21.5 Commands at a glance

Following is a list of commands used for xcp related simulation in ns.

set xcp_src [new Agent/TCP/Reno/XCP]
This command creates an XCP source agent.

set xcp_dst [new Agent/TCPSink/XCPSink]
This command creates an XCP sink.

$ns duplex-link $R0 $R1 BWMb delayms XCP
This code creates a duplex link with specified bandwidth and link delay using an XCP router between node R0 and R1.

$xcp_queue set-link-capacity bandwidth_in_bits_per_sec
This command propagates the link bandwidth information to the xcp queue which uses it for the router feedback calculation.

set tfile [open tfile w]
$xcp_queue attach $tfile
This Tcl command allows a file to be attached for tracing xcp queue parameters.

$xcp_src attach-trace file-descriptor $xcp_src tracevar var-to-traced
This command allows the xcp sources to trace variables.

$queue queue-sample-everyrtt $rtt_value
This command allows the user to set rtt interval values at which variables like packet_drops and queue lengths are measured at the xcp queue.

Queue/XCP set tcp_xcp_on_ 1
This flag lets tcp and xcp flows to use the same xcp router. This flag is a temporary fix and should go away when dynamic queue weights come into effect.