John G Scudder

Author:

John R. Scudder

ISBN #:

0817302425

Author:

John R. Scudder

ISBN #:

0819147052

Author:

John R. Scudder

ISBN #:

0819147060

Author:

John R. Scudder

ISBN #:

0791402525

Author:

John R. Scudder

ISBN #:

0791402517

Author:

John R. Scudder

ISBN #:

0791451151

Author:

John R. Scudder

ISBN #:

0867209690

US Patent:

7023808, Apr 4, 2006

Filed:

Dec 23, 2003

Appl. No.:

10/743973

Inventors:

David Alexander Ball - Herts, GB
R. Eric Bennett - Ann Arbor MI, US
Martin Hesketh - St. Albans, GB
John Galen Scudder - Ann Arbor MI, US
David D. Ward - Somerset WI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04J 1/16

US Classification:

370238, 307235

Abstract:

A partial best path technique distributes route selection in a routing protocol implementation on a router. The technique also ensures that announced paths received from peers of the router (i. e. , a “load”) are compared in a correct order to select best paths that are then used by the router to forward packets and to advertise to the peers. When employed in a distributed architecture, the technique further reduces memory usage. To that end, the partial best path technique enhances a best path selection algorithm executed by the router to enable dispersion of the received path load among processing nodes or elements of the router, while maintaining the ordering requirement of the algorithm. The partial best path technique essentially provides an enhancement to the best path selection algorithm that selects a subset of paths from a plurality of paths, with that subset being the minimal subset needed to select the best paths.

US Patent:

7286468, Oct 23, 2007

Filed:

Nov 12, 2002

Appl. No.:

10/293162

Inventors:

John Galen Scudder - Ann Arbor MI, US
David Delano Ward - Somerset WI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

G01R 31/08

US Classification:

370219, 370236

Abstract:

A routing system provides for transparent routing system failover by checkpointing route prefixes during normal operation by maintaining a route prefix table. After failure of a primary routing processor, routing with peer routing systems is synchronized through the use of this prefix table. The prefix table is managed by the primary routing processor and is accessible by a backup routing processor at least after failure of the primary routing processor. Upon the detection of a failure, a backup routing processor solicits routes from peer routing systems in response to the failure and generates a backup routing database from the routes received from peer routing systems. The backup routing processor also compares prefixes of routes in the backup routing database with prefixes in the prefix table, and sends route withdraw messages to the peer routing systems for routes having prefixes listed in the prefix table and not identified in the backup routing database.

US Patent:

7355983, Apr 8, 2008

Filed:

Feb 10, 2004

Appl. No.:

10/775877

Inventors:

John Galen Scudder - Ann Arbor MI, US
Muthurajah Sivabalan - Kanata, CA
David D. Ward - Somerset WI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

G01R 31/08

US Classification:

370242, 370216, 370248

Abstract:

A graceful shutdown technique modifies a routing protocol to allow an intermediate node, such as a router, to announce to its peer routers (peers) its intention to be gracefully shutdown and removed from service in a network. By announcing its intention to be removed from service, the shutdown router closes (terminates) all connections with its peers and all original routes advertised on those connections are removed (withdrawn) from service. According to the inventive technique, the shutdown router may continue forwarding packets over the network for a “grace” period of time, i. e. , the router maintains the validity of those original routes so that packets mapped to the routes are not dropped (at least during the grace period). The grace period also allows backup paths to be propagated to each peer and put into service prior to a final withdrawal of the shutdown router's paths from a forwarding information base of the peer. Thus, the grace period enables the network to continue using the shutdown router as a next hop as it re-converges to use the alternate, backup paths.

US Patent:

7415507, Aug 19, 2008

Filed:

Feb 5, 2004

Appl. No.:

10/772827

Inventors:

David Delano Ward - Somerset WI, US
George Suwala - San Jose CA, US
Natarajan Shankar - Fremont CA, US
John Galen Scudder - Ann Arbor MI, US
Andrew Lunstad - Shoreview MN, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

G06F 15/173

US Classification:

709217

Abstract:

Systems and methods include providing a router that may be deployed as multiple logical routers that share a common fast interconnect. These logical routers may functionally serve as core routers, peering routers, aggregation routers, etc. A further aspect of the system and methods is that the resources assigned to a logical router are allocated from a pool potentially including multitude of hardware cards. A further aspect of the system and methods is that a logical router may be independently managed by the owner of the router or by an owner of the logical router.

US Patent:

7461154, Dec 2, 2008

Filed:

Nov 18, 2004

Appl. No.:

10/992499

Inventors:

Rodolphe Figaro - Windham NH, US
David D. Ward - Somerset WI, US
Anca Zamfir - Kanata, CA
John Galen Scudder - Ann Arbor MI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

G06F 15/16

US Classification:

709227, 709238, 370235

Abstract:

A virtual router (VR) communication arrangement enables services on different VRs executing on the same physical router to communicate without utilizing or substantially consuming communication resources, such as a network protocol stack and physical interfaces, of the physical router. The services are illustratively implemented as separately-scheduled VR processes executing on the physical router. A virtual router forwarding information base (vrFIB) is provided within a client socket library of each VR process and is used to determine whether the services are on the same physical router. If so, a lightweight interconnection is created between the services and a message (“packet”) is forwarded over that interconnection to effectuate communication. If the services are not on the same physical router, the packet is sent over the network protocol stack and communication is established using the communication resources of the router.

US Patent:

7477593, Jan 13, 2009

Filed:

Apr 4, 2005

Appl. No.:

11/098173

Inventors:

John Galen Scudder - Ann Arbor MI, US
David D. Ward - Somerset WI, US
Clarence Filsfils - Brussels, BE

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 12/56

US Classification:

370217, 370221, 370225, 370242

Abstract:

A fast reroute (FRR) technique is implemented at the edge of a computer network. In accordance with the technique, if an edge device detects a node or link failure that prevents it from communicating with a neighboring routing domain, the edge device reroutes at least some data packets addressed to that domain to a backup edge device which, in turn, forwards the packets to the neighboring domain. The rerouted packets are designated as being “protected” (i. e. , rerouted) data packets before they are forwarded to the backup edge device. To that end, the edge device incorporates an identifier into the rerouted data packets to indicate that the packets are being FRR rerouted. The identifier may be a predetermined value stored at a known location in the rerouted packets'encapsulation headers, such as in their MPLS or IP headers. Upon receiving a data packet containing the identifier, the backup edge device is not permitted to reroute the packet a second time.

US Patent:

7496650, Feb 24, 2009

Filed:

Mar 29, 2004

Appl. No.:

10/811626

Inventors:

Stefano Benedetto Previdi - Rome, IT
John Galen Scudder - Ann Arbor MI, US
Clarence Filsfils - Brussels, BE
David Delano Ward - Somerset WI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

G06F 15/173
G01R 31/08
H04L 12/28

US Classification:

709223, 709224, 370229, 370254

Abstract:

One or more sets of routing information are maintained. A network topology change indication of a progressive series of network changes is received, with at least one more associated network topology change indication of the progressive series of network changes expected to be received in the future. An updated set of routing information is computed based on the network topology change indication, and a determination is made as to whether or not the updated set of routing information changes nexthop information for one or more routes. In response to determining that the new set of routing information does not change nexthop information for said one or more routes and given the expectation of at least one more associated network topology change indication of the progressive series of network changes is expected to be received in the future, the routing information is not updated based on the updated set of routing information.

US Patent:

7499459, Mar 3, 2009

Filed:

Feb 5, 2004

Appl. No.:

10/772484

Inventors:

John Galen Scudder - Ann Arbor MI, US
David Delano Ward - Somerset WI, US
Paul A. Jensen - Ann Arbor MI, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 12/56

US Classification:

370400, 370389

Abstract:

A system and method for routing in a network according to a routing protocol. In a router having a plurality of route processors, a routing information base (RIB) is partitioned so that it executes as processes on two or more of the plurality of route processors. A first routing protocol process executing on one or more of the route processes determines a route to a destination in a given network and stores the route in a routing information base (RIB) associated with the first routing protocol process. The first routing protocol process updates a global routing information base (gRIB) with the new route. A gRIB process associated with the gRIB then writes the route from the gRIB to the routing information base (RIB) associated with the second routing protocol process.