proc StartStopDeviceGroupProtocolNgpf { deviceGroupList action protocol } {
    # Description: 
    #     Only start|stop a protocol for specific device group.
    #     Every other protocol on the device group will not be touched.

    # deviceGroup = One or more device group in a list.
    #               Handle should be provided by HLT or user must know
    #               how to retrieve the device group handle somehow.
    #               Handle style: /topology:1/deviceGroup:1
    # action   = start or stop
    # protocol = Only one protocol

    # protocol:
    #    bgpIpv4Peer, dhcpv4relayAgent, dhcpv4server, greoipv4, igmpHost, igmpQuerier
    #    lac, ldpBasicRouter, ldpConnectedInterface, lns, ospfv2, pimV4Interface, port
    #    ptp, rsvpteIf, vsvpteLsps, staticMPLS, tag, vxlan

    set supportedProtocols "bgpIpv4Peer, dhcpv4relayAgent, dhcpv4server, greoipv4, igmpHost, igmpQuerier lac, ldpBasicRouter, ldpConnectedInterface, lns, ospfv2, pimV4Interface, port, ptp, rsvpteIf, vsvpteLsps, staticMPLS, tag, vxlan"

    if {$action == "start"} {
	set action startIGMP
    }
    if {$action == "stop"} {
	set action stopIGMP
    }

    set root [ixNet getRoot]

    foreach deviceGroup $deviceGroupList {
	foreach topology [ixNet getList $root topology] {
	    foreach deviceGroupObj [ixNet getList $topology deviceGroup] {
		# HLT returns handles like this: /topology:1/deviceGroup:1
		# But full path is like this: ::ixNet::OBJ-/topology:1/deviceGroup:1
		if {[lsearch -regexp $deviceGroupObj $deviceGroup] != -1} {
		    foreach ethernet [ixNet getList $deviceGroupObj ethernet] {
			foreach ipv4 [ixNet getList $ethernet ipv4] {
			    # protocolObjDiscovered: ::ixNet::OBJ-/topology:1/deviceGroup:1/ethernet:1/ipv4:1/igmpHost:1
			    set protocolObjDiscovered [ixNet getList $ipv4 $protocol]
			    if {$protocolObjDiscovered != ""} {
				catch {ixNet execute $action $protocolObjDiscovered} errMsg
				if {$errMsg != "::ixNet::OK"} {
				    puts "\nError StartStopDeviceGroupProtocolNgpf: Failed to start NGPF $protocol on $deviceGroupObj\n"
				    return 1
				} else {
				    puts "\nStartStopDeviceGroupProtocolNgpf Success: $action NGPF on $deviceGroupObj\n"
				}
			    } else {
				puts "\nError StartStopDeviceGroupProtocolNgpf: $protocol is not configured on $deviceGroup. If $protocol is configured on $deviceGroup, verify correct protocol spelling:\n\n$supportedProtocols\n"
			    }
			}
		    }
		}
	    }
	}
    }
    return 0
}