. The TAs will only type “make” to compile your code, make sure your Makefile works in the provided VM
machine.
5. Each group just needs to submit one set of files.
3
1 file (393.9KB)
