| US 7,558,878 B2 | ||
| Optimal sync for rapid spanning tree protocol | ||
| Shyamasundar S. Kaluve, Santa Clara, Calif. (US); and Norman W. Finn, Livermore, Calif. (US) | ||
| Assigned to Cisco Technology, Inc., San Jose, Calif. (US) | ||
| Filed on Jan. 12, 2007, as Appl. No. 11/653,009. | ||
| Application 11/653009 is a division of application No. 10/012006, filed on Dec. 06, 2001, granted, now 7,177,946. | ||
| Prior Publication US 2007/0124498 A1, May 31, 2007 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G06F 15/173 (2006.01); H04L 12/28 (2006.01) | ||
| U.S. Cl. 709—242 [370/256] | 20 Claims |
| 1. A method for transitioning ports of an intermediate network device among a plurality of states, the method comprising the
steps of:
executing a rapid spanning tree protocol (RSTP) on the intermediate network device, the RSTP designating a first port of the
device to a Root Port Role and designating one or more second ports of the device to Designated Port Roles and placing the
one or more second ports in a forwarding state;
subsequent to the step of executing, reassigning the Root Port Role from the first port to a third port of the device and
blocking the first port;
receiving a bridge protocol data unit (BPDU) message on the third port, the BPDU message having a proposal flag that is asserted
(hereinafter proposal-BPDU); and
in response to the proposal-BPDU, maintaining the one or more second ports in the forwarding state.
|