Specifies the protocol to be used to perform the RTT
operation. The following list defines what protocol
should be used for each probe type:
echo, pathEcho - ipIcmpEcho / mplsLspPingAppl
udpEcho - ipUdpEchoAppl
tcpConnect - ipTcpConn
http - httpAppl
jitter - jitterAppl
dlsw - dlswAppl
dhcp - dhcpAppl
ftp - ftpAppl
mplsLspPing - mplsLspPingAppl
voip - voipAppl
video - videoAppl
When this protocol does not support the type, a 'badValue'
error will be returned.