Wireless network load generator dynamic MAC hardware address manipulation

• US 20050141469A1
• Filed: 12/20/2004
• Published: 06/30/2005
• Est. Priority Date: 12/29/2003
• Status: Active Grant

• Current Assignee: Keysight Technologies Singapore Sales Pte Ltd (Keysight Technologies, Inc.)
• Original Assignee: Communication Machinery Cormporatic
• Inventors: Miller, Douglas M., Balmy, Ken, Bechdol, Jeff A.
• Granted Patent: US 7,436,831 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04L 2101/622 Layer-2 addresses, e.g. medium access control [MAC] addresses
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface

Abstract

A method and system using a single wireless network interface to selectively accept for further processing frames transmitted in a wireless data communications network. This allows a host system to emulate the operation of multiple, concurrently active stations in the wireless network. All wireless stations so emulated adhere to the requirements of applicable standard protocols; particularly, with respect to contention for use of the wireless communications medium and acceptance for further processing of frames transmitted on the medium to an emulated station from a communicating peer station. Each emulated station is assigned a unique address in accordance with the applicable standard protocol. The network Medium Access Control (MAC) hardware address of the system'"'"'s wireless network interface is dynamically updated to reflect the address assigned to a given emulated station as that station becomes active. The present invention is useful in the creation of systems which may thereby concurrently provide interface to the wireless medium on behalf of multiple emulated stations, giving the appearance from the network standpoint of multiple wireless stations which are all in fact operated within a single device.

Claims

1. A method of so sharing a wireless communication network interface among a population of virtual stations as to receive and acknowledge frames addressed to any of those virtual stations, and to process the transmission and acknowledgement of frames on behalf of any of the virtual stations;

that method comprising the steps of;

providing a wireless network interface, which has a MAC address;

placing the interface in a promiscuous mode in which it is capable of receiving all frames transmitted on the wireless communication system; and

dynamically reprogramming the MAC address in the wireless network interface as necessary and as indicated by the current frame to access the wireless communication medium.

2. A method as defined in claim 1 in which;

the receiver address in the incoming frame is compared against the MAC addresses of all of the emulated stations;

the frame is discarded if the receiver address does not match the MAC address of any emulated station; and

,

if the receiver address does match the MAC address of an emulated virtual station, the network interface MAC address is reprogrammed if necessary with the address of that virtual station such that the network interface can acknowledge each frame received by the network.

3. A method as defined in claim 1 in which the network interface MAC address is left unchanged if the receiver address embedded in a received frame matches the current MAC address of the interface.

4. A method as defined in claim 1 in which a virtual station transmit frame is prepared for transmission on the wireless communication system by:

setting the MAC address of the network interface to the address of a sending virtual station as contained in each transmit frame on a frame-by-frame basis so that the network interface can accept an acknowledgement for each such frame.

5. A method as defined in claim 4:

in which a first-in, first-out (FIFO) queue of transmit frame descriptors is maintained and wherein;

frame descriptors are placed in the FIFO queue as frames are transmitted to the network interface by the virtual stations;

the descriptor of the next transit frame is removed from the FIFO queue when one frame is successfully transmitted;

the network interface is reprogrammed if necessary with the address of the virtual station sending the next frame; and

the descriptor of the next frame is placed in a network interface hardware queue.

6. A method as defined in claim 5 in which the hardware descriptor queue has a maximum depth of one descriptor and in the transmission of successive transmit frames handling instructions for each successive frame are supplied between the transmissions of successive frames.

7. A method as defined in claim 6 wherein, upon completion of a frame transmission:

the current transmit frame descriptor for that frame just transmitted is removed from the hardware transmit queue, leaving that queue empty;

the next frame descriptor is removed from the software transmit queue and placed in the hardware transmit queue;

the MAC address in the wireless network interface is set to the address of the emulated virtual station that next frame;

the network interface hardware is notified of the new contents of the hardware transmit queue, and the transmit protocol of the network interface is restarted;

transmit hardware accesses the next frame in the hardware queue; and

the transmit hardware transmits the next frame to peer station via the wireless medium.

8. A method as defined in claim 7 in which the hardware queue is accessed by the transmit hardware via a DMA transfer.

9. A method as defined in claim 5 in which, if the software queue is empty when a transmit frame is to be enqueued and no other transmission is currently in progress, the software queue is bypassed, and the transmit frame is directly processed for transmittal.

10. A method as defined in claim 5 wherein each of the transmit frame descriptor contains control information for enabling a transmitting protocol system to communicate specific handling instructions for the frame to frame transmitting hardware and for enabling the frame transmitting hardware to communicate the status of the frame to the transmitting protocol system.

11. A method as defined in claim 3 which gives precedence to the use of the network interface for frame transmission over the use of that network for receiving frames by keeping the network interface from being changed for so long as the transmission of a frame is in progress.

12. A method as defined in claim 11 wherein, if a date frame is being transmitted when a frame is received from an originating peer station by the network interface, the address of the received frame is discarded and the received frame is not processed.

13. A method as defined in claim 12 wherein the received frame is retransmitted by the originating peer station up to a specified number of times until a transmit frame is not being transmitted by the host system and the network interface MAC address can be reprogrammed with the address of the frame received from the originating station.

14. A method as defined in claim 4 in which the network interface is a hardware device or system.

15. The combination of a wireless network which comprises at least one peer station and a host system with the capability of transmitting frames to the wireless network peer station;

the host system comprising;

at least one virtual station;

a transmitting protocol subsystem; and

a MAC hardware network interface;

the virtual station having the capabilities of preparing a transmit frame and sending the transmit frame to the transmitting protocol subsystem;

the transmitting protocol subsystem having the capabilities of;

obtaining from a header of the transmit frame prepared by the virtual station the MAC address of that virtual station; and

mapping the virtual station address to the MAC hardware interface; and

the MAC hardware network interface having the capability of transmitting the transmit frame to the peer station via a wireless communication medium.

16. The combination of a wireless network which comprises a peer station and a host system with the capability of receiving frames from the wireless network peer station:

the host system comprising;

a plurality of virtual stations;

a MAC hardware network interface set in a promiscuous mode to accept all frames received on the wireless network;

a receiving protocol subsystem with the capabilities of;

determining whether a receiver address contained in a received frame matches the current address of the MAC hardware network interface;

processing those received frames with addresses which match the current MAC hardware interface address and generating an acknowledgement of the receipt of each such frame;

comparing the address of a received frame which does not match the current address of the MAC hardware network interface with the addresses of the virtual stations emulated by the host system;

discarding a received frame if its address does not match an address of any of the virtual stations; and

reprogramming the MAC hardware network interface with the address of the received frame if that address matches a virtual station address.