Abstract: A system and method for time synchronization on a network is provided. According to the system and method for time synchronization, a slave clock device does not continuously receive a time synchronization message periodically transferred from a master clock device and thus does not correct its time upon all such occasions. Rather, the slave clock device requests time information from the master clock device only when the slave clock device needs to correct its time, and receives a time synchronization message transferred from the master clock device and compensates for its time deviation only while the slave clock device is activated, thereby reducing its power consumption and amount of computation.

Abstract: The Ethernet packet transmission apparatus includes: a packet transceiving unit for transceiving an Ethernet packet through a plurality of Ethernet ports; a MAC header processing unit for receiving the Ethernet packet and reading header information; a packet processing unit for receiving the Ethernet packet, classifying the received Ethernet packet on a service or destination basis, assigning a priority label to the classified Ethernet packet on a packet-by-packet basis, and outputting memory state information on the corresponding port; a congestion controlling unit for controlling a position in an output sequence of the Ethernet packet; and a signal processing unit for receiving and comparing the port state information and the memory state information and outputting either a memory control signal or a congestion control signal to control the packet processing unit and the congestion controlling unit.

Abstract: Provided are a method and apparatus for dynamically managing hierarchical flows that more efficiently process packet traffic while maintaining compatibility with an existing packet data network in transferring both circuit traffic and packet traffic in a packet switched network. The method for dynamically managing hierarchical flows includes: receiving data packets, classifying the data packets according to attributes of the received data packets, and producing first flows; determining whether traffic of each of the first flows exceeds a predetermined bandwidth limit, and performing a packet drop process or producing second flows for first flows that exceed the bandwidth limit, according to a flow-specific policy; and performing second flow processing on the second flows according to a second flow policy. Only flows exceeding the bandwidth limit or causing congestion are hierarchically divided for management. This makes it possible to finely manage the flows without complex operations.

Abstract: Provided is a dynamic rate-limiting method and apparatus used in a switch for switching packets from input ports to output ports, the method including: (a) adding traffic bandwidth values set in advance in active subscribers that are using the switch from among subscribers connected to the switch; (b) comparing the added value with a range between a maximum bandwidth and a minimum bandwidth that are set in the switch; and (c) according to a result of comparing, when the added values is smaller than the minimum bandwidth or larger than the maximum bandwidth set in the switch, increasing or decreasing the traffic bandwidths of the active subscribers set in advance so that the added value is within the range between the maximum bandwidth and minimum bandwidth. Accordingly, it is possible to automatically control the traffic bandwidths of subscribers that are currently using the switch.