John R 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:

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.

US Patent:

7551551, Jun 23, 2009

Filed:

Dec 10, 2004

Appl. No.:

11/010225

Inventors:

Clarence Filsfils - Brussels, BE
Stefano B. Previdi - Rome, IT
John Galen Scudder - Ann Arbor MI, US
David D. Ward - Somerset WI, US
Jean-Philippe Vasseur - Dunstable MA, US
Jim Guichard - Groton MA, US

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04J 1/16
H04J 3/14
H04L 1/00
H04L 12/26

US Classification:

370219, 370220, 370221, 370228

Abstract:

A fast reroute (FRR) technique that may be deployed at the edge of a network having first and second edge devices coupled to a neighboring routing domain. If the first edge device detects a node or link failure that prevents it from communicating with the neighboring domain, the first edge device reroutes at least some data packets addressed to the neighboring domain to the second edge device. The second edge device receives the rerouted packets and then forwards the packets to the neighboring domain. Notably, the second edge device is not permitted to reroute the received packets a second time, e. g. , upon identifying another inter-domain node or link failure. As such, loops are avoided at the edge of the network and packets are rerouted to the neighboring routing domain faster and more efficiently than in prior implementations.

US Patent:

7639688, Dec 29, 2009

Filed:

Jul 18, 2005

Appl. No.:

11/183381

Inventors:

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

Assignee:

Cisco Technology, Inc. - San Jose CA

International Classification:

H04L 12/56

US Classification:

370392, 370230, 370400, 713201

Abstract:

A method and system for protecting valuable resources within an autonomous system network. Address prefixes within the system are designated as valuable and a flag bit is associated with the address within routing tables of routers of the network. Interfaces to border routers are identified and when packets are received at those interfaces, the packets are flagged with a flag or tag bit. The destination address of the received packet is compared to the flag bit associated with the valuable resource prefix, and if the packet is directed to that resource the packet is dropped and/or logged, but the packet is not forwarded to that resource. In specific cases an interface from an external source may be configured to not create the flag or tag bit, wherein that packet will be delivered to the destination prefix of the packet.