Collision detection in a fiber optic local area network

• US 4,776,041 A
• Filed: 12/04/1986
• Issued: 10/04/1988
• Est. Priority Date: 12/04/1986
• Status: Expired due to Fees

• Current Assignee: Mitre Corporation
• Original Assignee: Mitre Corporation
• Inventors: Husbands, Charles R.
• Primary Examiner(s): Masinick, Michael A.
• Application Number:
  US06/937,733
• Time in Patent Office: 670 Days
• Field of Search: 370/85, 370/94, 455/601, 455/606, 455/607
• US Class Current: 398/61
• CPC Class Codes: H04L 12/44 Star or tree networks

Abstract

The fiber optic local area network includes an active star node including a plurality of optical receivers and transmitters. A logic element is interconnected with the output of each of the receivers in the node to detect simultaneous transmissions on the network. When simultaneous transmissions are detected, a collision signal is generated and this signal is transmitted by the node transmitters onto the network.

Claims

1. Collision detection apparatus in a local network connecting multiple terminals via multiple lines comprising

an active star node including a plurality of optical receivers and transmitters that communicate with said terminals over said multiple lines and also including a transmitter and receiver pair that form an expansion port for connection of one star node to other nodes in a branching architecture, characterized by one star node acting in a head end mode to rebroadcast all traffic on the network and other star nodes acting in a repeater mode,

logic means interconnected with the output of each of the receivers to detect simultaneous transmission on the network;

and

means for generating a collision signal when the logic means detects simultaneous transmission, the collision signal being transmitted by the transmitters onto the network.

2. The apparatus of claim 1 wherein the collision signal has a 10 MHz frequency.

3. The apparatus of claim 1 wherein the active star node further includes a summation logic element for receiving signals from the plurality of optical receivers and for generating a combined signal, the collision signal being added to the combined signal.