Spanning tree protocol with burst avoidance
View Patent ↗An apparatus and method for controlling bridge protocol data unit bursts is disclosed. The invention in the preferred embodiment is a switching device with a port enabled with a link management protocol and a burst control state machine. The burst control state machine is adapted to receive BPDUs and, under certain conditions, delay responding with its own BPDU falsely advertising itself as the new root bridge. The delay is preferably long enough to enable another bridge to identity the true root bridge. The delay, e.g., a burst control delay, is preferably equal to or less than a Hello time timer value generally defined to be 2 seconds in a Rapid Spanning Tree Protocol standard, for example.
1. A switching device adapted to perform burst control in a data communications network comprising a plurality of bridges, the switching device comprising:
a first port enabled with a link management protocol; and
a burst control state machine configured to:
receive, on the first port, a first bridge protocol data unit (BPDU) from a first bridge of the plurality of bridges;
not respond with its own BPDU falsely indicating itself as a new root bridge; and
transmit, in response to the first BPDU, a second BPDU from the first port a predetermined period of time after the first BPDU, the predetermined period of time long enough to enable the first bridge to identify a new root bridge.
2. The switching device of claim 1 , wherein the predetermined period of time is a burst avoidance delay less than or equal to two seconds.
3. The switching device of claim 1 , wherein the predetermined period of time is less than or equal to a Hello time in accordance with the link management protocol.
4. The switching device of claim 1 , wherein a set of conditions related to the transmit step further comprises: forwarding information associated with the first port is current; and a topology change indicator is false.
5. The switching device of claim 4 , wherein the set of conditions further comprises: the first bridge is not attempting to become a Designated bridge.
6. The switching device of claim 1 , wherein a port role of the first port transitions from Root to Designated if selectedRole is equal to DESIGNATED.
7. The switching device of claim 4 , wherein the forwarding information associated with the first port is current if infols is equal to RECEIVED, and the topology change indicator is false if tcProp is equal to FALSE.
8. The switching device of claim 4 , wherein the first bridge is not attempting to become a Designated bridge if proposing is equal to FALSE.
9. The switching device of claim 1 , wherein the link management protocol is selected from the group consisting of: Spanning Tree Protocol, International Electrical and Electronics Engineers (IEEE) standard 802.1D 2004, Rapid Spanning Tree Protocol, IEEE standard 802.1w, Multiple Spanning Tree Protocol, IEEE standard 802.1Q 2003, IEEE standard 802.1s.
10. The switching device of claim 1 , wherein the a burst control state machine is further adapted, if the set of conditions are satisfied, to automatically transmit the second BPDU from the first port after the first BPDU is received and to transmit the second BPDU from the first port the predetermined period of time after the first BPDU is received based on a burst avoidance control variable.
11. The switching device of claim 10 , wherein the burst avoidance control variable is a user-defined value.
12. A method of controlling bridge protocol data unit (BPDU) bursts in a switching device in a data communications network comprising a plurality of bridges, the switching device comprising:
receiving, on the first port enabled with a link management protocol, a first bridge protocol data unit (BPDU) from a first bridge of the plurality of bridges;
not responding with its own BPDU falsely indicating itself as a new root bridge; and
transmitting, a predetermined period of time after the first BPDU is received, a second BPDU from the first port, the predetermined period of time long enough to enable the first bridge to identify a new root bridge.
13. The method of claim 12 , wherein the predetermined period of time is a burst avoidance delay less than or equal to two seconds.
14. The method of claim 12 , wherein the predetermined period of time is less than or equal to a Hello time in accordance with the link management protocol.