Re: [uml-devel] Re: What to do with uml_switch?

[Michael Richardson <mcr@sandelman.ottawa.on.ca>]

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>>>>> "Steve" == Steve Schmidtke <steve_schmidtke@hotmail.com> writes:
    Gerd> Hmm, I don't think it is a good idea to put that kind of
    Gerd> testing code into the switch daemon.  I'd make the switch
    Gerd> daemon behave as close as possible to a real switch, then use
    Gerd> the normal tools you use for real networks as well.  I think
    Gerd> uml_switch should just support a monitor port which will see

    >> Not practical, not reliable.

    Steve> Why not reliable?  A monitor port is a diagnostic tool, and

  What would I connect to the monitor port? Another UML? 

  This is the part that isn't practical.
  My test cases sometimes have as many as 7 networks. Remember that we
have 170 test cases, and growing. Remember that we may have packets akin
to "ping-of-death", that may cause the Linux network stack to "oops".
  (this isn't a good, but that's the point of regression tests... is to
make sure that old bugs do not get re-introduced)

  So, we have to start the UMLs for each test, as they may have died.
To make it simple, we start/stop all of the UMLs each time.

  The reason for having the ability to capture and play-back pcap files
in the uml_netjig is to eliminate the need to run as many UMLs.

    Steve> There is no reason you would need to use Linux as your packet
    Steve> source:

    Steve>   cat tcpdump.pcap | switch_mon_tool --socket /tmp/uml.mon
    Steve> --delay 100ms

    Steve> is the type of functionality I'm shooting for (above example
    Steve> not to be taken literally).

  Great. That works for 1 network.

  Now, how do you replay packets where you need an actual time sequence
diagram to make it work? I.e.
	   - send packet A on network 1
	   - send packet B on network 2
	   - send packet C on network 1
	   - send packet D on network 2

  In most cases, we have found round-robin amount input sources works
well, but in that we are disappointed with. 

  Further, remember that you may want to single step the packet sources,
because, you may spend *HOURS* in the debugger (with the UML in
question). That's hard with the method you proposed.

- -- 
]       ON HUMILITY: to err is human. To moo, bovine.           |  firewalls  [
]   Michael Richardson,    Xelerance Corporation, Ottawa, ON    |net architect[
] mcr@xelerance.com      http://www.sandelman.ottawa.on.ca/mcr/ |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [






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