Abstract: Different mechanisms are disclosed for translating native Media Access Control (MAC) addresses to and from corresponding hierarchical MAC addresses, and the use of such MAC addresses. A packet switch typically maintains a data structure relating native MAC addresses of certain devices with external MAC addresses, wherein each of the external MAC addresses is typically hierarchical in nature with a portion of the translated address identifying a switch local to the destination device and through which the destination device is to be reached. Other network elements can then readily determine where to route a packet with a destination identified by such a hierarchical MAC address without having to maintain such a large or complete database of MAC addresses as the packet can be routed to the switch based on a portion of the hierarchical address (e.g., typically without regard to the portion of the address identifying the actual destination device).

Abstract: In one embodiment, a rapid spanning tree protocol (RSTP) is executed on an intermediate network device. The RSTP may designate a first port of the device to a Root Port Role and designate one or more second ports of the device to Designated Port Roles, and place the one or more second ports in a forwarding state. Subsequently, the intermediate network device may reassign the Root Port Role from the first port to a third port of the device and blocking the first port. If the intermediate network device receives a proposal bridge protocol data unit (BPDU) message on the third port, rather than transition the one or more second ports to a blocking state, the intermediate device is adapted to maintain the one or more second ports in the forwarding state.

Abstract: A system and method are provided to prevent the formation of loops in a network. The network device includes a plurality of ports for receiving and forwarding network messages and a spanning tree protocol engine. The spanning tree protocol engine, in one embodiment, implements the Rapid Spanning Tree Protocol (RSTP) to transitions the ports among a plurality port states, including a discarding state, a learning state and a forwarding state. The network device further includes a loop guard engine that is in a communicating relationship with the spanning tree protocol engine and the ports. The loop guard engine monitors the receipt of bridge protocol data units (BPDUs) by the ports. If a given port stops receiving BPDUs, the loop guard engine prevents the spanning tree protocol engine from transitioning the given port to the forwarding state. Instead, the loop guard engine causes the port to transition to loop inconsistent state.

Abstract: Disclosed are, inter alia, methods, apparatus, data structures, computer-readable media, and mechanisms for limiting unauthorized multicast sources. One or more access control lists are typically configured in a switching device to a state that denies forwarding of multicast packets with a particular host as its source. In response to a received multicast application admission-control message identifying the particular host, the one or more access control lists in the switching device are updated to allow multicast messages sent from the particular host to be forwarded. In one system, the received multicast application admission-control message is an Internet Group Management Protocol (IGMP) message.

Abstract: An associative memory with an invert result capability to allow the identification of an entry as being matched when an entry or portion thereof is specifically not matched is disclosed (or alternatively viewed as an entry or portion thereof indicated as matched when it actually was not matched). One such associative memory typically includes multiple associative memory entries, each of which typically includes storage for one or more subsets of bits to be used in matching a lookup value and for one or more invert result indications to identify whether or not corresponding particular subsets of the one or more subsets of bits are to be inverted in producing an entry match result.

Abstract: Different mechanisms are disclosed for translating native Media Access Control (MAC) addresses to and from corresponding hierarchical MAC addresses, and the use of such MAC addresses. A packet switch typically maintains a data structure relating native MAC addresses of certain devices with external MAC addresses, wherein each of the external MAC addresses is typically hierarchical in nature with a portion of the translated address identifying a switch local to the destination device and through which the destination device is to be reached. Other network elements can then readily determine where to route a packet with a destination identified by such a hierarchical MAC address without having to maintain such a large or complete database of MAC addresses as the packet can be routed to the switch based on a portion of the hierarchical address (e.g., typically without regard to the portion of the address identifying the actual destination device).