Wireless network load generator dynamic MAC hardware address manipulation

• US 7,436,831 B2
• Filed: 12/20/2004
• Issued: 10/14/2008
• Est. Priority Date: 12/29/2003
• Status: Active Grant

• Current Assignee: Keysight Technologies Singapore Sales Pte Ltd (Keysight Technologies, Inc.)
• Original Assignee: Ixia (Keysight Technologies, Inc.)
• Inventors: Bechdol, Jeff A, Miller, Douglas M., Balmy, Ken
• Primary Examiner(s): Chan; Wing F.
• Assistant Examiner(s): Duong; Duc T
• Application Number:
  US11/018,034
• Publication Number:
  US 20050141469A1
• Time in Patent Office: 1,394 Days
• Field of Search: 370/389, 370/392, 370/400, 370/401, 370419-421, 370/463, 370/471
• US Class Current: 370/389
• 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 is disclosed. A host system may emulate multiple, concurrently active stations in the wireless network. Each emulated station is assigned a unique address. A network Medium Access Control (MAC) hardware address of the system'"'"'s wireless network interface is dynamically updated to reflect the address of one of the emulated wireless stations. The method and system allow multiple wireless stations to be emulated with a single network interface device.

Claims

1. A method comprising:

placing a wireless network interface in a promiscuous mode;

receiving via the wireless network interface all frames transmitted on a wireless communication medium;

dynamically reprogramming a MAC address of the wireless network interface as indicated by a current incoming frame;

preparing a virtual station transmit frame for wireless transmission including setting the MAC address of the network interface to the address of a sending virtual station based on a receiver address contained in each current incoming frame on a frame-by-frame basis so that the network interface can send an acknowledgement of receipt for the current incoming frame.

2. The method of claim 1 wherein the dynamically reprogramming further comprises:

comparing a receiver address in the current incoming frame with a plurality of MAC addresses of a plurality of emulated stations;

discarding the current incoming frame if the receiver address does not match any of the plurality of MAC address of the plurality of emulated stations based on the comparing;

reprogramming the network interface MAC address to be the address of the receiver address of the current incoming frame if the receiver address matches one of the MAC address of one of the emulated stations based on the comparing; and

acknowledging receipt of the current incoming frame if the receiver address matches one of the MAC address of one of the emulated stations.

3. The method of claim 1 further comprising:

not performing the dynamically reprogramming if the receiver address of the current incoming frame matches the network interface MAC address.

4. The method of claim 3 further comprising:

keeping the MAC address of the network interface from being changed while the transmission of a frame is in progress.

5. The method of claim 4 further comprising:

discarding incoming frames received while an outgoing frame is being transmitted.

6. The method of claim 1 further comprising:

maintaining a first-in, first-out (FIFO) queue of transmit frame descriptors;

receiving frame descriptors of frames to be transmitted on a network;

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

removing the frame descriptor of a current transmit frame from the FIFO queue when the current transmit frame is successfully transmitted;

reprogramming the MAC address of the network interface with the address of the virtual station of the next transmit frame associated with the frame descriptor in the FIFO queue; and

placing the frame descriptor of the next transmit frame in a hardware transmit queue.

7. The method of claim 6 wherein the hardware transmit queue has a maximum depth of one descriptor.

8. The method of claim 7 further comprising:

removing upon completion of transmission the current transmit frame descriptor from the hardware transmit queue, leaving the hardware transmit queue empty;

placing a next frame descriptor from the FIFO queue in the hardware transmit queue so that the next frame descriptor becomes the current transmit frame descriptor;

removing the next frame descriptor from the FIFO queue;

setting the MAC address of the wireless network interface to the address of the current transmit frame descriptor in the hardware transmit queue;

notifying the network interface of the new contents of the hardware transmit queue;

restarting a transmit protocol of the network interface;

accessing data associated with the current transmit frame descriptor in the hardware transmit queue; and

transmitting the current transmit via the wireless network interface onto the wireless medium.

9. The method of claim 8 wherein the accessing is achieved via a DMA transfer.

10. The method of claim 6 further comprising:

bypassing the software queue if the software queue is empty when a transmit frame is to be enqueued and no other transmission is currently in progress such that the transmit frame is directly processed for transmittal.

11. The method of claim 6 wherein the transmit frame descriptors contain control information for enabling a transmitting protocol system to communicate specific frame handling instructions to frame transmitting hardware, wherein the frame handling instructions enable the frame transmitting hardware to communicate the status of the frame to the transmitting protocol system.

12. The method of claim 1 wherein the network interface is a hardware device or a hardware system.

13. A system to emulate a plurality of virtual stations comprising:

a MAC hardware network interface

a receiving protocol subsystem to

receive a plurality of frames from a wireless communications medium as received frames via the MAC hardware network interface;

generate via the MAC hardware network interface an acknowledgment of a current received frame if a receiver address of the current received frame matches a current address of the MAC hardware network interface;

discard the current received frame if the receiver address of the current received frame does not match any of a plurality of addresses of the virtual stations;

reprogram the MAC hardware network interface if the receiver address of the current received frame matches one of the plurality of addresses of the virtual stations and the MAC hardware interface is not currently transmitting;

a transmitting protocol subsystem to

obtain from a transmit queue a current transmit frame;

map a MAC address of the current transmit frame to the MAC hardware network interface;

transmit onto the wireless communications medium the current transmit frame via the MAC hardware network interface.

14. A system comprising:

a plurality of virtual stations, each having an emulated address;

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

a receiving protocol subsystem coupled with the MAC hardware network interface, the receiving protocol subsystem to

receive frames from the MAC hardware network interface;

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

with those received frames with receiver addresses which match the current MAC hardware interface address, generate an acknowledgement of the receipt of each matching frame;

compare the receiver address of a received frame which does not match the current address of the MAC hardware network interface with the plurality of emulated addresses;

discard those received frames having receiver addresses that do not match any of the plurality of emulated addresses; and

reprogram the MAC hardware network interface with the receiver address of the received frame if the receiver address matches one of the plurality of emulated addresses.