Abstract: A method and apparatus for providing data communication between stations on a network which optimizes the amount of resources required for a network switch. A first data frame is encoded with a source station identifier for the first station and a source switch identifier for the first switch. The first data frame is sent from the first switch to the second switch. A station list in the second switch is updated to indicate that the first station is associated with the first switch. Subsequent data frames having the same destination as the first switch are sent directly to the second switch. Any switch on the network need only identify the local ports attached to the switch, plus the number of switches on the network. The task of identifying all of the ports on the network is distributed across all switches on the network.

Abstract: An address reporting technique for reporting address information in a distributed communication environment retrieves locally owned address information from each of a number of distributed address databases, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information. Each address database is maintained by one of a plurality of interconnected modules. A reporting module reports address information by retrieving locally owned address information from its address database, retrieves locally owned address information from each of the other interconnected modules, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information.

Abstract: A distributed address database management technique involves maintaining an address database by each of a number of interconnected modules. Each module maintains a number of locally owned address entries and a number of remotely owned address entries in the address database. Each module monitors the status of its locally owned address entries, maintains the locally owned address entries based upon the status, and provides the status to the other interconnected modules. Each module maintains the remotely owned address entries based upon the status received from the other interconnected modules. When a module adds a locally owned address entry to its address database, the module notifies the other interconnected modules, which in turn add a corresponding remotely owned address entry to their respective address databases.

Abstract: An address reporting technique for reporting address information in a distributed communication environment retrieves locally owned address information from each of a number of distributed address databases, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information. Each address database is maintained by one of a plurality of interconnected modules. A reporting module reports address information by retrieving locally owned address information from its address database, retrieves locally owned address information from each of the other interconnected modules, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information.

Abstract: An address reporting technique for reporting address information in a distributed communication environment retrieves locally owned address information from each of a number of distributed address databases, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information. Each address database is maintained by one of a plurality of interconnected modules. A reporting module reports address information by retrieving locally owned address information from its address database, retrieves locally owned address information from each of the other interconnected modules, sorts the address information according to a predetermined sorting scheme, and reports the sorted address information.

Abstract: A distributed address database management technique involves maintaining an address database by each of a number of interconnected modules. Each module maintains a number of locally owned address entries and a number of remotely owned address entries in the address database. Each module monitors the status of its locally owned address entries, maintains the locally owned address entries based upon the status, and provides the status to the other interconnected modules. Each module maintains the remotely owned address entries based upon the status received from the other interconnected modules. When a module adds a locally owned address entry to its address database, the module notifies the other interconnected modules, which in turn add a corresponding remotely owned address entry to their respective address databases.

Abstract: A distributed address database management technique involves maintaining an address database by each of a number of interconnected modules. Each module maintains a number of locally owned address entries and a number of remotely owned address entries in the address database. Each module monitors the status of its locally owned address entries, maintains the locally owned address entries based upon the status, and provides the status to the other interconnected modules. Each module maintains the remotely owned address entries based upon the status received from the other interconnected modules. When a module adds a locally owned address entry to its address database, the module notifies the other interconnected modules, which in turn add a corresponding remotely owned address entry to their respective address databases.

Abstract: A method and apparatus for providing data communication between stations on a network which optimizes the amount of resources required for a network switch. A first data frame is encoded with a source station identifier for the first station and a source switch identifier for the first switch. The first data frame is sent from the first switch to the second switch. A station list in the second switch is updated to indicate that the first station is associated with the first switch. Subsequent data frames having the same destination as the first switch are sent directly to the second switch. Any switch on the network need only identify the local ports attached to the switch, plus the number of switches on the network. The task of identifying all of the ports on the network is distributed across all switches on the network.

Abstract: An enhanced spanning tree protocol for data communications networks having a multi-link trunk. In one embodiment, configuration messages are transmitted from boxes of the data communications network. In one embodiment, the configuration messages that are transmitted through all physical links of the same logical link, or multi-link trunk, include the same port Identifier. A network device that receives the configuration messages is therefore able to identify all of the physical links of a logical link. The enhanced spanning tree protocol according to one embodiment of the present invention considers all of the physical links of a multi-link trunk as a single logical link when identifying and removing loops in the data communications network to form a spanning tree.

Abstract: A method and apparatus for providing data communication between a source station having multiple connections to a first switch and a destination station having multiple connections to a second switch. A trunk identifier to each port on the first switch and each port on the second switch. A data frame is encoded with the trunk identifier for an ingress port on the first switch. The data frame is sent to the second switch from the first switch. A list of egress ports for the destination station is obtained from a station list contained in the second switch. An egress port is selected from the list of egress ports based upon the source address, destination address and trunk identifier. The data frame is sent to the destination station through the selected egress port.

Abstract: A method and apparatus for providing data communication between stations on a network which optimizes the amount of resources required for a network switch. A first data frame is encoded with a source station identifier for the first station and a source switch identifier for the first switch. The first data frame is sent from the first switch to the second switch. A station list in the second switch is updated to indicate that the first station is associated with the first switch. Subsequent data frames having the same destination as the first switch are sent directly to the second switch. Any switch on the network need only identify the local ports attached to the switch, plus the number of switches on the network. The task of identifying all of the ports on the network is distributed across all switches on the network.

Abstract: Bus access is arbitrated among modules connected to a common bus. Each module has a priority level and an arbitration number assigned to it. More than one module can have the same priority level. For each priority level, the arbitration numbers assigned are unique. When two or more modules attempt bus access at the same time, the one with the higher priority level wins access. If the priority levels are the same but one module has already accessed the bus, the module that has been waiting wins access. If the modules have the same priority level and have been waiting then the module with the highest arbitration number wins access.

Abstract: A method and an apparatus providing data communications among network devices using tagged and untagged frame formats. In one embodiment, a virtual local area network (VLAN) is implemented using frames that may be transferred among network devices in both tagged and untagged formats. In one embodiment, the frames are transferred among network switches in an untagged format, independent of whether the source devices sent the frames in a tagged or untagged format. In addition, destination devices may receive frames in either a tagged or an untagged format, independent of whether the source devices originally send the frames a tagged or untagged format. Cyclic redundancy check (CRC) code information contained in the frames as originally sent is left unchanged when transferred among the switches of the VLAN, even though the frames may have been modified prior to transfer among switches.

Abstract: A method and an apparatus for adjusting an interpacket gap. In one embodiment, a plurality of network devices are tightly coupled together in series. Data is transmitted and received by the network devices in packets with interpacket gaps interposed between each packet. Buffers are included in each network device to serve as elasticity buffers for the data being transmitted between the network devices. The first upstream network device transmits interpacket gaps having an increased size. Downstream network devices may shrink increased size interpacket gaps to reduced size interpacket gaps if the internal buffers are filled to or above a high water mark. However, downstream network devices are not allowed to shrink the size of reduced size interpacket gaps that are received, even if their internal buffers are filled to or above the high water mark.

Abstract: An arbitration unit contains a method of arbitration which includes distributed arbitration, a priority mechanism to support different classes of traffic, a unique arbitration ID bits for each module, a round robin arbitration within a given priority level to produce fair access to a bus 36, an arbitration timeout, and a bandwidth allocation between priority levels.

Abstract: A network hub for interconnection of modular devices, such as Ethernet repeaters, bridges, and routers is provided. Such a network hub efficiently interconnects the modular devices to each other. The inter-module connection is not through standard Ethernet media cabling or interconnections so that the hop count does not exceed one for all external connections, as defined by IEEE 802.3 Repeater Specification. Timing synchronization is provided by a global synchronization mechanism. Collision detection is provided by a series of lines that distribute the collision to all modules connected to the hub. The network hub comprises an inter-module bus having a backplane, the backplane able to connect to a number of modules, a clock, a method for transmitting data received by a first module across the inter-module bus to a second module and transmitting the data to ports of the second module, and a method for synchronizing the data as it is transmitted by the second module to the clock within the hub.

Abstract: A dynamic threshold data receiver uses a single comparator for both squelch and data detection. The comparator has a high-magnitude threshold when the receiver is squelched and a low-magnitude threshold when the receiver is unsquelched. A squelch signal is provided by squelch control logic responsive to a comparison signal from the comparator. The squelch control logic has an interval timer comparing intervals of the comparison signal to a predetermined duration of time, and the squelch control logic changes the squelch signal from the asserted state to the unasserted state after the interval timer determines that the magnitude of the signal level on the comparator input has exceeded the high-magnitude threshold for at least said predetermined period of time.