| US 7,460,492 B2 | ||
| Spanning tree loop guard | ||
| Maurizio Portolani, Milpitas, Calif. (US); Shyamasundar S. Kaluve, Santa Clara, Calif. (US); and Marco E. Foschiano, San Jose, Calif. (US) | ||
| Assigned to Cisco Technology, Inc., San Jose, Calif. (US) | ||
| Filed on Jun. 12, 2006, as Appl. No. 11/451,888. | ||
| Application 11/451888 is a continuation of application No. 10/020667, filed on Dec. 07, 2001, granted, now 7,061,875. | ||
| Prior Publication US 2006/0233186 A1, Oct. 19, 2006 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. H04L 12/56 (2006.01); H04L 12/28 (2006.01); H04J 3/24 (2006.01); G06F 15/16 (2006.01) | ||
| U.S. Cl. 370—256 [370/402; 370/408; 709/238] | 24 Claims |
| 9. A method for preventing the formation of loops by an intermediate network device having a plurality of ports for receiving
and forwarding network messages to one or more other devices, the method comprising the steps of:
executing a Rapid Spanning Tree Protocol (RSTP) at the intermediate network device to transition at least one of the intermediate
network device's ports among a plurality of port states, including a discarding port state, a listening port state, and a
forwarding port state;
detecting a stoppage of a periodic receipt of bridge protocol data units (BPDUs) on a given port of the intermediate network
device's ports; and
in response to the stoppage, preventing the given port from transitioning to the forwarding port state, if the given port
is in a port state other than the forwarding port state.
|