| US 7,477,593 B2 | ||
| Loop prevention techniques using encapsulation manipulation of IP/MPLS field | ||
| John Galen Scudder, Ann Arbor, Mich. (US); David D. Ward, Somerset, Wis. (US); and Clarence Filsfils, Brussels (Belgium) | ||
| Assigned to Cisco Technology, Inc., San Jose, Calif. (US) | ||
| Filed on Apr. 04, 2005, as Appl. No. 11/98,173. | ||
| Prior Publication US 2006/0221813 A1, Oct. 05, 2006 | ||
| Int. Cl. H04L 12/56 (2006.01) | ||
| U.S. Cl. 370—217 [370/221; 370/225; 370/242] | 19 Claims |
| 1. A method for performing fast reroute (FRR) operations at the edge of a computer network, the network having first and second
edge devices coupled to a neighboring routing domain, the method comprising:
detecting a loss of communication between the first edge device and the neighboring routing domain;
receiving a data packet at the first edge device, the received data packet containing a destination address that is reachable
via the neighboring routing domain;
determining whether the received data packet contains a FRR identifier value in at least one of its encapsulation headers,
the FRR identifier value indicating that the received packet was previously rerouted in accordance with FRR operations;
if the received data packet does not contain the FRR identifier value, rerouting the received data packet to the second edge
device for forwarding to the neighboring routing domain; and
if the received data packet does contain the FRR identifier value, dropping the received packet, to prevent loops from developing
at the edge of the computer network.
|