INF5063 - IXP Resources & FAQ

Page for resources and frequently asked questions about the IXP cards. If you have any other questions, please send an email to haavares@simula.no or haakonks@simula.no

 The following talbe gives an overview of the status of the IXP machines in the lab at IFI:

 All IXP machines at IFI are now configured for the week assignment. Please note that you may only reserve one timeslot (max 4 hours) at a time! The reason for this is to allow other user access to the IXP machines as well.

Frequently Asked Questions

Q: My entire code is suddenly crashing, and I did nothing except allocating some new variables..... What's happening?

A: There might be some issues with your allocation of SRAM. Try to use local mem, registers or DRAM.

Q: Are there some good tools for monitoring packets and bandwidth?

A: We have provided you with tcpdump, wireshark and iptraf

Q: Why doesn't  my program work after I renamed the executable and run it directly?

A: The command wwbump on the IXP is a shell script that loads appropriate modules before starting the executable.

Q: I am worried that other groups can access my code since all have root access...

A: Nothing here is 100% safe. You can however use the svn repository at IFI from the IXP-machines, and checkout right before you test the program, and delete when finished.

Q: How do I inspect packet dumps?

A: The best method is to dump with tcpdump and copy the dump to your local machine for inspection in wireshark. You can use scp for this. Wireshark discourages running the  program as root.

Example:

    $ tcpdump -i eth1 -s0 -w dump.pcap

    $ scp dump.pcap user@linux.ifi.uio.no:.

Q: How do I generate packets?

A: This is not easy. It can be done by using a building block, or by setting up the data structures manually and dequeuing a buffer from the freelist. A simple alternative is to reuse another packet.