END-TO-END ARGUMENTS IN SYSTEM DESIGN

J.H. Salter, D.P. Reed and D.D. Clark

Presented by Sui-Yu Wang

Introduction

• A design principle that helps guide placement of functions among the modules of a distributed computer system, the “end-to-end argument”

• Functions placed at low levels of a system may be redundant or of little value when compared with the cost of providing them at low level

• Functions should be moved upward in a layered system

End-to-end Argument

• The function in question can completely and correctly be implemented only with the knowledge and help of the application standing at the end points of the communication system.

Example: Care File Transfer• The file transfer program at host A calls the file system to read

the file from the disk and make it disk-format independent• The file transfer program ask the data communication system

to transfer the file using some protocol that needs to split the file into packets

• The data communication network moves the packets from A to B

• The data communication programs removes the packets from the data communication protocol and hands the data to the file transfer program at host B

• The file transfer program ask the file system to write the received data on the disk of host B

Solutions

• Brute force

• End-to-end check and retry

• Improve data transmission reliability

Performance Aspects

• Unreliable communication makes the overall performance suffer

• Over reliable communication eats up the bandwidth

• The end-to-end check of the file transfer application must still be implemented no matter how reliable the communication system is

Other Example of the End-to-end arguments

• Delivery guarantees

• Secure transmission of data

• Duplicate message suppression

• Guaranteeing FIFO message delivery

• Transaction management

Conclusion

• The end-to-end argument is a guideline to help the application and protocol design