'Simple iperf TCP test between two (optionally specified) hosts.
Usage: iperf node1 node2'

def do_iperf(self, line):

    args = line.split()
    if (not args):
        self.mn.iperf()
    elif (len(args) == 2):
        hosts = []
        err = False
        for arg in args:
            if (arg not in self.mn):
                err = True
                error(("node    '%s'    not    in    network\n" % arg))
            else:
                hosts.append(self.mn[arg])
        if (not err):
            self.mn.iperf(hosts)
    else:
        error('invalid    number    of    args:    iperf    src    dst\n')
