Fiber-optic star tree network

• US 4,809,362 A
• Filed: 03/13/1987
• Issued: 02/28/1989
• Est. Priority Date: 03/13/1987
• Status: Expired due to Fees

• Current Assignee: The Center For Innovative Technology
• Original Assignee: The Center For Innovative Technology
• Inventors: Claus, Richard O., Sankar, Ashok
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Telesz, Jr., Andrew J.
• Application Number:
  US07/025,692
• Time in Patent Office: 718 Days
• Field of Search: 455/607, 455/601, 455/3, 455/13, 455/606, 455/612, 370/54, 370/1, 370/4, 340/825.02, 340/825.52, 375/3
• US Class Current: 398/61
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0286 WDM hierarchical architectures
• CPC Class Codes: H04L 12/44 Star or tree networks

Abstract

A communication network and method implementing a star-tree topology utilizes conventional hardward and the CSMA/CD protocol. The network comprises in one embodiment at least two sets of user devices, in turn comprised of at least two user devices, connected through optical connectors and intelligent hubs to one another. Within each set of devices, the devices themselves are connected together by optical connectors through an optical coupler and an intelligent hub.

The method according to one embodiment involves the steps of assigning unique addresses to each hub and subhub in the network and of assigning a device address to each user device. The device address need only be different from the addresses of the other devices in the family. The messages are sent from any one station through a passive coupler to all the other stations connected thereto. If an exclusive OR situation exists whereby either but not both the subhub of the family is the source subhub or the destination subhub then that subhub copies the message and rebroadcasts the message either to its own family or to its parent.

Claims

1. A method of transmitting messages between at least two of a plurality of stations connected together in a fiber optic star-tree communications network wherein, any station can be a source or a destination of the message being transmitted, said network comprising at least a first and a second family of stations, all stations within a family having different addresses, and wherein said first family of stations are connected together and said second family of stations are connected together, respectively, with optical connecting means in a star configuration at respective first and second central passive optical couplers, a first and second parent hub, each parent hub having a unique address and said first and second parent hubs respectively connected to said first and second optical coupler, said first and second hubs also being connected together with an optical connecting means in a star configuration at a common main passive optical coupler, said method comprising:

assigning a first and second part destination address to a message to be sent, said first destination address part containing the address of the destination hub and said second destination address part containing the address of the destination station connected to said destination hub;

assigning a first and second part source address to the message to be sent, said first source address part containing the address of the parent hub and said second source address part containing the address of the source station;

transmitting said message from a source station inside the family to said parent hub and to all stations connected to said parent hub;

copying said message at said parent hub only if the message destination is a station outside of the family of the transmitting station, and then retransmitting said message outside said source family to at least one other hub;

copying said parent hub retransmitted message at a receiving hub only if the message destination is a station inside the family of stations of that hub, and then retransmitting said retransmitted message to the family of stations of said receiving hub; and

copying a message by the destination station.

2. The method of communicating messages as claimed in claim 1 wherein said network stations use the CSMA/CD protocol.

3. The method of communicating messages as claimed in claim 2 and further comprising the step of transmitting a message receipt by any hub or station copying said message back to the hub or station from which that hub received the message.

4. The method of communicating messages as claimed in claim 3 and further comprising the step of checking a copied message for errors and only sending a message receipt when no errors are detected.

5. The method of communicating messages as claimed in claim 4 and further comprising the step of retransmitting a message when a receipt signal is not received.

6. The method of communicating messages as claimed in claim 1 wherein said source station transmits a message only after determining that it is not then receiving a message.