System and method for providing network route redundancy across Layer 2 devices
View Patent ↗Systems and methods are described for providing network route redundancy through Layer 2 devices, such as a loop free Layer 2 network having a plurality of switching devices. A virtual switch is coupled to the loop free Layer 2 network, the virtual switch having two or more switches configured to transition between master and backup modes to provide redundant support for the loop free Layer 2 network, the switches communicating their status through use of a plurality of redundancy control packets. The system also includes means for allowing the redundancy control packets to be flooded through the Layer 2 network. The means may include time-to-live data attached to the redundancy control packet which is decremented only when the packets are transferred through devices which are configured to recognize the protocol used in redundancy control packets.
1. A system for providing route redundancy for a Layer 2 network comprising:
a loop free Layer 2 network comprising a plurality of switching devices;
a virtual switch coupled to the loop free Layer 2 network comprising two or more switches configured to transition between a master mode, a master confirm mode, and a backup mode to provide redundant support for the loop free Layer 2 network, the switches communicating their status through use of a plurality of redundancy control packets; and
means for allowing the redundancy control packets to be flooded through the Layer 2 network.
2. The system of claim 1 , wherein the Layer 2 network is controlled by a fault recovery protocol.
3. The system of claim 2 , wherein the fault recovery protocol is spanning tree protocol.
4. The system of claim 1 , wherein the redundancy control packets contain a priority data value.
5. The system of claim 4 , wherein the two or more switches in the virtual switch each compare the priority data value contained in a given received redundancy control packet with a stored priority data value to determine whether to be in backup or master mode.
6. The system of claim 5 , wherein a switch in the virtual switch transitions to backup mode upon receipt of a redundancy control packet having a priority value data greater than the stored priority data value.
7. The system of claim 5 , wherein a switch in the virtual switch transitions to master mode if no redundancy control packet is received within a given amount of time containing a priority data value greater than the stored priority data value.
8. The system of claim 4 , comprising a switch in the virtual switch updating its stored priority data value based at least upon status of one or more connections between the switch and one or more devices.
9. The system of claim 1 , wherein the means for allowing the redundancy control packets to be flooded through the Layer 2 network comprises a timing mechanism attached to the redundancy control packets.
10. The system of claim 9 , wherein the timing mechanism comprises time-to-live data included in the redundancy control packets, and means for decrementing the time-to-live data only when the redundancy control packet is transferred through a device configured to interpret the redundancy control packet.
11. The system of claim 1 , comprising means for authenticating redundancy control packets.
12. The system of claim 1 , wherein the redundancy control packets include a timer used by one or more switches in the virtual switch in backup mode to synchronize their timing with that of the master switch which transmitted the redundancy control packet.
13. The system of claim 1 , wherein the virtual switch is coupled to two or more VLANs.
14. The system of claim 13 , wherein the switches in the virtual switch are configured to assume a different mode with respect to each ULAN to which the virtual switch is coupled.
15. The system of claim 14 , comprising means for associating a redundancy control packet with a given one of the coupled VLANs.
16. A method for providing redundancy to a loop free Layer 2 network of arbitrary configuration, the method comprising:
coupling a virtual switch to the Layer 2 network, the virtual switch comprising two or more switches configured to transition between a master mode, a master confirm mode, and a backup mode to provide redundant support for the Layer 2 network;
one or more of the switches in the virtual switch transmitting redundancy control packets, the redundancy control packets including time-to-live data;
flooding the redundancy control packets through the Layer 2 network; and
decrementing the time-to-live only when the redundancy control packet is transferred through a device configured to interpret the redundancy control packet.
17. The method of claim 16 , comprising allowing a user to set a value for the time-to-live data.
18. Computer readable medium storing computer program code which, when executed, causes a computerized Layer 2 switch to perform a method for transitioning between backup and master roles in a virtual switch, the method comprising:
storing a priority value for the switch;
transitioning the switch device to a backup mode if a redundancy control packet is received by the switch having an embedded priority value greater than the stored switch priority value;
transitioning the switch device from the backup mode to a master confirm mode if a redundancy control packet is received by the switch having an embedded priority value less than the stored switch priority value;
when in master confirm mode, transmitting a plurality of redundancy control packets until the switch is transitioned to the backup mode; and
transitioning the switch from the master confirm mode to a master mode if the number of transmitted redundancy control packets reaches a threshold.