Computing 205/406 & IT8

Tutorial #4

1. In the lecture, it was claimed that the file sharing used in NFS on the department's Unix system was transparent to the user, but that the approach taken in the Novell PC laboratories was not, to the same extent. What does this mean?

2. Explain why a binary mode FTP transfer of a PC text file to a Unix system results in a corrupted file. Then explain why binary mode is the default on the implementation available in the department's PC labs...

3. Why does the control connection in FTP need to use the TELNET NVT specification?

4. BSD Unix introduced a file transfer utility called rcp, analogous to rlogin. What does this do?

5. Why is the XDR library needed in NFS? Under what conditions is the XDR scheme inefficient?

6. (Research questions) Are there alternatives to NFS for Unix filesystem sharing? Can NFS be used other than between Unix systems?

Practical exercises:

• Use ftp (and its enhanced version ncftp) to copy a file from one system to another. Use anonymous FTP to repeat the operations in slide 4 of the lecture. Use netscape to perform anonymous FTP.

• Use ftp to transfer a file from a machine to itself, and then from the machine to another machine on the same LAN. Do the data transfer rates surprise you?

• Experiment with FTP to see how fast you can transfer a file between two Unix systems on a LAN, when the network is busy and when it is idle. Explain the result. Compare the rates of transfer for FTP and NFS on the same LAN. Do the data transfer rates surprise you?