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Megabyte Stream Test ( megtest)

 

megtest is an application-level protocol, that is, it sits at the top of the protocol stack and determines the actions taken by a host during a simulation. A megtest client opens a TCP connection to a megtest server and streams data (default is one megabyte) to the server. The megtest protocol allows us to measure and compare the throughput of the various TCP protocols. The following arguments for megtest may be specified on an args or pargs line.

-buf=<integer>

Specifies the size, in kilobytes, of the TCP send and receive buffers.

-db=<filename>

Specifies the filename in which to print general information about the run. If this option is not specified, this information is not saved.

-dbId=<integer>

After the test, prints the line id: <integer> in the file specified by the -db option.

-dbStr=<string>

Specifies a string to print in the file specified by the -db option after the run has ended. This option is used to print descriptive information about the run, so that multiple runs can be output to the same file and later identified. For example, if one of the important characteristics of a simulation is that all routers use 30 buffers, then the argument, -dbStr=rbufs:30 would print the line rbufs:30 in the output file immediately following the trace information printed by the run. You can have up to 10 different -dbStr per host.

-delay=<integer>[unit]

The delay in (simulated) time units before the test starts. The optional unit can be one of us (microseconds), ms (milliseconds), or s (seconds). The default unit is milliseconds. When running megtest in the presence of background traffic, a delay of a few seconds should be specified in order to give the background connections a chance to stabilize.

-killTraffic

If given as an argument to a single host, after the megtest on this host is done, the traffic is killed and the simulation stops. This option is usually used on the command line after

-all, where it signifies that after all megtest protocols have completed their streaming, all traffic processes are killed and the simulation stops.

-len=<integer>

Sets the amount of data, in kilobytes, to be transferred by the test. The default is 1024, that is, 1MB.

-megTime=<integer>[unit]

Stop the megtest after it has been allowed to run for the specified number of time units, even if the transfer has not completed. The optional unit can be us (microseconds), ms (milliseconds), or s (seconds). The default unit is seconds.

-reset=<integer>

Resets TCP trace information after the specified number of seconds. Often, data about transfers is only of interest after the traffic has had a chance to stabilize, which usually takes a few (simulated) seconds.

-serverPort=<integer>

Used if a single host is running multiple megtest servers, where each server instance must be assigned a port to listen on. A megtest client specifies which server on the host it wants to talk to, by specifying the appropriate port in the client's

-serverPort option.

-showTime

If this option is given, every so often the megtest process prints the elapsed time.

-thresh=<integer>

Specifies the initial threshold variable for TCP's slow start, in 1KB units. The default is one half of the buffer size specified by the -buf option.



next up previous contents
Next: Background Internet Traffic Up: The host Entry Previous: TCP Vegas (



Larry Peterson
Mon Jun 24 16:40:03 MST 1996