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Signalling Gateway

Description: OpenSS7 Application Design Documentation.

The Signalling Gateway product provides a signalling gateway for SS7/SIGTRAN applications.

A PDF version of this document is available here.

OpenSS7 Signalling Gateway Platform

OpenSS7 Signalling Gateway Platform High-Level Design

About This Manual

This is Edition 7.20141001, last updated 2014-10-25, of The OpenSS7 Signalling Gateway Platform High-Level Design, for Version 1.1 release 7.20141001 of the OpenSS7 package.


Executive Overview

This document provides a High-Level Design for the OpenSS7 Signalling Gateway Platform. The initial and primary purpose of this equipment is to provide connectivity between a legacy SS7 network and a SIGTRAN network. Because the solution attempts to avoid excessive costs associated with long- and short-haul SS7 TDM circuits, the platform benefits from using low cost commodity hardware and open source software.

The OpenSS7 Project

The OpenSS7 Project is an open source software project that has developed many protocol components within the SS7, SIGTRAN, ISDN and VoIP protocol stacks. Intellectual property rights for the OpenSS7 Project are held by OpenSS7 Corporation. All OpenSS7 Project software is eventually licensed under the GNU Affero General Public License Version 3. OpenSS7 Corporation also provides commercial licensing of OpenSS7 Project software under terms less restrictive than the AGPL.

Signalling Gateway (SG) Platform

OpenSS7 can provide Signalling Gateway Platform capabilities in a high-performance, low-cost, small-footprint platform leveraging the GNU/Linux operating system distributions and tools, and utilizing low-cost commodity hardware.

For detail on platform applications, see Application Architecture, Network Architecture, Optional Application Support, and Optional Network Support.

Open Source Software

The OpenSS7 Project leverages the widespread use of GNU/Linux operation systems, distributions, and FSF tools such as ‘autoconf’ and open source software such as RPM. For example, this document was formatted for PDF, HTML, info and plain text using the GNU texinfo system, ‘autoconf’, and the TeX formatting system.

The open source model avoids proprietary lock-in and permits in-house or outsourced development. All source code is available for use and modification by the end customer. All build tools, documentation and associated resources are generally available. The availability of the source code and complete documentation eases problem resolution and can offer upgrades and fixes even in advance of client problem reports.

For details on software solutions, see Protocol Architecture, Software Architecture, Optional Protocol Support, and Optional Software Support.

Commodity Hardware

By best utilizing commodity PC or standardized CompactPCI and AdvancedTCA hardware, OpenSS7 makes available the highest performance platforms available on the market at back-to-school prices. When carrier-grade is not essential, 3GHz Pentium or Xeon class servers in hardened rack mount chassis can be used at a fraction of the cost, and yet outperform, other solutions. Where carrier-grade is necessary, embedded Linux on standardized CompactPCI and AdvanceTCA NEBS compliant chassis make for a higher cost, but more reliable alternative.

For details on hardware solutions, see Platform Architecture, Hardware Architecture, and Optional Hardware Support.

Integrated Management

Utilizing open source management tools, such as net-snmp and OSIMIS, OpenSS7 protocol stacks provide integrated management support for SNMPv2c, SNMPv3, or CMISE/CMIP. The entire platform, from alarms to provisioning, can be provided using integrated SNMP agents.

For details on management solutions, see Platform Architecture, Management Architecture, and Optional Management Support.

Rapid Development

The OpenSS7 Project has already developed protocol components completing the SS7 and SIGTRAN signalling stacks including MTP Level 2 and Level 3, ISUP, SCCP, TCAP; and SCTP, M2PA, M2UA, M3UA, SUA and TUA. Development of a Signalling Gateway Platform to meet small to large scale deployment requirement needs only customization of the platform for specific needs.

For details on scheduling, see Logistics.

An Evolving Solution

The OpenSS7 Project is evolving to support more protocol stacks including ISDN and VoIP. Support for an ever expanding capability is demonstrated by the additional options available as described in Optional Application Support, Optional Network Support, Optional Protocol Support, Optional Software Support, and Optional Hardware Support.

Conclusions

In summary, a Signalling Gateway Platform for small and large scale deployments is an excellent application of the OpenSS7 SS7 and SIGTRAN stacks and can be provided at an affordable price on short time-lines, while offering an evolution path for future deployment applications.





Brian Bidulock The OpenSS7 Project


Preface

Document Information

Abstract

This document provides a High-Level Design for the OpenSS7 Signalling Gateway Platform.

Objective

The objective of this document is to provide a High-Level Design for the development of a low cost, high-performance, OpenSS7 Signalling Gateway Platform using OpenSS7 protocol components, software, and compatible systems and hardware.

Intent

The intent of this document is to act as a High-Level Design for a project for an High-Level Design. As a High-Level Design, this document discusses components and systems which are not necessarily complete. OpenSS7 Corporation is under no obligation to provide any software, system or feature listed herein.

Audience

This document is intended for a technical audience. The reader should be familiar with most ETSI, ITU-T and ANSI, Signalling System No. 7 recommendations, as well as IETF drafts and RFCs for SIGTRAN protocols. Because much of the focus of a Signalling Gateway Platform is on SS7 signalling, the reader should be familiar with ITU-T, ETSI and ANSI standards regarding Signalling System No. 7 as applied to Signalling Transfer Points.

Revisions

Take care that you are working with a current version of this document: you will not be notified of updates. To ensure that you are working with a current version, contact the Author, or check The OpenSS7 Project website for a current version.

Version Control

$Log: sg.texi,v $
Revision 1.1.2.4  2011-08-07 11:14:29  brian
- mostly mandriva and ubuntu build updates

Revision 1.1.2.3  2011-07-27 07:52:16  brian
- work to support Mageia/Mandriva compressed kernel modules and URPMI repo

Revision 1.1.2.2  2011-02-07 02:21:36  brian
- updated manuals

Revision 1.1.2.1  2009-06-21 10:48:29  brian
- added files to new distro

ISO 9000 Compliance

Only the TeX, texinfo, or roff source for this document is controlled. An opaque (printed or postscript) version of this document is an UNCONTROLLED VERSION.

Disclaimer

OpenSS7 Corporation disclaims all warranties with regard to this documentation including all implied warranties of merchantability, fitness for a particular purpose, non-infringement, or title; that the contents of the document are suitable for any purpose, or that the implementation of such contents will not infringe on any third party patents, copyrights, trademarks or other rights.. In no event shall OpenSS7 Corporation be liable for any direct, indirect, special or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortious action, arising out of or in connection with any use of this document or the performance or implementation of the contents thereof.

OpenSS7 Corporation reserves the right to revise this software and documentation for any reason, including but not limited to, conformity with standards promulgated by various agencies, utilization of advances in the state of the technical arts, or the reflection of changes in the design of any techniques, or procedures embodied, described, or referred to herein. OpenSS7 Corporation is under no obligation to provide any feature listed herein.

Document Organization

This document is organized as follows:

Introduction

Introduction to the OpenSS7 Signalling Gateway Platform application.

Application Architecture

The application requirements and architecture.

Network Architecture

The network architecture for the application.

Reference Architecture

The reference architecture for the application.

System Architecture

The architecture of the OpenSS7 Signalling Gateway Platform system.

Platform Architecture

The architecture of the OpenSS7 Signalling Gateway Platform platform.

Protocol Architecture

The protocol architecture supporting the application.

Software Architecture

The software architecture supporting the protocol stack and application.

Hardware Architecture

The hardware architecture supporting the protocol stack and application.

Management Architecture

The management architecture supporting the system and application.

Logistics

Project logistics for completion of the OpenSS7 Signalling Gateway Platform application.

Optional Application Support

Additional application support not directly contributing to the current objective.

Optional Network Support

Additional network interface support not directly contributing to the current objective.

Optional Protocol Support

Additional protocol component support not directly contributing to the current objective.

Optional Software Support

Additional software support not directly contributing to the current objective.

Optional Hardware Support

Additional hardware support not directly contributing to the current objective.

Optional Management Support

Additional managment component support not directly contributing to the current objective.

Programmatic Interfaces

Programmatic interfaces to selected protocol components.

Platform Sizing

Detailed platform sizing considerations.

Index

Index of concepts, manual pages, etc.


1 Introduction

This document provides a High-Level Design for a platform to provide the OpenSS7 Signalling Gateway Platform capabilities. The primary driver for the OpenSS7 Signalling Gateway Platform is to provide a system that avoids the use of expensive graded long haul SS7 facilities. The document provides a high-level design and proposal for a production system to provide this capability.

The proposal utilizes, where possible, existing OpenSS7 SS7 and SIGTRAN stack components and provides a develoment plan for components that are specific to the OpenSS7 Signalling Gateway Platform requirements.

This document discusses the resulting software configuration that will be put in place on the production system, the platform configuration for the production system, and a network configuration for deployment. Also discussed is an overview of the project management logistics for successful completion over the course of this development project.

It is intended that this document be a “living” document, that is updated over the course of this development project.


1.1 The OpenSS7 Signalling Gateway

This project provides an OpenSS7 Signalling Gateway Platform that translates signalling traffic between the traditional SS7 signalling network and a SIGTRAN signalling network. The gateway also provides a basis for geographic and functional redundancy of systems within the SIGTRAN signalling network.


1.2 Project Drivers

The lead purpose of the OpenSS7 Signalling Gateway Platform is to provide a flexible and redundant Signalling Gateway front-end solution for the OpenSS7 VoIP Switch.


1.3 Scope

Because the focus on low cost, high performance, and production stability, the OpenSS7 Signalling Gateway Platform is constructed using commodity computing platforms and PCI based hardware cards, but using hardenned NEBS-3/ETSI compliant chasses in an active/standby failover configuration. This will result in a cost-effective carrier grade system for mid- to low deployment cost.


1.3.1 Phases

The longer term project is broken into the following phases:

Phase 1

The initial phase of the project is intended to provide the capabilities of the OpenSS7 Signalling Gateway Platform operation for the deployment platform.

Phase 2

The second phase of the project is intended on performing SS7 signalling interoperability testing for live deployment of the signalling gateway production platform.

Phase 3

The third phase of the project is to integrate the deployment platform with the OpenSS7 VoIP Switch using the Internet Protocol suite.

Phase 4

The fourth phase of the project is to perform interoperability testing and a field trial of the deployment platform.

Phase 5

The fifth phase of the project is to complete management system integration for remote monitoring and provisioning for production service.


1.3.2 Gates

Each phase of the project consists of seven gates. The seven gates are defined as follows:

Gate 0 — Concept

Gate 0 is passed when the initial concept has been elucidated and work is begun on a High-Level Design. This is an internal OpenSS7 gate.

Gate 1 — High Level Design

Gate 1 is passed when the high-level design has been reviewed to the satisfaction of the consumers of the project. This is an external review gate. OpenSS7 internally passes this gate once the High-Level Design has been published and work is begun on a detailed design.1

Gate 2 — Detailed Design

Gate 2 is passed when the detailed design has been reviewed to the satisfaction of the consumers of the project and the developers on the project. This is an external as well as an internal review gate. OpenSS7 passes this gate once the Detailed Design has been published and work has begun on development and implementation of the design.2 Passing this gate moves from the design stage to the development stage of the project.

Gate 3 — Deployment and Implementation

Gate 3 is passed when the software and systems development and implementation to the detailed design is complete and testing has begun. This is an internal review gate. OpenSS7 internally passes this gate when software is code complete and hardware has been installed for testing.

Gate 4 — System Test

Gate 4 is passed once the product implementation meets all internal ad hoc and formal conformance test suites and internal testing is complete. This is an internal review gate. OpenSS7 passes this gate internally once conformance testing is complete. Passing this gate moves from the development stage to the support stage of the project.

Gate 5 — Acceptance Test

Gate 5 is passed once the product implementation has passed external Gamma client acceptance testing. This is an external review gate. OpenSS7 passes this gate internally once participation in external acceptance testing is complete.

Gate 6 — Project Complete

Gate 6 is passed once all support obligations for the product implementation have been discharged. This is an internal review gate. OpenSS7 passes this gate once support agreements have terminated.

For more details on Gate scheduling for Phase 1, 2 and 3 of the project, see Schedule.


2 Application Architecture

The OpenSS7 Signalling Gateway Platform is intended to provide high performance, low cost Signalling Gateway services between traditional SS7 and SIGTRAN networks.


2.1 Application Background


2.2 Application Objectives


2.3 Application Requirements

Application requirements have been broken into 5 phases using the timeboxing approach.

2.3.1 Phase 1 Requirements

Phase 1 requirements provide an OpenSS7 Signalling Gateway Platform capability that will connect an existing SS7 network to application servers using M3UA.

2.3.2 Phase 2 Requirements

Phase 2 requirements provide

2.3.3 Phase 3 Requirements

Phase 3 requirements provide

2.3.4 Phase 4 Requirements

Phase 4 requirements provide

2.3.5 Phase 5 Requirements

Phase 5 requirements provide


2.4 Solution Architecture

Although the functions of Media Gateway Controller, Media Gateway and Signalling Gateway have been decomposed, and in the past these functional groups have been implemented on separate physical platforms, modern compute capacity and densities permit these functions to be integrated into a single physical platform without limitation. Open standard interfaces are utilized internal to the platform to permit a decomposed model to be split out and to permit ETSI Tiphon Version 4 compatibility as well as Multi-Services Forum Version 2 compatibility.

2.4.1 OpenSS7 Signalling Gateway Platform for Deployment

In light of the foregoing, the solution architecture takes the form of an integrated signalling gateway capable of providing a number of functional groups in the traditional models. The OpenSS7 Signalling Gateway Platform integrates the following functional groups while still permitting standard interfaces to be exposed for maximum deployment flexibility:


2.5 Message Flows

This section provides some illustrative application call flows:3


3 Network Architecture

Figure 3.1 illustrates the network configuration of the OpenSS7 Signalling Gateway Platform in a typical deployment scenario. The SG platform is positioned and attached to switching equipment with A-Links, STPs with B/D-Links and Softswitches with M3UA.

Network Architecture

Figure 3.1. Network Architecture

The device is attached to STPs (Signalling Transfer Points) in the SS7 network via V401P-SS7 or other OpenSS7 SS7 link cards4 terminating SS7 B/D-Links, either 24 channels per span (T1), 56kbps or 64kbps ANSI T1.111.3 links, or 31 channels per span (E1), 64kbps Q.703 links, or full span ANSI T1.111.3 Annex B 1.544Mbps or Q.703 Annex B 2.048Mbps high-speed links, or via a signalling gateway device terminating SS7 level 2, 3 or 4 and transporting M3UA back-haul signalling to the load device over SCTP (Stream Control Transmission Protocol).

On the IP network side of the device, the platform is connected on an internal LAN with multiple Ethernet segments and IP subnetworks. ISUP signalling originating at a Service Switching Point (SSP) within the SS7 network are accepted and responded to by MGC within the IP network. Signalling lis converted from traditional TDM SS7 to SIGTRAN over the IP network via the Signalling Gateway.

From the viewpoint of the SS7 or SIGTRAN network, the platform acts as a Signalling Gateway for the purposes of passing ISUP and LNP messages between the MGC and the remotely attached SSPs and SCPs.

From the SS7 network, the SG platforms appear to be STPs and are connected with B/D-Links to an adjacent STP pair.5

From the IP network, the SG platforms appear in the SG as STP configuration for SIGTRAN. Although MGC’s are shown within the IP network as being provided SS7 connectivity by the SG platforms, any SIGTRAN equipped SS7 user application may also be supported by this configuration.


4 Reference Architecture


5 System Architecture

This section details the solution system architecture. The solution system architecture consists of the computing platform and it placement within the locale installation environment.

The solution system has the following requirements:

  • — 19" rack.
  • — -48 VDC electrical power.
  • — CO cooling.
  • — Bantam to RJ-48c patch pannel.
System Architecture

Figure 4.1. System Architecture


6 Platform Architecture

This section details the platform architecture. The solution platform architecture consists of the computing platform and associated hardware, interfaces and peripherals.

Figure 5.1 illustrates the solution platform rack configuration.

Rack Mount Components

Figure 5.1. Rack Mount Components

The solution platform consists of the following:

  • — Two hardened PC (2U) chassis per system.
  • — Two GigE (1000baseT) RJ-48c Layer 2 Ethernet Switches.
  • — Two 1-1 DSX 14 T1 patch pannels.

6.1 Platform Capacity

The PC chasses is equipped with the following:6

  • – 2 x 3.2GHz Xeon class E7520 based Motherboard.
  • – 2 x 100MHz PCI-X 2.1 bus.
  • – 4G DDR memory.
  • – 2 x Ultra320 SCSI hard drives.
  • – 2 X GigE Ethernet NICs.
  • – 3 x V401PT Quad T1 interface cards.

7 Protocol Architecture

Figure 6.1 illustrates the protocol configuration of the OpenSS7 Signalling Gateway Platform system. The protocol stack uses the following OpenSS7 stack components:

Protocol Architecture

Figure 6.1. Protocol Architecture


7.1 Protocol Components

The following Protocol Components are provided as part of the OpenSS7 SS7 and SIGTRAN stacks:


7.1.1 SS7/SIGTRAN Stack Manager


7.1.2 SCCP User Adaptation Layer (SUA) Driver

The SUA driver provides the SG with the ability to act as an SUA SG (Signalling Gateway) in conjunction with an SUA AS (Application Server). In this project, the SG function is performed by the OpenSS7 Signalling Gateway Platform. The SUA driver accepts the trasnport of SCCP to SCCP-User interface form the SG to the AS. The SUA driver links SCTP driver streams underneath it to provide the transport services for exporting the MTP-User interface. The SUA driver provides the same interface to its users as the OpenSS7 SCCP.

The SUA driver is a STREAMS driver that runs int he Linux kernel for maximum performance.

This is an existing OpenSS7 SIGTRAN stack component: for documentation, see: sua(4). Phase 1 activities for SUA include integration testing with the SG components.


7.1.3 Signalling Connection Control Part (SCCP) Driver

The Signalling Connection Control Part driver performs the essential transport functions of the SS7 signalling stack. Message Transfer Part or MTP3 User Adaptation Layer streams are linked under the driver and the driver provides the functions of a SCCP endpoint or relay with full global title translations. Signalling Connection Control Part streams bound to TCAP SCCP-SAPs are linked under the TCAP driver to form a complete SS7 stack in support of call transactions.

Signalling Connection Control Part (SCCP) Module

Figure 6.1b. Signalling Connection Control Part (SCCP) Module

The SCCP driver supports all CCITT/ITU-T versions (Blue Book forward), ETSI and ANSI versions (1992 forward), including both connectionless and connection-oriented protocol classes 0 through 3. The SCCP driver provides an extended NPI Revision 2.0 interface to its users and accepts an NPI Version 2.0 (Connectionless) MTP interface from beneath or a specialized OpenSS7 MTPI interface. In addition, a TPI Revision 2.0 user interface supporting an X/Open XNS 5.2 XTI library interface is provided.

The SCCP driver also provide GTT streams for servicing Global Title Translations requests. These streams can be used by a user-space program for servicing GTT requests from a local or remote database, or can have specialized STREAMS modules pushed to perform rule-based GTT in the operating system kernel.

The SCCP driver is a STREAMS driver that runs in the Linux kernel for maximum performance.

The Signalling Connection Control Part (SCCP) STREAMS module is responsible for providing SCCP services on top of a Message Transfer Part (MTP) Level 3 (MTP3) or MTP3-User Adaptation Layer (M3UA) stream. In addition, it is possible to use an ISO/OSI connectionless Network Service Provider to provide the network services to SCCP.

The OpenSS7 SCCP component has message encoding and decoding for ITU-T/ETSI and ANSI SCCP. Interfaces provided to SCCP users include an XTI/OSI capable TPI Revision 2.0 interface, an NPI Revision 2.0 interface, and an SCCP-specific interface.

The OpenSS7 SCCP module supports all Protocol Classes.

This is an existing OpenSS7 SS7 stack component; for documentation, see: sccp(4). Phase 1 activities for SCCP include integration testing with the SG components.


7.1.3.1 Global Title Translations (GTT)

The Signalling Connection Control Part (SCCP) Global Title Translations (GTT) module is responsible for responding to SCCP-GTT translations originating from the SCCP module beneath and is responsible for generating outgoing SCCP-GTT translations to the SCCP module beneath. To perform its function, the SCCP-GTT indexes all information based on the SCCP Address, including dynamic (state) and provisioned (result) information. For performance in both a testing and production environment, the module provides three levels of database partitioning and caching:

Rules

Rules can be provided that are used to determine provisioned information based on components of the index (GT). These rules can be used to generate a rather large simulated database without maintaining or accessing large database record areas. The rule base provides a simulated partitioned database. Each rule refers to a template or partial template of provisioned data.

Templates

Templates can be provided that specify a profile of provisioned information for a class of indexes (GT). Templates provide a compact local in-kernel cache of templates. Indexes reference templates rather than complete records.

Records

Records can be provided that specify the provisioned information for the specific index (GT). Records provide a local in-kernel cache of specified records. Records are unique for each index.

Translations

The application can be queried by indicating the index (GT) and the module awaits a response containing the provisioned information. Translations provide access to an external database or algorithm.

For the High Performance GSM/UMTS GPRS HLR application, messages can be routed on Translation Type or on the basis of the Subsystem Number alone, resulting in a simple rule provided to the SCCP-GTT. If the High Performance GSM/UMTS GPRS HLR application is not expected to perform in any other role, the High Performance GSM/UMTS GPRS HLR application can bind as the "Default Destination" for all SCCP Unitdata messages, obviating the need for GTT.

This is an existing OpenSS7 SS7 stack component; for documentation, see: sccp(4). Phase 1 activities for SCCP include integration testing with the SG components.


7.1.4 MTP Level 3 User Adaptation Layer (M3UA) Driver

The M3UA driver provides the SG with the ability to act as an M3UA SG (Signalling Gateway) in conjunction with an M3UA AS (Application Server). In this project, the SG function is performed by the OpenSS7 Signalling Gateway Platform. The M3UA driver accepts the transport of the MTP to MTP-User interface from the SG to the AS. The M3UA driver links SCTP driver streams underneath it to provide the transport services for exporting the MTP-User interface. The M3UA driver provides the same interface to its users as the OpenSS7 MTP.

The M3UA driver is a STREAMS driver that runs in the Linux kernel for maximum performance.

This is an existing OpenSS7 SIGTRAN stack component; for documentation, see: m3ua(4). Phase 1 activities for M3UA include integration testing with the SG components.


7.1.5 Message Transfer Part (MTP) Driver

The message transfer part driver performs the essential network functions of the SS7 signalling stack. M2UA streams (see below) may be linked under the driver and the driver provides the functions of a Signalling End Point (SEP) or Signalling Transfer Point (STP).7

Message Transfer Part (MTP) Level 3 (MTP3) Module

Figure 6.2. Message Transfer Part (MTP) Level 3 (MTP3) Module

The MTP driver supports all CCITT/ITU-T versions (Blue Book forward), ETSI and ANSI versions (1992 forward), including full transfer function. The MTP driver provides a specialized MTP interface to its users, in addition to an NPI Revision 2.0 connectionless interface. A TPI Revision 2.0 (connectionless) user interface support X/Open XNS 5.2 XTI library functions is also provided.

The MTP driver is a STREAMS driver that runs in the Linux kernel for maximum performance.

The Message Transfer Part (MTP) Level 3 (MTP3) module is responsible for providing MTP services to its users.

The Message Transfer Part (MTP) Level 2 (MTP2) module is responsible for providing MTP services to its users.

Message Transfer Part (MTP) Level 2 (MTP2) Module

Figure 6.3. Message Transfer Part (MTP) Level 2 (MTP2) Module

These are an existing OpenSS7 SS7 stack components; for documentation, see: mtp(4). Phase 1 activities for MTP3 and MTP2 include integration testing with the SG components.


7.1.6 MTP Level 2 User Adaptation Layer (M2UA) Driver

The M2UA driver provides the SG with the ability to act as both an M2UA SG (Signalling Gateway) and an M2UA AS (Application Server). In this project, the both the SG and AS functions are performed by the OpenSS7 Signalling Gateway Platform. M2UA is used primarily for redundancy between internal nodes of the SG. The M2UA driver accepts the transport of SL to SL-User interface from the SG to the AS.8 The M2UA driver links SCTP driver streams underneath it to provide the transport services for exporting the SL-User interface. The M2UA driver provides the same interface to its users as the OpenSS7 SL.

The M2UA driver is a STREAMS driver that runs in the Linux kernel for maximum performance.

This is an existing OpenSS7 SIGTRAN stack component: for documentation, see m2ua(4). Phase 1 activities for M2UA include integration testing with the SG components.


7.1.7 Signalling Link Multiplexing (SL-MUX) Driver

The SL-MUX is a Signalling Link Multiplexing (SL-MUX) driver for the OpenSS7 stack. It provides a convenient mechanism for the management of signalling links of a wide variety of types. The SL-MUX driver links signalling links conforming to the SL to SL-User interface and provides a global naming and Physical Point of Attachment scheme for all signalling links. V401P-SS7 signalling links, channel driver signalling links, M2PA signalling links and M2UA accessible signalling links can all be linked beneath the SL-MUX driver.

The SL-MUX driver is a STREAMS multiplexing driver that runs in the kernel for maximum performance.

This is an existing OpenSS7 SS7 stack component: for documentation, see sl-mux(4). Phase 1 activities for the SL-MUX include integration testing with the SG components.


7.1.8 MTP Level 2 Peer-to-Peer User Adaptation Layer (M2PA) Module

The M2PA module provides the SG with the ability to utilize SCTP-based high-speed signalling links. In this project, M2PA signalling links are used primiarily for backup C-Links between SG nodes acting as Signalling Transfer Points (STPs). The M2PA module pushes over an SCTP driver transport Stream to form a complete Signalling Link (SL). The M2PA module provides the same interface to its users as the OpenSS7 Signalling Link (SL).

The M2PA module is a STREAMS module that runs in the Linux kernel for maximum performance.

This is an existing OpenSS7 SIGTRAN stack component: for documentation, see m2pa(4). Phase 1 activities for M2PA include integration testing with the SG components.


7.1.9 Signalling Link (SL) Module

The signalling link module performs HDLC and SS7 Message Transfer Part Level 2 (Link) functions on a raw communications channel, such as that provided by the X400P-SS7 driver and the V401P-SS7 card. This module converts between the channel media stream (raw octet stream) and an SS7 signalling link signalling Stream. These Streams comprise SS7 signalling links and are linked under the SL-MUX or MTP driver.

The SL module supports CCITT/ITU-T versions (Blue Book forward), ETSI and ANSI versions (1992 forward), including Q.703 and Q.703 Annex B (HSL) operation. TTC JQ.703 (1994) is also supported. The SL module provides a specialized SL interface to its users, in addition to an NCR Comten CDI Revision 2.0 Style 2 connectionless interface.

The SL module is a STREAMS module that runs in the Linux kernel for maximum performance.

The Signalling Link (SL) module is responsible for providing SL services to its users.

Signalling Link (SL) Module

Figure 6.4. Signalling Link (SL) Module

This is an existing OpenSS7 SS7 stack component; for documentation, see: sl(4). Phase 1 activities for MTP2 include integration testing with the SG components.


7.1.10 Signalling Data Terminal (SDT) Module

The signalling data terminal module performs HDLC and lower level SS7 Message Transfer Part Level 2 (Link) functions including DAEDR, DAEDT, AERM, SUERM or EIM and SU Compression/Repetition on a raw communications channel or span, such as that provided by OpenSS7 Channel Drivers. This module converts between the raw channel media stream (raw octet stream) and an SS7 signalling data terminal Stream. These Streams comprise SS7 signalling data terminals and are pushed beneath the SL module.

The SDT module supports CCITT/ITU-T version (Blue Book forward), ETSI and ANSI versions (1992 forward), including Q.703 and Q.703 Annex B (HSL) operation. TTC JQ.703 (1994) is also supported. The SDT module provides a specialized SDT interface to it users, in addition to an NCR Comtem CDI Revision 2.0 Style 2 connectionless interface.

The Signalling Data Terminal (SDT) module is responsible for providing SDT services to its users.

Signalling Data Terminal (SDT) Module

Figure 6.5. Signalling Data Terminal (SDT) Module

This is an existing OpenSS7 SS7 stack component; for documentation see: sdt(4). Phase 1 activities for SDT include integration testing with the SG components.


7.1.11 Signalling Data Link (SDL) Module

The signalling data link module performs conversion between OpenSS7 channel drivers and the Signalling Data Link interface used by other SS7 modules and drivers. This module converts between the Channel primitives and the Signalling Data Link primitives. Streams with this module pushed comprise SS7 signalling data links and are pushed beneath the SDT module.

The SDL module supports CCITT/ITU-T version (Blue Book forward), ETSI and ASNI version (1992 forward), including Q.703 and Q.703 Annex B (HSL) operation. TTC JQ.703 (1994) is also supported. The SDL module provides a specialized SDL interface to its users, in addition to an NCR Comten CDI Revision 2.0 Style 2 connectionless interface.

The Signalling Data Link (SDL) module is responsible for providing SDL services to its users.

Signalling Data Link (SDL) Module

Figure 6.5b. Signalling Data Link (SDL) Module

This is an existing OpenSS7 SS7 stack component; for documentation see: sdl(4). Phase 1 activities for SDL include integration testing with the SG components.


7.1.12 Multiplex/Channel (MX/CH) Driver

The Multiplex/Channel (MX/CH) Driver performs soft-switching of multiplex Streams as well as channel access to channels within multiplex Streams. This driver links multiplex interfaces beneath it and presents both multiplex and channel interfaces to its users. For this project, the MX/CH driver is used to link V401P-MX Streams beneath the driver and provide channel access to DS0 or full DS1 channels within the multiplex for use by SS7 signalling links. Multiplex streams present an MX interface to its users. Channel streams present a CH interface to its users. The CH interfaces are converted to SDL Streams using the SDL module and then have SDT and SL modules pushed to form a complete Signalling Link stream.

The MX/CH drivers supports T1, E1 and J1 operation, as well as T3 and E2 operation. The driver provides a specialized MX and CH interface to its users.

This is an existing OpenSS7 channel stack component; for documentation see mx(4) and ch(4).

The Multiplex/Channel (MX/CH) driver is responsible for providing CH services to its users.


7.1.13 V401P-MX (X400-MX) Driver


7.1.14 Stream Control Transmission Protocol (SCTP) Driver

OpenSS7 has two implementations (STREAMS and Linux Sockets) that provide support for this new transport protocol and that provide transport for SIGTRAN and other protocols. The STREAMS SCTP implementation provides an NPI Revision 2.0 and TPI Revision 2.0 interface to its users. Alos supported is an X/Open XNS 5.2 XTI Library and ITOS (ISO over SCTP). The Linux Native SCTP implementation provides a Sockets interface.

This is an existing OpenSS7 SIGTRAN stack component; for documentation, see: sctp(4). Phase 1 activities for SCTP include integration testing with the SG components.


8 Software Architecture

This chapter details the software configuration of the OpenSS7 solutions. OpenSS7 stack software is based on the STREAMS facility running on the Linux Operating System. This provides for use of the Linux Operating System while maintaining portability and consistency with major UNIX operating systems that provide an SVR 4.2 ES/MP STREAMS facility.


8.1 Linux Operating System

The OpenSS7 STREAMS releases and stacks currently support the 2.4, 2.6 and 3.x Linux Kernel. A Linux kernel version greater than or equal to 2.4.18 is recommended for 2.4 kernels. The Linux 2.5 series kernels are not supported. A Linux kernel version greater than or equal to 2.6.9 is recommended for 2.6 kernels. Any kernel beginning with 3.0 in the 3.x kernel series is acceptable. Linux 2.4, 2.6 and 3.x kernels released by popular distributions are supported. These include kernel.org releases, RedHat (7.2, 9, EL3, AS/EL4, EL5, EL6), WhiteBox (EL3, EL4), Fedora Core (FC1-FC15), Debian (Woody-Wheezy), Ubuntu (6.10-11.04), SuSE (8.2-12.4 OSS, 9.0-12.1 SLES), CentOS(4, 5 and 6), Lineox (4 and 5), Scientific (5 and 6), PUIAS (5 and 6), Oracle (5 and 6). Currently our preferred distribution is CentOS 5 with all updates applied.

Although OpenSS7 STREAMS SS7 and SIGTRAN stacks are tested primarily on ix86 hardware, the stacks compile and install on PPC (MPC 8260, Freescale 440), HPPA, and other processor architectures supported by the Linux 2.4, 2.6 and 3.x kernels.

For the current project, RedHat AS/EL5 or CentOS 5 is recommended.


8.2 STREAMS Facility

OpenSS7 STREAMS SS7 and SIGTRAN stacks utilize a SVR 4.2 ES/MP STREAMS facility.


8.3 OpenSS7 SS7 and SIGTRAN Stacks

The OpenSS7 SS7 and SIGTRAN stacks are implemented using the STREAMS facility. Protocol moduels within the stack are implemented as STREAMS modules, device drivers, multiplexing drivers and pseudo-device drivers. The STREAMS facility has the ability to stack modules and multiplexing drivers above read or pseudo-device drivers using the STREAMS I_PUSH(7) an I_LINK(7) facilities. Since STREAMS modules and drivers run within the context of the Operating System Kernel using message-based scheduling, greatly increased performance is experienced over equivalent user-space applications. STREAMS modules and drivers communicate by passing priority. In addition, STREAMS provides memory management, timer, locking, syncrhonization, flow control and other facilities commonly used by protocol modules.

SS7 to ISO/OSI Mapping

Figure 7.1. SS7 to ISO/OSI Mapping

Each OpenSS7 protocol module provides standardized X/Open ISO/OSI interfaces as well as more SS7 specialized interfaces. Many of the OpenSS7 protocol modules provide TPI Revision 2.0 interfaces with support fot he OpenSS7 XTI/TLI Library.

STREAMS SS7/SIGTRAN Stack Architecture

Figure 7.2. STREAMS SS7/SIGTRAN Stack Architecture

Figure 7.2 illustrates the organization of STREAMS modules, multiplexing drivers, pseudo-device drivers and real device drivers in the OpenSS7 SS7 stack. At each interface, the equivalent SIGTRAN User Adaptation Layer (UA) can be used. So, for example, between MTP Level 3 and its Users, the M3UA protocol can be employed. Each UA provides the same lower layer interface and upper layer interface. So, M3UA provides an MTP/MTP-User interface at its lower layer interface as well as at it supper layer interface.


9 Hardware Architecture

Figure 8.1 illustrates the hardware configuration for the OpenSS7 Signalling Gateway Platform.

Platform Architecture

Figure 8.1. Platform Architecture

The configuration show in Figure 8.1 shows:

  • Two compute nodes attached in a fully redundant configuration.
  • Each compute node has 3 x V401P-SS7 cards proding quad DSX-1 connectivity per card, for a total of 12 DSX-1’s per compute node.
  • Each compute node is attached via cross-connect over 12 DSX-1’s (each) to a DACS which has drop-down capability on each pair of DSX-1’s consisting of one DSX-1 from each compute node.
  • On the IP network side, each compute node supports 2 GigE NIC ports.
  • Each NIC port on each compute node is attached to a GigE rail or swtich which subsequently attacheds to two Routers, one for Network A and one for Network B.
  • The configuration shown supports up to 288 low-speed (56 or 64 kbps) signalling links or up to 12 high-speed (1.544 Mpbs) signalling links.
  • Compute nodes communicate with each other over the IP network, either via local switch or remote router, using M2UA. This SIGTRAN protocol permits the compute node to logically share their V401P-SS7 hardware interfaces.
  • Compute nodes communicate with the associated STP pair via TDM links as well as using the M2PA protocol. The M2PA SIGTRAN protocol provides an IP-based high-speed SS7 link and is used to augment TDM links to implement C-Links on the platform.
  • Compont nodes act as SGP within the SG and provide MTP Level 3 and above connectivity to remote application servers using the M3UA SIGTRAN protocol. The M3UA SIGTRAN protocol exports the MTP to MTP-User interface and effectivley transports the interface to the application server from the signalling gateway.

10 Management Architecture


11 Logistics

11.1 Hardware

11.1.1 Sizing Considerations

11.2 Software

11.3 Consulting


11.4 Schedule

11.4.1 Gate 0 — Concept

11.4.2 Gate 1 — High-Level Design

11.4.3 Gate 2 — Detailed Design

11.4.4 Gate 3 — Development and Implementation

11.4.5 Gate 4 — System Test

11.4.6 Gate 5 — Acceptance Testing

11.4.7 Gate 6 — Support Complete

11.5 Cost


Appendix A Optional Application Support


Appendix B Optional Network Support


Appendix C Optional System Support


Appendix D Optional Platform Support


Appendix E Optional Protocol Support


Appendix F Optional Software Support


Appendix G Optional Hardware Support


Appendix H Optional Management Support


Appendix I Programmatic Interfaces


Appendix J Platform Sizing


Licenses

All code presented in this manual is licensed under the GNU Affero General Public License. The text of this manual is licensed under the GNU Free Documentation License, with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Please note, however, that it is just plain wrong to modify statements of, or attribute statements to, the Author or OpenSS7 Corporation.


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    Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU Affero General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU Affero General Public License, you may choose any version ever published by the Free Software Foundation.

    If the Program specifies that a proxy can decide which future versions of the GNU Affero General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program.

    Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.

  16. Disclaimer of Warranty.

    THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

  17. Limitation of Liability.

    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

  18. Interpretation of Sections 15 and 16.

    If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.

END OF TERMS AND CONDITIONS

How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

one line to give the program's name and a brief idea of what it does.
Copyright (C) year name of author

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see http://www.gnu.org/licenses/.

Also add information on how to contact you by electronic and paper mail.

If your software can interact with users remotely through a network, you should also make sure that it provides a way for users to get its source. For example, if your program is a web application, its interface could display a “Source” link that leads users to an archive of the code. There are many ways you could offer source, and different solutions will be better for different programs; see section 13 for the specific requirements.

You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU AGPL, see http://www.gnu.org/licenses/.


GNU Free Documentation License



GNU FREE DOCUMENTATION LICENSE
Version 1.3, 3 November 2008
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
http://fsf.org/

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
  1. PREAMBLE

    The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

    This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

    We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

  2. APPLICABILITY AND DEFINITIONS

    This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

    A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

    A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

    The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

    The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

    A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.

    Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

    The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

    The “publisher” means any person or entity that distributes copies of the Document to the public.

    A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.

    The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

  3. VERBATIM COPYING

    You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

    You may also lend copies, under the same conditions stated above, and you may publicly display copies.

  4. COPYING IN QUANTITY

    If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

    If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

    If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

    It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

  5. MODIFICATIONS

    You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

    1. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
    2. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
    3. State on the Title page the name of the publisher of the Modified Version, as the publisher.
    4. Preserve all the copyright notices of the Document.
    5. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
    6. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
    7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
    8. Include an unaltered copy of this License.
    9. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
    10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
    11. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
    12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
    13. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
    14. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
    15. Preserve any Warranty Disclaimers.

    If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

    You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

    You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

    The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

  6. COMBINING DOCUMENTS

    You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

    The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

    In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”

  7. COLLECTIONS OF DOCUMENTS

    You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

    You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

  8. AGGREGATION WITH INDEPENDENT WORKS

    A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

    If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

  9. TRANSLATION

    Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

    If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

  10. TERMINATION

    You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.

    However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

    Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

    Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.

  11. FUTURE REVISIONS OF THIS LICENSE

    The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

    Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document.

  12. RELICENSING

    “Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site.

    “CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versio