Extreme Networks, Inc.

International Business Machines Corporation

Olen L Stokes

Donald Bruce Grosser, Jr

Edward Joel Rovner

Sunil Praful Shah

Arnel Lim

LeRoy D Dickson

George J Laurer

Eric C Broockman

Claude Basso

Robert Thomas Cato

Paolo Scotton

Douglas H Dykeman

Cedell A Alexander

Lance Richardson

Charles M Pierce

Marianne Aubry

Norman J Woodland

Michael Osbourne

Douglas C Antonelli

Minh-Tri Do Khac

Patricia M Branscomb

Caralee P Koppel

Richard Ossowski

Justus W Gries

Sunil P Shah

Armel Lim

Embodiments disclosed herein provide redundant connectivity between an Ethernet Automatic Protection Switching (EAPS) access network and a Virtual Private LAN Service (VPLS) network. A first VPLS node is provided to function as an EAPS controller node. A second VPLS node is provided to function as an EAPS partner node. The first and second VPLS nodes are linked by a pseudowire and an EAPS shared-link. Additional EAPS nodes are also provided. The additional EAPS nodes are linked to each other and one of the additional EAPS nodes is designated as a master node. Links are also established between the VPLS nodes and the EAPS nodes such that one or more EAPS rings are formed. Each EAPS ring includes the shared-link between the first and second VPLS nodes. The EAPS rings are monitored to detect link failures. When a failure of the pseudowire shared-link between the first and second VPLS nodes is detected, all pseudowire links associated with the first VPLS node are disabled if any of the EAPS nodes has a path to both of the VPLS nodes. Otherwise, the existing pseudowire links associated with the first VPLS node are maintained.

Redundant ethernet automatic protection switching access to virtual private LAN services

Redundant Ethernet automatic protection switching access to virtual private LAN services

The subject mailer described herein includes methods, systems, and computer readable media for automatically selecting between Internet protocol switching modes on a per-module basis in a packet forwarding device. According to one aspect, a method may include determining capacities of hardware longest prefix matching (LPM) tables located on each input/output (I/O) module in a multi-module IP packet forward device. The number of routes currently stored in a software LPM table may be determined. If the software LPM table can be stored within the hardware LPM table for an I/O module, an LPM mode may be automatically selected for that I/O module. If the contents of software LPM table cannot be stored within the hardware LPM table for a particular I/O module, the I/O module may be automatically transitioned to operate in an Internet protocol forwarding database (IPFDB) mode.

Methods, systems, and computer readable media for automatically selecting between internet protocol switching modes on a per-module basis in a packet forwarding device

An indication of a host route to be added to a forwarding database table as an entry is received. The host route is added to a first hardware table or a second hardware table if a space is available in the second hardware table or in a first storage area of the first hardware table. The first hardware table has both a first storage area and a second storage area. If a space is not available in the second hardware table or the first storage area of the first hardware table, the first storage area of the first hardware table is automatically expanded to include unused space in the second storage area of the first hardware table. The host route is then added to a space in the expanded first storage area of the first hardware table.

Method and system for automatic expansion and contraction of IP host forwarding database

The subject matter described herein includes methods, systems, and computer program products for routing packets at a multi-mode layer 3 packet forwarding device. According to one aspect, the subject matter described herein includes operating a first of at least two modules in a host mode, and operating a second of at least two modules in a longest prefix matching (LPM) mode. Operating a module in a host mode includes populating a host table and an LPM table with entries corresponding to hosts and routing layer 3 packets received by the first module using the host and LPM tables. Operating a module in an LPM mode includes populating a host table with entries corresponding to hosts, populating an LPM table with entries corresponding to variable length Internet protocol (IP) addresses and next hop addresses, and routing layer 3 packets received by the second module using the host and LPM tables.

Methods, systems, and computer program products for routing packets at a multi-mode layer 3 packet forwarding device

Methods, systems, and computer program products for controlling updating of a layer 3 host table based on packet forwarding miss counts are disclosed. According to one method, layer 3 packets are routed using at least one of a layer 3 host table containing entries corresponding to remote hosts and a longest prefix matching table containing prefixes corresponding to remote hosts. For each layer 3 destination address for which a lookup in at least one table fails, a number of packets received within a time period are counted. Remote destination entries in the host table are replaced based on the counts.

Methods, systems, and computer program products for controlling updating of a layer 3 host table based on packet forwarding lookup miss counts

Address management methods and apparatus are provided for a node serving as peer group leader for a peer group of nodes in one level of the hierarchy of a PNNI hierarchical network, whereby the peer group leader represents the peer group to one or more neighboring nodes in the next level up of the hierarchy. The peer group leader has a memory () for storing peer group topology data (), comprising address data which is supplied to the peer group leader from nodes in the peer group and represents addresses for access by the network, and peer group leader topology data (), comprising address data which is supplied to said neighboring nodes by the peer group leader and represents addresses accessible via the peer group. The address management method comprises: checking whether addresses represented by said address data are accessible via the peer group; notifying said neighboring nodes of changes in the accessibility of addresses so identified; and updating said peer group leader topology data () in accordance with said changes.

Address management in PNNI hierarchical networks

When Internet Protocol (IP) packets or Layer-2 MAC Protocol packets are encapsulated in a MultiProtocol Label Switching (MPLS) packet, one or more labels are assigned to identify the routers of the MPLS network through which the packet has passed. From this information, the underlying protocol (e.g., IP, MAC) can be inferred. In one embodiment, the value assigned to the one or more labels is selected to identify the underlying protocol. In one embodiment, IP packets have label values in a first range and MAC packets have label values in a second range. When the MPLS-encapsulated packets are switched within a load sharing environment, the ranges of the label values indicate the underlying protocol of the packet being switched. Knowing the underlying protocol enables a hash function to be selected that will both preserve packet ordering and effectively load share traffic received from a higher-speed source link across multiple lower-speed links.

Load-sharing technique for distributing multi-protocol label switching protocol encapsulated flows across multiple physical links

A method for forming UPC or EAN bar code labels from scans of half labels or less than half labels requires that captured data be examined and classified as being either a first type of data configuration or a second type. A first type includes a given number of numeric characters delimited by both margin and center characters. A second type includes either a margin character or a center character and a given number of numeric characters. Labels are formed, where possible, by using appropriate first type data configurations. If labels cannot be formed using only first type configurations, second type configurations are examined to determine if they could represent different portions of the same region (left or right) of a label. If complementary second type configurations are found, they are merged to form a half label. The formed half label may be further merged with a complementary first type data configuration to form a complete label.

Bar code label identification circuit

A system is disclosed for preventing processing of duplicative coded label signals generated by a scanner lacking item detectors. The system establishes a variable lockout time as a function of operator performance. Any detected label candidate which duplicates a candidate received within the lockout time is assumed to be duplicative. Any transfer to the terminal is inhibited. Operator performance is tracked by measuring the inter-item arrival times for candidates actually transferred to the terminal. The inter-item arrival times are averaged over a given number of items. The average value is used to select a lockout time which is generally proportional to the average inter-item arrival time.

Method of inhibiting processing of duplicative coded label signals

Operating parameters for a multiple facet holographic disc scanner are adjusted on real time basis as a function of the actual diffraction efficiency of the facet region aligned with the impinging laser beam. The operating parameters are adjusted to achieve optimum signal levels independent of facet characteristics. Diffraction efficiency is inversely related to zero order beam power for a given level of input beam power. A photodetector measures the zero order beam power. The output of this photodetector is used to control video amplifier gain and/or semiconductor laser current.

Holographic scanner control based on monitored diffraction efficiency

An optical scanner in a retail store checkout stand includes a single item detector upstream of the scanner window. Output signals from the item detector and from symbol recognition logic are used to open and close a shutter in the beam path of the scanner laser. The shutter is opened and a first time out sequence is started when the beam path is interrupted. A second, short time out sequence is restarted each time a valid symbol is recognized. A third time out sequence of intermediate length supersedes the first time out sequence when the beam path is cleared. The laser shutter is closed and the symbol is transferred to a terminal or controller upon the completion of any active time out sequence or upon recognition of a predetermined number of identical symbols, whichever comes first.

Method for controlling the operation of an optical scanner

In decoding a UPC-type label, a partial decode and majority vote technique is employed to select final values for ambiguous characters (i.e., 1-7, 2-8) appearing in the label. During the partial decode phase, character-identifying values are established for every character but a common value is assigned to any ambiguous character in a given subset of such characters. An ambiguity-resolving value is additionally assigned to an ambiguous character each time it appears. Through algebraic summation of the ambiguity-resolving values for each character position occupied by an ambiguous character, the ambiguous character which appears a majority of times in that position is finally selected.

Growing community of inventors

Cary, NC, United States of America

Olen L Stokes