Ring rapid multiple spanning tree protocol system and method
In an embodiment, a method is disclosed for operating a network having a group of bridges connected together to form a ring, each bridge having two ports assigned to the ring to form a group of ring ports. The claimed embodiment includes forwarding information through the ring according to one or more spanning tree instances, each instance designating one of the group of ring ports as a respective alternate port that is in a state of discarding. Responsive to learning of a failure by a bridge within the ring, a determination is made, for each spanning tree instance, whether the bridge contains a respective alternate port and if the bridge contains a respective alternate port, changing the state of the respective alternate port to forwarding.
1. A method of operating a network comprising a plurality of bridges connected together to form a ring, each bridge of the plurality of bridges having first and second ports assigned to the ring to form a plurality of ring ports, the method comprising:
designating one of the plurality of ring ports in the connected bridges as an alternate port in a discarding state for each instance of a plurality of spanning tree instances;
forwarding information through the ring according to the plurality of spanning tree instances; and
responsive to a failure within the ring, clearing respective forwarding tables for each bridge in the ring except a table associated with a bridge port that detects the failure and a bridge port that forwards a failure message, and changing the state of each ring port designated as an alternative port in a discarding state for each of the spanning tree instances from the discarding state to a forwarding state.
2. The method of claim 1 further comprising configuring each of the plurality of bridges such that a ring failure message that conveys information about the failure in the ring is forwarded around the ring.
3. The method of claim 2 further comprising configuring each of the plurality of bridges such that the ring failure message is sent to a respective processor on each of the plurality of bridges.
4. The method of claim 3 wherein a first bridge sends the ring failure message in a first direction around the ring and a second bridge sends the ring failure message in a second direction around the ring.
5. A memory comprising encoded instructions stored thereon for:
designating one of a plurality of ring ports, in a plurality of bridges that are connected to form a ring, as an alternate port in a discarding state for each instance of a plurality of spanning tree instances;
forwarding information through the plurality of bridges that are connected to form the ring according to the plurality of spanning tree instances; and
responsive to a failure within the ring, changing the state of each alternative port within the ring of connected bridges designated as being in a discarding state for each of the spanning tree instances from the discarding state to a forwarding state and clearing respective forwarding tables for each bridge except a table associated with a bridge port that detects the failure and a bridge port that forwards a failure message.
6. The memory of claim 5 further comprising instructions, responsive to the failure within the ring, for sending a ring failure message that is configured for forwarding around the ring and that is also captured and sent to a respective processor associated with each bridge in the ring.
7. The memory of claim 5 further comprising instructions, responsive to the failure within the ring, for sending the ring failure message to a bridge processing entity for further processing.