3com Corporation

3 Com Corporation

Spinel Ektronix LLC

Congruency Inc.

Opher Yaron

Zvika Bronstein

Ilan Shimony

Golan Schzukin

Yuri Poddobny

Gennady Dosovitsky

Alon Hurwitz

Peter Si-Sheng Wang

Amit Lewin

Lior Katzri

Offer Pazy

Amit Levin

Tal Weiss

An apparatus for and method of encapsulating Ethernet frame data in Very high speed Digital Subscriber Line (VDSL) frames. The VDSL frames are transmitted over a point to point VDSL link where they are subsequently extracted and forwarded as standard Ethernet frames. The VDSL facility transport system comprises an Ethernet to VDSL Consumer Premises Equipment (CPE) coupled to a DSL Access Multiplexor (DSLAM) over a VDSL transport facility. The Ethernet to VDSL CPE functions to receive a 10BaseT Ethernet signal and encapsulate the Ethernet frame into a VDSL frame for transmission over the VDSL facility. The DSLAM is adapted to receive VDSL frames, extract Ethernet frames therefrom and generate and output a standard Ethernet signal. Ethernet frames are encapsulated within VDSL frames and transmitted on the wire pair without regard to the state of the SOC signals. This overcomes the problems associated with syncing the transmission of the Ethernet data with the SOC signals. The present invention also provides a method of providing the receiving station an indication of the start of a VDSL frame. A preamble having certain desirable characteristics such as good autocorrelation properties, is used by the receiving station to identify the start of a VDSL frame. To further ensure that a detected start of frame is valid, the length field of the VDSL frame is examined for a legal length value.

System for encapsulating Ethernet frames over very high speed digital subscriber lines

A forwarding table comprising a combination of a hash table and a content addressable memory (CAM). The forwarding table combines a one way hash table and a small CAM to perform the forwarding information retrieval function. The CAM is used when an address cannot be found in the hash table. When MAC addresses are being added to the forwarding table, they are first tried in the hash table. The address is applied to the hash function and a resulting index input to the hash table. If a hit occurs, it indicates that an entry at that index already exists and a location in the CAM is then allocated for that address. As long as the CAM does not become full, a 100% hit rate is guaranteed. During retrieval, the hash table or the CAM forms the forwarding information output to the next processing stage. If an entry is not found in the hash table, it will typically be found in the CAM. If no entry is found in either, the received frame is flooded to all the ports of the network device.

Forwarding table incorporating hash table and content addressable memory

An apparatus for and a method of extending the ATM Forum LAN Emulation standard to support 802.1Q VLAN tagging with Independent VLAN Learning. A standard LEC entity is modified to perform the VLAN tagging method that supports Independent VLAN Learning. Since the LES may also respond to LE_ARP messages, it is optionally modified to perform the VLAN tagging method of the invention so as to provide support for 802.1Q Independent VLAN Learning. Support for 802.1Q Independent VLAN Learning is provided by adding a VLAN-ID TLV to LAN Emulation control messages such as LE_ARP and LE_REGISTER messages. The TLV added comprises the VLAN Tag Header information that is normally carried by the Ethernet frame in 802.1Q networks.

Apparatus for and method for supporting 802.1Q VLAN tagging with independent VLAN learning in LAN emulation networks

An apparatus and associated method for performing flow switching (tag switching) in a frame switching environment. The flow switching apparatus provides a mechanism whereby flows are identified and tags assigned to them. The identification and assignment of tags to flows is made Independently of other network entities and does not require communications with any other entities within the box itself or other entities in the network. The forwarding decisions are calculated once and stored in a cache or a look up table which can be accessed very quickly. The tag is used as an index into the cache or LUT such that if an entry is found in the cache or LUT for that particular tag, the forwarding decision does not have to be made again. This serves to greatly reduce the time to obtain a forwarding decision which is used by the switching fabric in steering the input frame to the appropriate output port(s). Multiple queues are used along with the cache to facilitate the forwarding of the frames. Frames that generate a cache miss are stored in a slow queue to await software processing. Once a forwarding decision is made, all the frames in the queue are switched at once. Frames that generate a hit are placed on a fast queue for expedited processing.

Apparatus for and method of flow switching in a data communications network

A proxy MPOA client in a VLAN that is otherwise populated by legacy LECs such that the MPOA services for these LECs are provided centrally by the proxy MPC. A standard MPC enabled edge device is adapted to provide MPC services to legacy LECs that are not MPOA aware. Such an edge device provides MPOA services to legacy LECs located in other edge devices connected to the ATM cloud. The proxy MPC is configured to have at least two LECs: one residing on a legacy ELAN and another residing on an MPOA ELAN. Traffic from the legacy LEC arriving from the legacy ELAN is forwarded to an Ethernet port that is looped back to a second Ethernet port on the proxy MPC edge device. Upon ingress at the second Ethernet port, the traffic is treated as if it arrived from a regular port and provided with MPC services. The loopback may be implemented either internally or externally via one or more cables. In addition, an internal bridge is configured to steer the Ethernet traffic to the first Ethernet port for loopback to the second Ethernet port. Upon initial flow detection, the proxy MPC establishes a shortcut utilizing the MPOA Server (MPS). Once the shortcut is established, traffic is forwarded from the LEC on the MPOA side in the proxy MPC to the destination via the shortcut.

Proxy MPC for providing MPOA services to legacy lane clients in an asynchronous transfer mode network

An apparatus for and method of encapsulating Ethernet frame data in Very high speed Digital Subscriber Line (VDSL) frames. The VDSL frames are transmitted over a point to point VDSL link where they are subsequently extracted and forwarded as standard Ethernet frames. The VDSL facility transport system comprises an Ethernet to VDSL Consumer Premises Equipment (CPE) coupled to a DSL Access Multiplexer (DSLAM) over a VDSL transport facility. The Ethernet to VDSL CPE functions to receive a 10BaseT Ethernet signal and encapsulate the Ethernet frame into a VDSL frame for transmission over the VDSL facility. The DSLAM is adapted to receive VDSL frames, extract Ethernet frames therefrom and output a standard Ethernet signal. Ethernet frames are encapsulated within VDSL frames and transmitted on the wire pair without regard to the state of the SOC signals thus overcoming the problems associated with syncing the transmission of the Ethernet data with the SOC signals. The present invention also provides a method of providing the receiving station an indication of the start of a VDSL frame. A preamble having certain desirable characteristics is used by the receiving station to identify the start of a VDSL frame. To further ensure that a detected start of frame is valid, the length field of the VDSL frame is examined for a legal length value.

A device, system and method for providing power in a secure manner to a network device connected to a network, such as an Ethernet network for example. The device is optionally implemented as an intelligent power supply, which is able to interrogate the network device before power is supplied, in order to determine the electrical capabilities of the device and/or whether the device is authorized to be connected to the network. Such an intelligent power supply preferably communicates with a low power communication device at each network device, which supplies the necessary information upon request.

Device, system and method for secure

An apparatus for and a method of compressing the forwarding decision for a frame within a network device. A forwarding decision is compressed yielding a forwarding pointer that occupies far less memory space than the corresponding output port vector. The compressed forwarding pointers are stored in a forwarding table that is accessed using a hash function. A forwarding CAM is used to resolve conflicts in the hash table. The output port vectors are stored in an output port vector table that comprises a relatively small number of possible combinations of the port vector. A forwarding decision is made for each received frame by a forwarding processor in the device. The forwarding decision is represented by a compressed forwarding pointer that is stored in a table and associated with the received frame. At some later point in time, the frame is output to one or more destination ports in accordance with a corresponding output port vector. At this time, the compressed forwarding decision is expanded to an output port vector using the relatively small port vector table. In this fashion, large memories to store the actual output port vector are not needed since only a relatively short pointer to the port vector is stored rather than the port vector itself.

Compression of forwarding decisions in a network device

An enhanced cells-in-frames (CIF) network system for connecting a local-area-network (LAN) to an ATM network consists of CIF end-stations and an enhanced CIF attachment-device attached to a LAN segment. The enhanced CIF attachment-device in addition to performing its conventional functions, recognizes connection requests between local CIF end-stations and sets up short-cut forwarding between such end stations allowing them to transfer CIF frames directly over the Ethernet. In a conventional system such local traffic would broken up into a plurality of cells and sent over an ATM network.

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Tel Aviv, Israel

Opher Yaron