Abstract: A switch device for use in telecommunications apparatus, the switch device comprising: a substantially planar substrate having first substantially planar face and an opposing second substantially planar face; a first plurality of ports mounted on the first face of the substrate, and having a first arrangement of locating pins which extend into the substrate from the first face towards the second face thereof; and a second plurality of ports mounted on the second face of the substrate, and having a second arrangement of locating pins which extend into the substrate from the second face towards the first face thereof, wherein the first arrangement of locating pins is offset with respect to the second arrangement of locating pins.

Abstract: A technique is described for retrieving data from a hash table in an Ethernet bridge. The table has a plurality of columns, each of which has a hash function, thereby creating respective different hash key values.

Abstract: The present invention provides a method of limiting the frequency of floods within a data network, the floods arising as a data frame is routed to an unknown destination, the method comprising the steps of: receiving on an ingress port a data frame intended for a destination station and containing a MAC address of that station; checking the destination MAC address with the contents of a MAC table; and thereby determining whether the data frame is to be routed, discarded or flooded to all ports except the ingress port; and respectively routing, discarding or flooding the data frame to all ports except the ingress port.

Abstract: The present invention relates to data switching networks, and, in particular, to link aggregation groups in Ethernet switching networks. A technique is described in which a large number of links in a link aggregation group can be managed.

Abstract: A method of controlling data packet congestion in a data packet network comprises determining a reference flow condition that results in data packet congestion at a node of a data packet network, and identifying a data packet flow having a flow condition substantially equal to the reference flow condition. For such an identified data packet flow the following actions are taken causing a data packet to be dropped from the identified data packet flow, allowing a predetermined number of data packets from the identified data packet flow to proceed, and dropping data packets from the identified data packet flow subsequent to the predetermined number of data packets, until the packets that were not dropped have been delivered to the egress ports of the network.

Abstract: A network switch adaptive routing mechanism is disclosed along with an associated method of data routing. In particular, a mechanism is disclosed that enables adaptive routing selection within a crossbar switch.

Abstract: A data processing system comprises a first clock domain having a first clock rate, a second clock domain having a second clock rate, and a data path operable to transfer data items from the first clock domain to the second clock domain. The data path comprises a buffer having an input for receiving data items from the first clock domain, and an output port for transmitting data items to the second clock domain in a first-in first-out manner. The buffer has a first pointer for indication of a current first location of the buffer, and a second pointer for indication of a current second location of the buffer. The system further includes a read controller operable to define a read pattern for the buffer, to control output from the buffer in dependence upon such a read pattern, and to adjust such a read pattern in dependence upon a value of such a first pointer for the buffer.

Abstract: A method for controlling data packet routing through a switching element having a first plurality of input ports and a second plurality of output ports, the method comprising the steps of: detecting issuance of a first congestion indicator from an output port of the switching element, the first congestion indicator relating to a first routing request from a first input port of the switching element; allowing reassertion of the first routing request after a first time period; detecting issuance of a second congestion indicator from the output port of the switching element, the second congestion indicator relating to a second routing request from a second input port of the switching element; allowing reassertion of the second routing request after a second time period, wherein the first and second time periods are such that reassertions of the first and second connection requests occur substantially simultaneously. Also provided is a device for controlling such data packet routing.

Abstract: A technique is described for retrieving data from a hash table in an Ethernet bridge. The table has a plurality of columns, each of which has a hash function, thereby creating respective different hash key values.

Abstract: The present invention provides a multi-path network for use in a bridge, switch, router, hub or the like, the multi-path network including a plurality of network ports; a plurality of network elements; and a plurality of network links interconnecting the network elements and the network ports for transporting data packets, each network element including a fault monitor for detecting faults on the network links to which the network element is connected, a plurality of dynamically selectable output ports and output port selection mechanism and each network element being adapted to communicate the existence of a fault back to one or more other network elements via which network elements the faulty network link can be bypassed, and each network element being adapted to update the output port selection mechanism when communication of the existence of a fault is received so that only output ports which ensure the faulty network link is bypassed are dynamically selectable.

Abstract: The present invention provides a method of limiting the frequency of floods within a data network, the floods arising as a data frame is routed to an unknown destination, the method comprising the steps of: (a) receiving (42) on an ingress port a data frame intended for a destination station and containing a MAC address of that station; (b) checking (50) the destination MAC address with the contents of a MAC table; and thereby (c) determining (50, 54, 58, 62) whether the data frame is to be routed (56), discarded (60, 66) or flooded (52, 64) to all ports except the ingress port; and (d) respectively routing (56), discarding (60, 66) or flooding (52, 64) the data frame to all ports except the ingress port, as determined in Step (c).

Abstract: The present invention provides a multi-path network for use in a bridge, switch, router, hub or the like, comprising a plurality of network ports adapted for connection with one or more devices, each device having a different identifying address data; a plurality of network elements; and a plurality of network links interconnecting the network elements and connecting the network elements to the network ports, wherein the multi-path network further comprises separately addressable memory elements each adapted for storing device address data and the multi-path network is adapted to distribute a plurality of device address data amongst the plurality of memory elements.

Abstract: The present invention relates to a method of managing congestion in a multi-path network, the network having a plurality of network elements arranged in a plurality of switch stages and a plurality of network links interconnecting the network elements, the method comprising the steps of detecting congestion on a network link, the congested network link interconnecting the output port of a first network element with a first input port of a second network element in a subsequent switch stage; identifying an uncongested network link connected to a second input port of said second network element; and directing future data packets on a route across the multi-path network which includes the identified uncongested network link. Also provided is a multi-path network and an Ethernet bridge or router incorporating such a multi-path network.

Abstract: The present invention provides a method of preserving packet ordering in a multi-path network having a plurality of network elements interconnected by network links wherein for each data packet arriving at an egress port of the multi-path network, a delivery acknowledgement is issued by the egress port and is transmitted across the network following in reverse the path taken by the data packet being acknowledged, and wherein the state of each link in the path taken by the data packet being acknowledged is updated by the acknowledgement.