David Hermes Carroll

US Patent:

6657951, Dec 2, 2003

Filed:

Mar 10, 1999

Appl. No.:

09/266198

Inventors:

David A. Carroll - Apex NC
John K. Fitzgerald - Cary NC
Kara J. Adams - Raleigh NC
Gary William Kramling - Raleigh NC

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 100

US Classification:

370222, 370225, 370244, 370245, 370248, 370250, 370400, 370434, 370445, 370452, 709220, 709229, 709239, 709249, 709251, 714 1

Abstract:

A backup CRF VLAN arrangement provides an alternate, redundant path for traffic between undistributed Concentrator Relay Functions (CRFs) located on separate switches interconnected by trunk links of a distributed token ring bridge. The backup CRF virtual local area network (VLAN) arrangement defines a backup network path which may be utilized if a primary active path is not a valid path to a backup network. Notably, the backup network comprises a special type of CRF that is distributed among the switches, but that has only one port active at any given time.

US Patent:

6674727, Jan 6, 2004

Filed:

Mar 10, 1999

Appl. No.:

09/266241

Inventors:

David A. Carroll - Apex NC
John K. Fitzgerald - Cary NC
Kara J. Adams - Raleigh NC
Gary William Kramling - Raleigh NC

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 12417

US Classification:

370254, 370403, 370410, 370476

Abstract:

A Distributed Ring Protocol (DRiP) arrangement includes a database and protocol for maintaining and distributing information within a distributed token ring (TR) bridge having a logical switch fabric that is distributed over a TR switching network of switches interconnected by trunk links, such as Inters witch Link (ISL) trunks. The DRiP information is used by switches within the ISL switched fabric to determine the status (configured and/or activated) and association (within a switch) of ports of the distributed bridge.

US Patent:

63045753, Oct 16, 2001

Filed:

Aug 31, 1998

Appl. No.:

9/143994

Inventors:

David A. Carroll - Apex NC
Kara J. Adams - Raleigh NC
Kenneth H. Potter - Raleigh NC
Praveen Jain - Santa Clara CA

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 1228

US Classification:

370408

Abstract:

An improved spanning tree protocol for use by token ring intermediate devices having one or more Concentrator Relay Function (CRF) entities and associated Bridge Relay Function (BRF) entities. Each CRF and BRF entity preferably includes a spanning tree engine and corresponding database for individually executing an instance of the spanning tree algorithm and is configured to select a different Bridge Protocol Data Unit (BPDU) message type for use in executing its respective spanning tree algorithm. The selection of BPDU message type by the CRF and BRF spanning tree engines preferably depends on the routing configuration of the associated CRF. The selection of BPDU message type by the CRF entities assures that they are dropped by legacy intermediate devices and only acted upon by the originating CRF or another CRF coupled thereto. The selection of BPDU message type by the BRF entities assures that they are passed through CRF entities unmodified and yet are acted upon by other BRF entities and/or any legacy intermediate devices coupled to the associated BRF entity.