Concurrent resource request resolution mechanism

• US 4,942,574 A
• Filed: 03/31/1988
• Issued: 07/17/1990
• Est. Priority Date: 03/31/1988
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Zelle, Bruce R.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US07/175,695
• Time in Patent Office: 838 Days
• Field of Search: 370/60, 370/86, 370/89, 370/110.1, 370/85, 340/825.05, 340/825.5
• US Class Current: 370/400
• CPC Class Codes: H04L 12/00 Data switching networks interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units G06F13/00
• CPC Class Codes: H04L 12/56 Packet switching systems

Abstract

A high capacity metropolitan area network (MAN) is described. Data traffic from users is connected to data concentrators at the edge of the network, and is transmitted over fiber optic data links to a hub where the data is switched. The hub includes a plurality of data switching modules, each having a control means, and each connected to a distributed control space division switch. Advantageously, the data switching modules, whose inputs are connected to the concentrators, perform all checking and routing functions, while the 1024×1024 maximum size space division switch, whose outputs are connected to the concentrators, provides a large fan-out distribution network for reaching many concentrators from each data switching module. The data switching modules chain groups of incoming packets destined for a common outlet of the space division switch so that only one connection in that switch is required for transmitting each group of chained packets from a data switching module to a concentrator. MAN provides security features including a port identification supplied by the data concentrators, and a check that each packet is from an authorized source user, transmitting on a port associated with that user, to an authorized destination user that is in the same group (virtual network) as the source user.

In accordance with one enbodiment of the invention, a data ring communicates space division switch outlet availability to each of the data switching modules in turn, in order to resolve the contention among these modules for a particular outlet. Each data switching module maintains a list of outlets for which it has accumulated a group of at least one packet destined for that outlet; a data switching module then seizes an available outlet by marking that outlet unavailable in the data communicated by the data ring.

Claims

1. A resource allocation arrangement for allocating ones of a plurality of resources comprising:

a plurality of controller means; and

data ring means connected to each of said controller means for transmitting availability data for each of said resources among said controller means;

each of controller means comprising;

buffer means for storing a requested resource identification;

interface means for receiving data from and transmitting data to said ring means; and

means for checking a list of requested resources against availability data received by said interface means from said ring means;

wherein said data ring means further comprises means for transmitting priority window data for each of said resources;

wherein said interface means is responsive to said checking means for storing a priority indication for one of said requested sources that is found to be busy while said priority window is open;

wherein said interface means comprises means responsive to said checking means for seizing one of said requested resources that is found to be available in said availability data if a priority indicator for said requested resource for said means for checking is stored or if said priority window is open by transmitting availability data indicating unavailability for said one requested resource to said rings means for transmission to a next controller means connected to said rings means; and

wherein each of said controllers controls a set of controlled resources and wherein said interface means comprises means for copying an availability state to said priority window data for each member of said set of controlled resources.

2. The arrangement of claim 1 wherein only one controller is associated with each resource and a controller associated with a particular resource controls a priority window for said particular resource.

3. A resource allocation arrangement for allocating ones of a plurality of resources comprising:

a plurality of controller means; and

data ring means connected to each of said controller means for transmitting availability data and window state data data for each of said controller means;

wherein each of said resources is associated with only one of said controller means;

each of said controller means comprising;

buffer means for storing a list of requested resources and a priority indication for each member of said list;

interface means for receiving data from and transmitting data to said ring means;

means for checking said list of requested resources against said availability data and said window state data received by said interface means from said ring means;

said interface means responsive to said checking means for seizing one of said requested resources that is found to be available when a window state for that requested resource is open, and for seizing one of said requested resources that is found to be available when said window state for said requested resource is closed and a priority indication for said requested resource is in the priority state, by transmitting availability data to indicate unavailability for said requested resource to said ring means for transmission to a next controller means connected to said ring means;

said interface means responsive to said checking means for marking said priority indicator for a requested resource to a priority state if said requested resource is unavailable and a corresponding window state is open;

each of said controllers responsive to signals from said interface means for copying an availability state to a corresponding window state for resources associated with said each controller.