Lucent Technologies Inc.

Bell Telephone Laboratories

Warren Clifton Trested, Jr

Mark A Bordogna

Joseph Elide Landry

Philip Sidney Dietz

Jeffrey Robert Towne

Don I Falkenstein

Michael L Steinberger

Larry P Lewis

Blaine A McKenzie

An integrated network element includes the functions of multiple Ring add-drop-multiplexers and a digital cross connect. A user may provision cross connections between input and output path-level units of bandwidth referred to herein as 'logical tributaries.' Each port within the integrated network element may be combined with one or more other ports to form a user-provisioned association of optical interface ports that is used for line protection (or SDH multiplex section protection) in a particular type of network configuration, referred to as a 'port protection group'. Each port within a port protection group may have a plurality of logical tributaries associated with it. By allowing a user to provision cross connections between logical tributaries, rather than directly between ports, an integrated network element in accordance with the principles of the present invention permits a user to provision working and protection paths from any port to any other port in the integrated network element without requiring the user to know the details, such as switching status, whether a port associated with a particular port tributary is a member of a port protection group, what type of port protection group a port tributary is a member of, the state of protection switching, or other such details. A user interface allows a user to provision the behavior and report the results of path-level signal monitoring (for faults and performance) and of path-level protection switching.

Integrated network element

A unique trace word is assigned to each incoming signal routed by a sliced switch fabric having two or more parallel switches. The unique trace word is encoded into each incoming signal following an overall format that ensures that each sliced trace word (i.e., the subset of bits in the overall format routed by each parallel switch) also uniquely identifies each incoming signal. In this way, the present invention ensures that the switch configuration of each and every parallel switch can always be verified. As such, any improper switch configuration can be detected, including those misconfigurations in which all but one of the parallel switches are correctly configured as well as those misconfigurations in which all of the parallel switches are identically, but incorrectly configured. In a preferred embodiment, the overall format is defined in terms of a table, in which each column comprises all of the bits of the unique trace word and the bits are shifted cyclically between pairs of columns to reduce the number of rows of the table that need to be processed before all of the bits in the unique trace word are available in the outgoing signal transmitted from the sliced switch fabric.

Trace format for a sliced switch fabric

Distributed switch fabrics can support multiple switching functions while meeting established performance requirements by using a control architecture based on multiple layers of signal status carried within signals transported through the distributed switch fabrics. More specifically, a method and apparatus is provided for controlling the selection of signals through distributed switch fabrics by deriving signal status information for the signals at any point along a transmission path and embedding the signal status information in each of the signals using multiple signal status layers. Each of the signals carries its respective signal status information as it propagates along the transmission path, so that the embedded signal status information can be selectively extracted from any of the multiple signal status layers to facilitate a selection decision at any of the distributed switch fabrics. The multiple layers of signal status can be used to provide a cumulative signal status of a particular signal as it propagates along the transmission path or the multiple layers can be used to support various combinations of status control, such as each layer being used to track a different level or type of status for the signal.

Control architecture using a multi-layer embedded signal status protocol

A simple, elementary switch fabric is provided for switching individual signals as a composite group based on group signal status that is embedded and carried within each of the individual signals in the group. In general, a group signal status is derived for a group based on the signal status of each of the individual signals within that group. This group signal status is then individually encoded and embedded in each of the individual signals in the group. The embedded group signal status can be extracted and decoded at any point within the transmission path, as necessary, to facilitate appropriate switching decisions. Although each individual signal is switched independently by the elementary switch fabric, the individual signals are effectively switched as a composite group because the switching decision for each individual signal in the group is based on the same group signal status. That is, individual signals in a particular group will either be selected or rejected together as a single, composite group.

Method and apparatus for switching signals using an embedded group signal status

A system for providing segmented control of a single, homogeneous routing structure, such as a switch fabric, includes application control elements that are each responsive to embedded signal status information for each of the input signals to the switch fabric. Within each of the application control elements, a configurable arrangement of selectors and control logic is used to provide domain segmented control of each of the separate switching functions for a particular application. Each application control element performs an application specific address resolution function to resolve a single address of one of the input signals based on the embedded signal status of each of the input signals. This single address is provided to the switch fabric so that the corresponding input signal can be selected at the switch fabric output. Because embedded signal status is provided locally at each selection point within the application control element, the control functions for each of the separate switching functions are decoupled, and, as a result, each of the separate switching functions can be independently controlled as a separate domain within the application control element. The single, homogeneous switch fabric simultaneously supports multiple applications in parallel because each of the application control elements is used to control a separate output from the switch fabric. Because of the one for one association between application control elements and switch fabric outputs, the switch fabric is effectively 'channelized' whereby each channel of the switch fabric supports a separate application.

Control architecture for a homogeneous routing structure

A network element with a centralized switch fabric is able to support multiple switching functions while meeting established performance requirements by using a control system based on an embedded signal status protocol. Generally, each input signal within a transmission path is monitored to derive signal status information, which is then individually encoded and embedded within the input signal. The embedded signal status can be decoded and provided as input to control logic for processing at any point within the transmission path, as necessary. In the case of a centralized switch fabric, the control logic resolves an address of a single input signal based on the embedded signal status and provides this resolved address to the switch fabric so that the appropriate input signal can be selected. In the present invention, the control logic may be configured to support any given application, e.g., 'path-in-line' protection switching, whereby each configuration of control logic constitutes an application control set that supports the performance requirements of that given application.

Control architecture using an embedded signal status protocol

An errorless line protection switching system utilizes a variable delay (29) in the spare channel (21-24, 26-29, 31-33) adjusted to provide data signal alignment with an impaired regular channel before substituting the spare channel for the regular channel. This switching system is able to provide bit error free channel substitution between the spare and any regular channel in a digital radio system by virtue of the data signal alignment capability. Data signal alignment is provided by first aligning clocking signals in fine incremental steps with each clocking signal derived from one of the two channels undergoing the substitution. Data signal alignment is then provided by shifting the spare channel in full bit positions until data alignment is indicated by a detector (119). Data signal alignment is also utilized to restore service to a regular channel so the spare channel may be removed from service.

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E. Hampstead, NH, United States of America

Warren Clifton Trested, Jr