proc VerifyArpNgpf { {ipType ipv4} } {
    # This Proc requires:
    #    1> DeviceGroupProtocolStacksNgpf
    #
    # ipType:  ipv4 or ipv6
    #
    # This API will verify for ARP session resolvement on 
    # every Device Group including inner Device Groups.
    # 
    # How it works?
    #    Each device group has a list of $sessionStatus: up, down or notStarted.
    #    If the deviceGroup has sessionStatus as "up", then ARP will be verified.
    #    It also has a list of $resolvedGatewayMac: MacAddress or removePacket[Unresolved]
    #    These two $sessionStatus and $resolvedGatewayMac lists are aligned.
    #    If lindex 0 on $sessionSatus is up, then $resolvedGatewayMac on index 0 expects 
    #    to have a mac address.  Not removePacket[Unresolved].
    #    If not, then arp is not resolved.
    #
    # Return 0 if ARP passes.
    # Return 1 if device group is not started
    # Returns a list of unresolved ARPs (src ip)

    set startFlag 0
    set unresolvedArpList {}
    foreach topology [ixNet getList [ixNet getRoot] topology] {
	foreach deviceGroup [ixNet getList $topology deviceGroup] {
	    puts "\n$deviceGroup"
	    set deviceGroupStatus [ixNet getAttribute $deviceGroup -status]
	    puts "\tdeviceGroup Status: $deviceGroupStatus"
	    if {$deviceGroupStatus == "started"} {
		set startFlag 1
		set arpResult [DeviceGroupProtocolStacksNgpf $deviceGroup $ipType]
		if {$arpResult != ""} {
		    set unresolvedArpList [concat $unresolvedArpList $arpResult]
		}
		
		if {[ixNet getList $deviceGroup deviceGroup] != ""} {
		    foreach innerDeviceGroup [ixNet getList $deviceGroup deviceGroup] {
			puts "\n$innerDeviceGroup"
			set deviceGroupStatus1 [ixNet getAttribute $innerDeviceGroup -status]
			puts "\tInner deviceGroup Status: $deviceGroupStatus1"
			if {$deviceGroupStatus == "started"} {
			    set arpResult [DeviceGroupProtocolStacksNgpf $innerDeviceGroup $ipType]
			    if {$arpResult != ""} {
				set unresolvedArpList [concat $unresolvedArpList $arpResult]
			    }
			}
		    }
		}
	    } elseif {[ixNet getAttribute $deviceGroup -status] == "mixed"} {
		set startFlag 1
		puts "\tWarning: Ethernet stack is started, but layer3 is not started"
		set arpResult [DeviceGroupProtocolStacksNgpf $deviceGroup $ipType]
		if {$arpResult != ""} {
		    set unresolvedArpList [concat $unresolvedArpList $arpResult]
		}
		
		if {[ixNet getList $deviceGroup deviceGroup] != ""} {
		    foreach innerDeviceGroup [ixNet getList $deviceGroup deviceGroup] {
			puts "\n$innerDeviceGroup"
			set deviceGroupStatus2 [ixNet getAttribute $innerDeviceGroup -status]
			puts "\tInner deviceGroup Status: $deviceGroupStatus2"
			if {$deviceGroupStatus2 == "started"} {
			    set arpResult [DeviceGroupProtocolStacksNgpf $innerDeviceGroup $ipType]
			    if {$arpResult != ""} {
				set unresolvedArpList [concat $unresolvedArpList $arpResult]
			    }
			}
		    }
		}		
	    } else {
		puts "\nVerifyArpNgpf: Protocol not started successfuly on:\n\t$deviceGroup"
	    }
	}
    }

    if {$unresolvedArpList == "" && $startFlag == 1} {
	return 0
    }
    if {$unresolvedArpList == "" && $startFlag == 0} {
	return 1
    }
    if {$unresolvedArpList != "" && $startFlag == 1} {
	puts \n
	foreach unresolvedArp $unresolvedArpList {
	    puts "VerifyArpNgpf: UnresolvedArps: $unresolvedArp"
	}
	puts \n
	return $unresolvedArpList
    }
}