Patent ID: 7801141

Claim:
A method in a network device configured in a true ring network with other network devices, the network device having a first port and a second port connected to the true ring network and a third port connected to a processor, the method comprising: connecting the network device to transmit data packets in a single direction around the true ring network, the first port being an ingress port and the second port being an egress port; enabling ingress source address filtering on the first port and the second port and not the third port; receiving a data packet at the first port of the network device; determining if the source address of the data packet matches a local address of the network device; when the source address of the data packet matches the local address of the network device, terminating the data packet; when the source address of the data packet does not match the local address of the network device, determining if the destination address of the data packet matches the local address of the network device; when the destination address of the data packet matches the local address of the network device, transferring the data packet to the third port; and when the data packet is a multicast data packet for a multicast group in which the network device belongs or a broadcast data packet, transmitting the data packet to the third port and through the egress port, wherein the network device further includes a fourth port coupled to a gateway switch, the gateway switch being connected to a second network, the method further comprising: enabling ingress gateway source address filtering on the first port and the second port and not the third port or the fourth port of the network device; determining if the source address of the data packet matches the local address of the gateway switch; when the source address of the data packet matches the local address of the gateway switch, terminating the data packet; when the source address of the data packet does not match the local address of the gateway switch or the local address of the network device, determining if the destination address of the data packet matches the local address of the network device or the local address of the gateway switch; when the destination address of the data packet matches the local address of the network device, transferring the data packet to the third port; and when the destination address of the data packet matches the local address of the gateway switch, transferring the data packet to the fourth port.