Intraplex® NetXpress™ - Simulcast Solutions · 2.10.1 RBS ... 2.12 Configuration Files Backup and Restoration ... 3.3 Wiring & External Connections

Intraplex NetXpress Audio IP Multiplexer & CM-30 IP Interface Module NetXpress LX Multiplexer CM-30 Common Module MA-230 Module Adapter

Version 1.01 For NetXpress LX Version 1.03

Installation and Operation Manual

Publication Information

2014 GatesAir, Inc. . Proprietary and Confidential.

GatesAir considers this document and its contents to be proprietary and confidential. Except for making a reasonable number of copies for your own internal use, you may not reproduce this publication, or any part thereof, in any form, by any method, for any purpose, or in any language other than English without the written consent of GatesAir. All others uses are illegal.

This publication is designed to assist in the use of the product as it exists on the date of publication of this manual, and may not reflect the product at the current time or an unknown time in the future. This publication does not in any way warrant description accuracy or guarantee the use for the product to which it refers.

GatesAir reserves the right, without notice to make such changes in equipment, design, specifications, components, or documentation as progress may warrant to improve the performance of the product.

GatesAir reserves the right, without notice to make such changes in equipment, design, specifications, components, or documentation as progress may warrant to improve the performance of the product.

Trademarks

AudioLink PLUS, HD Link, IntraGuide, Intraplex

, NetXpress, NetXpress LX, STL PLUS

, SynchroCast

, and

SynchroCast3 are trademarks of GatesAir Corporation. Other trademarks are the property of their respective owners.

Customer Service Contact Information

www.gatesair.com

GatesAir

3200 Wismann Lane

Quincy, Il 62305 USA

For Technical Support including Service, Training, Repair and Service Parts:

www.gatesair.com/services/technical-support.aspx

Americas:

24/7 Technical Support +1 217 222 8200

Email [email protected]

Europe, Middle East and Africa:



Asia:



Version Date Revision History Editor

1.01* 6/21/12 Corrected AC power wattage in Power section.

Corrected default IP address on Table 3-2.

Updated section to reflect default system mode setting change from E1 to T1. Added guidelines for determining system mode needed.

Added port numbers for specific network protocols.

LD

1 9/20/10 Developed manual. LD

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GatesAir, Inc. i Intraplex Products

Table of Contents

Section 1 Introduction ................................................................ 1-1

1.1 Key Features .................................................................................... 1-1

1.2 Manual Use ...................................................................................... 1-1

1.3 Manual Scope ................................................................................... 1-2

1.4 Components ..................................................................................... 1-2 1.4.1 Main Equipment Shelf ............................................................................1-2

1.4.2 CM-30 IP Interface Module ......................................................................1-2

1.4.3 MA-230 Module Adapter .........................................................................1-4

1.4.4 Other Modules and Module Adapters ........................................................1-4

1.4.5 Indicator Lights .....................................................................................1-4

1.5 Web Browser User Interface .............................................................. 1-4

Section 2 Functional Design ........................................................ 2-1

2.1 Network Concepts and Considerations ................................................. 2-1 2.1.1 MTU throughout the Network ...................................................................2-1

2.1.2 DHCP Use .............................................................................................2-1

2.1.3 Routing Table Construction .....................................................................2-1

2.1.4 WAN Port Auto-negotiation ......................................................................2-2

2.1.5 ICMP Support ........................................................................................2-2

2.1.6 IGMP Multicast ......................................................................................2-2

2.2 Streams ........................................................................................... 2-3 2.2.1 Stream Types ........................................................................................2-3

2.2.2 Stream Addressing .................................................................................2-4

2.2.3 Multicast Group Addressing .....................................................................2-4

2.2.4 Telephony .............................................................................................2-5

2.2.5 Echo Cancellation ...................................................................................2-5

2.2.6 Packetization and Overhead ....................................................................2-6

2.2.7 Packet Jitter Compensation .....................................................................2-6

2.2.8 Packet/Stream Information Calculation .....................................................2-6

2.2.9 Stream Statistics ...................................................................................2-7

2.3 System Security ............................................................................... 2-7 2.3.1 NetXpress LX Login ................................................................................2-8

2.3.2 Management Protocols on an Interface .....................................................2-8

2.3.3 IP Access List Use ..................................................................................2-8

2.3.4 SNMP Communities ................................................................................2-8

2.4 NetXpress LX QoS ............................................................................ 2-9 2.4.1 COS Levels for Stream Data ....................................................................2-9

2.4.2 TOS Byte Marking for Outbound Stream Packets .......................................2-9

2.4.3 User-Defined TOS Byte Setting for Outbound SNMP and HTTP Packets .........2-9

2.5 NetXpress LX Internal TDM Busses ..................................................... 2-9 2.5.1 Compatibility with Intraplex TDM Channel Modules ....................................2-9

2.5.2 TDM Channel Loopbacks ....................................................................... 2-11

2.5.3 TDM Bus Mapping ................................................................................ 2-11

2.6 System Time-of-Day ....................................................................... 2-12

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2.7 System Timing ............................................................................... 2-12 2.7.1 Types of System Timing ....................................................................... 2-12

2.7.2 NetXpress LX Timing Scenarios ............................................................. 2-13

2.8 NetXpress LX System and FEC ......................................................... 2-17

2.9 Power ........................................................................................... 2-18

2.10 Voice Signaling .............................................................................. 2-18 2.10.1 RBS ................................................................................................... 2-19

2.10.2 CAS ................................................................................................... 2-19

2.11 Software Download ........................................................................ 2-19

2.12 Configuration Files Backup and Restoration ....................................... 2-19

2.13 Fault Detection and Reporting .......................................................... 2-20 2.13.1 Alarm Hierarchy .................................................................................. 2-20

2.13.2 Alarm History ...................................................................................... 2-20

2.13.3 SNMP Traps Use for Fault Reporting ....................................................... 2-20

Section 3 Installation & Wiring ................................................... 3-1

3.1 Installation Preparation...................................................................... 3-1 3.1.1 Tools & Cables Required .........................................................................3-1

3.1.2 Equipment Unpacking & Inspection ..........................................................3-1

3.2 Installation ....................................................................................... 3-2 3.2.1 Shelf Installation ...................................................................................3-2

3.2.2 CM-30 Module Kit Installation ..................................................................3-2

3.2.3 Channel Module Installation ....................................................................3-8

3.2.4 Power Supply Installation .......................................................................3-9

3.3 Wiring & External Connections ............................................................ 3-9

3.4 Power Application ........................................................................... 3-15

Section 4 Configuration & Operation .......................................... 4-1

4.1 Download Current Software................................................................ 4-1

4.2 Configuration Process ........................................................................ 4-1 4.2.1 Connect and Log On to Access NetXpress LX Home Page ............................4-1

4.2.2 View System Mode .................................................................................4-2

4.2.3 Perform General Setup ...........................................................................4-2

4.3 NetXpress LX Pages ......................................................................... 4-13 4.3.1 Start at the NetXpress LX Home Page ..................................................... 4-13

4.3.2 Define & Review Fault Information ......................................................... 4-15

4.3.3 Configure the System ........................................................................... 4-20

4.3.4 Configure the Network ......................................................................... 4-34

4.3.5 Configure Streams ............................................................................... 4-46

4.3.6 Check Multiplexer Performance .............................................................. 4-56

4.3.7 Set Up Security ................................................................................... 4-68

4.3.8 Send Echo Requests ............................................................................. 4-72

4.3.9 Configure CM-30 Module ...................................................................... 4-72

4.3.10 Configure Individual Modules (TDM Modules) .......................................... 4-75

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Section 5 Testing & Troubleshooting ......................................... 5-1

5.1 Testing ........................................................................................... 5-1 5.1.1 General Status Test ...............................................................................5-1

5.1.2 CM-30 Alarm Test ..................................................................................5-2

5.1.3 Ping Test ..............................................................................................5-4

5.1.4 Streams Test ........................................................................................5-4

5.2 Troubleshooting ................................................................................ 5-6 5.2.1 Channel Module Addition ........................................................................5-6

5.2.2 Web Browser Interface ...........................................................................5-6

Section 6 Specifications .............................................................. 6-1

6.1 Detailed Specifications ...................................................................... 6-1 6.1.1 NetXpress LX IP Multiplexer ....................................................................6-1

6.1.2 CM-30 IP Interface Module ......................................................................6-3

6.2 Notice of FCC Compliance .................................................................. 6-5

Appendix A T1/E1-to-NetXpress LX Multiplexer Conversion ....... A-1

A.1 Installation Preparation ..................................................................... A-1 A.1.1 Equipment Unpacking & Inspection ......................................................... A-1

A.1.2 Card Slot Selection ............................................................................... A-1

A.2 IP Multiplexer Conversion .................................................................. A-2 A.2.1 CM-30 & MA-230 Installation into the First Multiplexer .............................. A-2

A.2.2 First CM-30 IP Interface Module Configuration .......................................... A-4

A.2.3 CM-30 & MA-230 Installation into the Second Multiplexer .......................... A-4

A.2.4 Second CM-30 IP Interface Module Configuration ...................................... A-4

A.2.5 Configuration of Both CM-30 Modules to Work Together ............................ A-4

A.2.6 Removal of the Original Common Modules ............................................... A-6


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iv GatesAir, Inc. Intraplex Products

Figures

Figure 1-1. NetXpress LX-300 Front Panel with Cover .................................................1-2

Figure 1-2. NetXpress LX-100 Front Panel with Cover .................................................1-2

Figure 1-3. CM-30 IP Interface Module ......................................................................1-3

Figure 2-1. Carrier Multicast Backbone Example .........................................................2-5

Figure 2-2. NetXpress LX Web Interface Login ...........................................................2-8

Figure 2-3. TDM Loopback Scenarios ...................................................................... 2-11

Figure 2-4. Timing Synchronization ........................................................................ 2-14

Figure 2-5. Point-to-Point Timing Synchronization .................................................... 2-14

Figure 2-6. Stream Timing Synchronization ............................................................. 2-15

Figure 2-7. Streams with Different Synchronization Sources ...................................... 2-15

Figure 2-8. Timing Synchronization with GPS ........................................................... 2-16

Figure 2-9. Timing with Off-Air Monitor Streams ...................................................... 2-17

Figure 3-1. NetXpress LX 1RU and 3RU Multiplexers ...................................................3-2

Figure 3-2. CM-30 Module and Indicator Lights ..........................................................3-3

Figure 3-3. Contact Input Circuitry ...........................................................................3-5

Figure 3-4. MA-230 Module Adapter Top and Faceplate Views ......................................3-6

Figure 3-5. MA-230 Connectors with Indicator Lights ..................................................3-7

Figure 3-6. CM-30 Module and MA-230 Midplane Insertion ..........................................3-8

Figure 3-7. 3RU NetXpress LX Rear Panel Connectors with MA-230 Module Adapter...... 3-10

Figure 3-8. 1RU NetXpress LX Rear Panel Connectors with MA-230 Module Adapter...... 3-10

Figure 3-9. Connection for DC Operation of 3RU Systems .......................................... 3-12

Figure 3-10. Connection for DC Operation of 3RU Systems with Two Power Sources ....... 3-12

Figure 3-11. Connection for AC Operation of 3RU System with External Signal Battery ... 3-13

Figure 3-12. Connection for AC Operation of 1RU System with External Signal Battery ... 3-13

Figure 3-13. 3RU Multiplexer Rear Panel with ACS-OPT1 Dual AC Power Feed Option ..... 3-14

Figure 4-1. Intraplex NetXpress LX Home Page ..........................................................4-2

Figure 4-2. Networking | Forwarding Table ................................................................4-3

Figure 4-3. Forwarding Table | Create a New Route Dialog Box ....................................4-4

Figure 4-4. Security | IP Access List .........................................................................4-4

Figure 4-5. IP Access List | Create IP Access List Entry Dialog Box ...............................4-5

Figure 4-6. System Cfg | TDM Bus Information ..........................................................4-5

Figure 4-7. System Cfg | Software Images Configuration ............................................4-6

Figure 4-8. Streams ...............................................................................................4-7

Figure 4-9. Stream Creation Stage 1 .....................................................................4-7

Figure 4-10. Stream Creation Stage 2 .....................................................................4-8

Figure 4-11. Stream Creation Stage 3 for Multi-Unicast .............................................4-8

Figure 4-12. Stream Creation Stage 4 (TDM to IP) ....................................................4-9

Figure 4-13. Stream Creation Summary ................................................................... 4-10

Figure 4-14. System Cfg | System Timing ................................................................. 4-11

Figure 4-15. Networking | SNMP Configuration .......................................................... 4-12

Figure 4-16. System Cfg | Configuration Files Backup/Restore ..................................... 4-13

Figure 4-17. Intraplex NetXpress LX Home Page ........................................................ 4-14

Figure 4-18. Current Alarms Page ............................................................................ 4-16

Figure 4-19. Alarm Definitions Page ......................................................................... 4-17

Figure 4-20. Specific Alarm Definition Dialog Box ....................................................... 4-17

Figure 4-21. Alarm History Page .............................................................................. 4-18

Figure 4-22. System Logging Page ........................................................................... 4-19

Figure 4-23. General Setup Page ............................................................................. 4-21

Figure 4-24. Contacts Page ..................................................................................... 4-22

Figure 4-25. Configure Input Contact Dialog Box ....................................................... 4-23

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Figure 4-26. Configure Output Contact Dialog Box ..................................................... 4-24

Figure 4-27. TDM Bus Information Page ................................................................... 4-24

Figure 4-28. Changes to System Mode Dialog Box ..................................................... 4-25

Figure 4-29. TDM Bus Configuration Page ................................................................. 4-25

Figure 4-30. TDM Bus Map Configuration Page T1 Mode ........................................... 4-27

Figure 4-31. Edit TDM Bus Map Configuration Page .................................................... 4-28

Figure 4-32. System Timing Page ............................................................................ 4-29

Figure 4-33. Software Images Page ......................................................................... 4-31

Figure 4-34. Configuration Files Backup/Restore Page ................................................ 4-33

Figure 4-35. Ethernet Interfaces Page WAN and LAN Interfaces ................................ 4-35

Figure 4-36. Forwarding Table ................................................................................. 4-37

Figure 4-37. Add a Route Dialog Box ........................................................................ 4-38

Figure 4-38. DiffServ Marking for Forwarded Packets Page .......................................... 4-39

Figure 4-39. Add a DiffServ Marking Entry Dialog Box ................................................ 4-40

Figure 4-40. DiffServ TOS to Priority Mapping Page .................................................... 4-41

Figure 4-41. Map TOS Value to Priority Level Dialog Box ............................................. 4-41

Figure 4-42. TOS Byte Configurations Page ............................................................... 4-42

Figure 4-43. SNMP Configuration Page ..................................................................... 4-43

Figure 4-44. UDP Listeners Table ............................................................................. 4-44

Figure 4-45. TCP Connections Table ......................................................................... 4-45

Figure 4-46. ARP Table ........................................................................................... 4-46

Figure 4-47. Streams Table ..................................................................................... 4-47

Figure 4-48. Stream Creation Stage 1 Page Stream Type ...................................... 4-48

Figure 4-49. Stream Creation Stage 2 Page Stream Features ................................. 4-49

Figure 4-50. Stream Creation Stage 3 Page IP Parameters .................................... 4-50

Figure 4-51. Stream Creation Stage 3 Page IP Config for All Streams (Multi-Unicast) 4-51

Figure 4-52. Stream Creation Stage 4 Page TDM Bus Parameters ........................... 4-52

Figure 4-53. Stream Creation Summary Page ............................................................ 4-54

Figure 4-54. Stream Edit Pages ............................................................................... 4-55

Figure 4-55. Stream Statistics Page ......................................................................... 4-57

Figure 4-56. Performance History Page ..................................................................... 4-57

Figure 4-57. Voice Signaling Statistics Page .............................................................. 4-58

Figure 4-58. Ethernet Interface Statistics Page WAN and LAN ................................... 4-59

Figure 4-59. SNMP Performance Page ....................................................................... 4-60

Figure 4-60. TCP/UDP Performance Page .................................................................. 4-62

Figure 4-61. ICMP Performance Page........................................................................ 4-64

Figure 4-62. IGMP Performance Page ....................................................................... 4-66

Figure 4-63. IP Performance Page ............................................................................ 4-67

Figure 4-64. Web Interface User Accounts Page ......................................................... 4-69

Figure 4-65. Add User Account Dialog Box ................................................................ 4-70

Figure 4-66. Edit User Account Dialog Box ................................................................ 4-70

Figure 4-67. IP Access List Page .............................................................................. 4-71

Figure 4-68. Add an IP Address Dialog Box ............................................................... 4-71

Figure 4-69. Ping Utility Page .................................................................................. 4-72

Figure 4-70. CM-30 Common Module: General Page ................................................... 4-73

Figure 4-71. CM-30 Common Module: Revisions Page ................................................ 4-74

Figure 4-72. CM-30 Common Module: Program Boot ROM Page ................................... 4-75

Figure 4-73. DS-64NC Configuration Page ................................................................. 4-76

Figure 4-74. DS-64NC Status Page .......................................................................... 4-76

Figure 4-75. PT-353 Configuration Page.................................................................... 4-76

Figure 4-76. PT-353 Status Page ............................................................................. 4-78

Figure 4-77. VF-25E Configuration Page ................................................................... 4-80

Figure 4-78. VF-25E Status Page ............................................................................. 4-81


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vi GatesAir, Inc. Intraplex Products

Figure 4-79. DS-64NC Configuration Page ................................................................. 4-83

Figure 4-80. DS-64NC Status Page .......................................................................... 4-85

Figure 5-1. NetXpress LX 3RU Multiplexer Front View, Closed ...................................5-1

Figure 5-2. NetXpress LX Web Interface Home Page ...................................................5-2

Figure 5-3. Faults | Current Alarms Table ..................................................................5-3

Figure 5-4. Faults | Alarm History Log ......................................................................5-3

Figure 5-5. Ping Utility ............................................................................................5-4

Figure 5-6. Performance | Streams Statistics Table ....................................................5-5

Figure A-1. CM-30 Module and MA-230 Midplane Insertion ......................................... A-2

Tables

Table 2-1. NetXpress LX Stream User and Computed Parameters ..................................2-7

Table 2-2. NetXpress LX-supported TDM Channel Modules .......................................... 2-10

Table 2-3. NetXpress LX FEC Performance Data......................................................... 2-18

Table 3-1. CM-30 Indicator Light Descriptions .............................................................3-4

Table 3-2. CM-30 Switch Settings ..............................................................................3-4

Table 3-3. MA-230 Module Adapter SW1 Switches and Functions ...................................3-6

Table 3-4. MA-230 In/Out and Contact Port Pin Assignments ........................................3-7

Table 3-5. Power and Alarm Connectors ................................................................... 3-11

Table 4-1. TDM Bus Map Profiles ............................................................................. 4-26

Table 4-2. States Associated with Streams ............................................................... 4-48

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GatesAir, Inc. 1-1 Intraplex Products

Section 1 Introduction This manual covers both the NetXpress LX IP multiplexer and the CM-30 IP interface module. The NetXpress LX multiplexer provides convenient provisioning and management tools to enhance operational efficiency. This IP platform supports both unicast and multicast and is compatible with the Intraplex NetXpress multiplexer.

The NetXpress LX multiplexer combines the technology of the original NetXpress multiplexer in a module configuration compatible with Intraplex T1 or E1 systems. The NetXpress LX multiplexer is available in either a 3RU frame with capacity for up to 17 application modules or a 1RU frame that can hold five application modules. This multiplexer can work in a simple point-to-point and point-to-multipoint designs and also as an edge device with the NetXpress multiplexer in large, multisite networks.

While the CM-30 IP interface module operates as the command module in a NetXpress LX multiplexer, this module can also replace the network interface module in an existing T1 or E1 system, converting

it to IP while utilizing the existing chassis with all its audio, voice, and data modules. With the CM-30 module, you can easily transition an existing Intraplex T1 or E1 system to cost-effective IP transmission.

1.1 Key Features

The NetXpress LX systems features include

CM-30 IP interface module, which can convert existing T1 or E1 systems to IP

Compatibility with Intraplex NetXpress systems

Wide variety of audio, voice, and data interface modules

Optional echo cancellation for 2-wire voice circuits

Transport of two contact closures in each direction

Adjustable packet size

Programmable jitter buffer depth

Advanced Intraplex forward error correction

Quality of Service (QoS) priority tagging

Unidirectional or bidirectional unicast streaming

Unidirectional multicast streaming

Web browser user interface

SNMP control

Current and previous software revision storage

Network statistics monitoring

Event logging

1.2 Manual Use

Use this manual as the primary reference document for installing, configuring, operating, and troubleshooting the NetXpress LX multiplexer and the CM-30 IP interface module. If you have additional questions pertaining to the operation of your Intraplex system, you can contact GatesAir

Customer Service:

U.S., Canada, and Latin America: +1-217-222-8200 or [email protected]

Europe, Middle East, and Africa: +44-118-964-8100 or [email protected]

Asia and Pacific Rim: +852-2776-0628 or [email protected]

mailto:[email protected]:[email protected]:[email protected]

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1.3 Manual Scope

The Table of Contents helps you locate specific topics. These guidelines give general information on manual sections.

Readers unfamiliar with the NetXpress LX system and/or the CM-30 IP interface module Use this manual as a tutorial. Read or skim all sections in order.

Installers If you are already familiar with the NetXpress LX system and/or the CM-30 IP interface module, finish reading this section and go directly to Section 3 Installation & Wiring

for step-by-step installation instructions.

Transmission and Planning Engineers The NetXpress LX and CM-30 operation and configuration overview is in Section 2 Functional Design, and specific instructions are in Section 4 Configuration & Operation. You can find output, power, and other specification information in Section 6 Specifications.

Maintenance Technicians Section 5 Testing & Troubleshooting discusses system tests and troubleshooting solutions. Individual channel module setup and test procedures can be found in

the manuals for the modules shipped with your system.

1.4 Components

1.4.1 Main Equipment Shelf

The NetXpress LX chassis has two rack-mount equipment sizes:

NetXpress LX-300 19-inch wide, 5 -inch high 3RU (Figure 1-1)

NetXpress LX-100 19-inch wide, 1 -inch high 1RU (Figure 1-2)

Figure 1-1. NetXpress LX-300 Front Panel with Cover

Figure 1-2. NetXpress LX-100 Front Panel with Cover

Each shelf is equipped with a CM-30 module, a MA-230 module adapter, and slots for plug-in channel modules and module adapters.

The NetXpress LX-100 multiplexer has a single built-in AC power supply. The LX-300 multiplexer has a

single plug -in AC or DC power supply and optional secondary plug-in AC or DC supplies.

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1.4.2 CM-30 IP Interface Module

The CM-30 module (Figure 1-3) is the command center for the NetXpress LX IP multiplexing system.

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Figure 1-3. CM-30 IP Interface Module

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This module acts as an IP network interface, a packet engine, and a system manager. When coupled

with the MA-230 module adapter (Section 1.4.3), the CM-30 module provides shelf management control, WAN and LAN traffic control through 10/100Base-T ports, and timing control for external stream traffic and system synchronization.

You can use a CM-30 module in place of, but not at the same time as, a T1 or E1 common module (CM-3, CM-5, CM-5RB, CM-6, CM-7, or CM-7RB) in an existing Intraplex T1 or E1 multiplexer. You can then revert back to T1 or E1 at a later date by simply removing the CM-30 module and reinserting the original common module.

1.4.3 MA-230 Module Adapter

The MA-230 module adapter provides connectivity for the CM-30 module. The MA-230 module adapter connects to the CM-30 module in the rear of the shelf and features these communication ports:

Two 10/100Base-T ports (WAN and LAN)

Timing in/out for external stream and system synchronization

Contact I/O for external control

1.4.4 Other Modules and Module Adapters

The NetXpress LX system offers five channel card slots (1RU shelf) or 17 channel card slots (3RU shelf) for Intraplex audio, voice, and data modules.

Intraplex module adapters are installed in the rear of the shelf and work in conjunction with the channel access cards installed in the front.

1.4.5 Indicator Lights

Four system status indicator lights located on the NetXpress LX power supply are visible when the front shelf cover is on (Figures 1-1 and 1-2).

POWER This green light is on when the multiplexer is powered.

NORMAL This green light is on when no major nor minor alarm is present.

ALERT This yellow light is on when a minor alarm condition exists.

ALARM This red light is on when a major alarm condition exists.

Section 5 defines major and minor alarm conditions.

The CM-30 module has indicator lights as well, which are visible when the front shelf cover is off. Section 3.2.2 gives more information about CM-30 indicator lights.

1.5 Web Browser User Interface

You can control functionality of your NetXpress LX unit and access network statistics and system status through the NetXpress LX Home page. You can choose to run simultaneous software windows; each connected to a different NetXpress LX system in the network. The Web browser interface, in conjunction with an SNMP network manager, lets you control and monitor your system from one

operation center. You can access the Home page from the network management system to research a

particular problem or obtain a graphical view of system configuration or status. Section 4 Configuration & Operation gives more information on this interface software.

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Section 2 Functional Design This section describes the intent of IP multiplexing and day-to-day operations of the NetXpress LX system and the CM-30 IP interface module. The section also describes how to use the IP multiplexer and interface module to configure real-time payload transport of audio and data over existing IP networks.

Packet-based media transport with the NetXpress LX system or the CM-30 module provides these features:

Transport of audio, voice, data, and video

Flexibility when integrating to business applications, systems, and networks

Network monitoring

Error mitigation

Transition and migration from legacy systems with reuse of modules and components

2.1 Network Concepts and Considerations

When looking at the NetXpress LX system (or the CM-30 module) and packet-switched services as a

whole, consider these network-related concepts:

MTU throughout the network

DHCP use

Routing table construction

WAN port auto-negotiation

ICMP support

Redundant WAN link configuration

IGMP multicast

2.1.1 MTU throughout the Network

Prior to configuring a stream, you need to know end-to-end MTU (Maximum Transmission Unit) between stream endpoints, which you can measure using an external server or router and running the Path MTU tool. The stream payload must be smaller than the path MTU, otherwise fragmentation

occurs, the stream does not come up, and the NetXpress LX system does not support re-assembly.

2.1.2 DHCP Use

Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a DHCP server to automatically assign an IP address to an individual computers IP network interface. DHCP dynamically assigns a number from a defined range of numbers configured for a given network.

The NetXpress LX system supports dynamic address assignment for its LAN interface using DHCP. On the WAN interface, only static IP address assignment is supported. You can elect to enable the DHCP option for the management interface from the Networking Ethernet Interfaces Web page (Section

4.3.4 Configure the Network). If DHCP is enabled and the system fails to successfully retrieve an IP address, it defaults to the factory default address 192.168.1.1.

2.1.3 Routing Table Construction

The behavior of the NetXpress LX system within the customers network is that of an IP host. As such, the NetXpress LX routing table is used solely to route internally generated packets. For streams that are unicast, the determination of the next-hop gateway to reach the remote NetXpress LX shelf is done by examining the system routing table.

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Routes in the routing table fall into two basic categories: automatic routes and user-defined routes.

The NetXpress LX system adds automatic routes based on the interface IP addresses. These routes are called directly connected routes and are present to identify local subnets. If the destination for all NetXpress LX traffic (stream and management) is to a host on its local subnet, no user routes are

needed. In most cases, however, you need to add routes to remote networks or hosts so that the NetXpress LX system can successfully send traffic to it. In the simplest case, if there is only one gateway on its WAN subnet, a default route (such as 0.0.0.0/0.0.0.0 next-hop gatewayIP) pointing to that gateway should be added. You can manage the NetXpress LX routing table from the NetXpress LX Home page (Section 4.3.4.2 Forwarding Table) or via direct SNMP access of the proprietary route management MIB (Management Information Base).

2.1.4 WAN Port Auto-negotiation

The auto-negotiation mechanism accommodates multi-speed Ethernet network devices. Auto-negotiation occurs when a physical connection is made between a NetXpress LX Ethernet port and an Ethernet port on a network switch or router. During this process, the two Ethernet devices use a

protocol to determine at what speed (10 Mbps or 100 Mbps) they communicate and whether the

exchange of data occurs in a half-duplex (only one end transmits at a time) or full-duplex manner.

With the NetXpress LX system, you can enable or disable auto-negotiation for the WAN ports because it is crucial that the link characteristics are set correctly to facilitate the transmission of stream data. Auto-negotiation should be enabled when the network port to which the NetXpress LX system is being connected is capable of negotiating to a mode of 100 Mbps or 10 Mbps and full-duplex operation. When auto-negotiation is disabled, each Ethernet port is set to operate at 100 Mbps speed in full-duplex mode, the optimum setting. If the anticipated stream data rate is low enough, the WAN port

can operate effectively at 10 Mbps. Operating the WAN port in half-duplex mode should be avoided. Both sides of the link need to be set for auto-negotiation. If not, the NetXpress LX system configures itself for 10 Mbps, half duplex, and streams experience dropped packets due to collision on the Ethernet link.

The LAN port is always set to auto-negotiate. The management port can satisfy its function even when operating at 10 Mbps in half-duplex mode.

Note: Do not operate auto-negotiation on only one side of the NetXpress LX link. To work properly,

both sides (NetXpress LX system and connecting device) must be enabled for auto-negotiation. The NetXpress LX system does not revert to 100 Mbps full-duplex if it is configured to auto-negotiate and the other device is manually configured for 100 Mbps full-

duplex.

2.1.5 ICMP Support

The ICMP (Internet Control Message Protocol) delivers error and control messages from hosts to message requestors. An ICMP test may determine whether a destination is reachable. The ICMP messages typically report errors in the processing of datagrams. Additionally, ICMP provides flow control and first-hop gateway redirection. On the NetXpress LX WAN port, there is an option to block ICMP error messages, but the ping messages are always allowed.

2.1.6 IGMP Multicast

The NetXpress LX system (or the CM-30 module in an original Intraplex system) interoperates with multicast routers using the Internet Group Management Protocol (IGMP). The IGMP Multicast mode involves transmission to specific hosts through IGMP routers. This scheme allows you to route specific packets onto specific segments, thereby segregating unwanted traffic from narrow segments.

The NetXpress LX system supports IGMP v2 messages. When a receive multicast stream is

configured, it sends out IGMP membership reports. Similarly, when the multicast streams are deleted, the NetXpress LX system sends out an IGMP Leave message and also responds to the membership

2 Functional Design NetXpress LX & CM-30 Installation & Operation Manual

Version 1.01


queries from the router. It supports the proprietary IGMP statistics MIB to account for all incoming and

outgoing messages.

2.2 Streams

Within the NetXpress LX multiplexer or an original Intraplex multiplexer, the CM-30 IP interface module uses packet streaming to transport audio signals.

2.2.1 Stream Types

2.2.1.1 Unidirectional versus Bidirectional

Packet streams can be unidirectional or bidirectional. In other words, streams can travel in one direction (transmitted or received) or two directions (transmitted and received). The CM-30 module supports both unidirectional and bidirectional packet streaming.

Most circuit types (such as voice and two-way data circuits) are bidirectional, or full-duplex. Full-

duplex circuits require identical full-duplex (transmit or receive) channel modules at both ends of the channel they occupy within a system. Other circuit types (such as program audio channels) are unidirectional (simplex). They always have a transmitter module at one end and a receiver module at the other. Most bidirectional (full-duplex) channel modules can also be set up to operate in a unidirectional (simplex) mode.

2.2.1.2 Unicast versus Multicast

Packet streams can also be classified as unicast or multicast. Unicast describes transmitting a piece of information (a packet stream in this case) from one point to another point. Unicast transfer mode is still the predominant form of transmission on LANs and within the Internet. Standard unicast applications include HTTP, SMTP, FTP, and Telnet.

Multicast describes communication where a piece of information is sent from one or more points to a

set of other points (a multicast group address). There may be one or more senders and the information is sent to a set of receivers (there may be no receiver or any number of receivers). With

multicasting, the same packet is delivered simultaneously to a group of clients. Multicast applications must use the UDP (User Datagram Protocol) transport protocol, since TCP (Transmission Control Protocol) only supports the unicast mode.

Most circuits provided by Intraplex multiplexer systems are unicast, including those provided with the NetXpress LX system. However, several types of channel modules can be configured for point-to-multipoint operation (multicast). For example, you can set up a single program audio transmitter

module and several program audio receiver modules in a point-to-multipoint or broadcast circuit configuration, allowing multiple locations to receive the same program audio signal.

If your network does not support multicasting, you can configure the NetXpress LX system to multi-unicast up to four destinations. The programming source must be in contiguous time slots on TDM Bus A. The receivers can be on the internal TDM bus. Section 4.3.3.4 TDM Bus Mapping Configuration gives additional multi-unicast information.

2.2.1.3 Voice Streams versus Data Streams

Streams which are intended to carry information for voice grade audio modules often require additional signaling information to support pulse dialing, off-hook condition call progress or ringing states. Special signaling support is required to transport this added information. Voice audio streams carrying telephone calls are also prone to audio echo back from the receiver. You can use echo canceling circuits to eliminate this problem. Streams used for transporting linear or compressed wideband audio modules or other forms of raw information present their data directly into each

channel and do not require signaling support.


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2.2.2 Stream Addressing

The stream addressing process involves designating a destination IP address for both unicast and

multicast IP streams (Section 4.3.5 Configure Streams). During the process of adding streams, individual streams are designated as either unicast or multicast in the Transmission Type field (Section 4.3.5.1 Stream Creation).

When you create a stream, a UDP port number must be specified for both the local and remote NetXpress LX devices. The RTP protocol conversation between the two devices takes place through the specified UDP ports.

The range for UDP port numbers must be greater than or equal to 50000 and a multiple of 5, ending

in either a 0 or a 5. For unicast and multicast receive streams, the combination of peers IP address and source and destination UDP ports must be unique. For multicast transmit streams, each stream must have unique ports.

Many networks use a device known as a firewall at the entry point to the network to provide security against hackers and other undesirable applications. Usually, network devices in the private network

behind the firewall can freely transmit out using any UDP port number. However, devices are blocked

from receiving packets using a UDP port number until a packet is transmitted out the firewall using the same UDP port. When setting up the network for a NetXpress LX installation, you may need to configure the firewall to allow communication on the UDP port numbers used for stream traffic before attempting to bring up a stream.

2.2.3 Multicast Group Addressing

The CM-30 IP interface module, within the NetXpress LX system or an original Intraplex system, supports multicast use for stream transmission and supports creating up to 32 transmit, receive, or a combination of transmit and receive streams. This system does not make any restrictions on the type of multicast address used for a stream destination. Therefore, you determine how you want the multicast address space to be administered. Figure 2-1 represents a scenario where multicast addresses are administratively scoped. However, some customers may also require GLOP assignment by the carrier WAN, using address ranges 233.x.x.x, and the NetXpress LX system can

accommodate that addressing scheme as well. Section 4.3.5.1 Stream Creation gives additional

information regarding multicast addresses.


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Figure 2-1. Carrier Multicast Backbone Example

2.2.4 Telephony

The CM-30 module and NetXpress LX system allow you to create streams whose endpoints are

Intraplex voice channel modules that support telephone signaling (for example, the VF-15E, VF-16AE, and VF-25 modules). The voice circuits generate signaling bits which the NetXpress LX system

transports out-of-band and reinserts onto the NetXpress LX internal TDM bus at the receive end. No more than 20 telephony streams are allowed in-service at one time.

Telephony streams can be easily identified in the stream table by the telephone icon after the stream name. The color of the icon, (red, yellow, or green) indicates the current status of the out-of-band signaling transfer. The NetXpress LX Performance menu provides statistics on signaling packet transmission, and these statistics are cleared when the other stream statistics are cleared.

The TDM bus in T1 systems inherently supports signaling. In E1 systems, the signaling bits are carried

on the internal TDM bus using Channel Associated Signaling (CAS). Telephony streams need to originate and terminate on busses where the CAS mode is enabled. You can select the specific TDM busses for the telephony streams on the TDM Bus Edit screen (System Config | TDM Bus | TDM Bus Edit). When the CAS mode is enabled, the NetXpress LX system uses Time slot 16 to carry the signaling bits for all the other channels on that bus; this time slot is not available to carry normal traffic.

2.2.5 Echo Cancellation

The NetXpress LX system can provide echo cancellation for voice circuits using up to 2 optional echo canceller cards that plug onto the CM-30 module. Each board can provide echo cancellation for up to 30 channels per echo canceller card on the TDM bus.

Echo cancellation can only be enabled for full-duplex streams with identical bus/channel configuration in the transmit (Tx) and receive (Rx) direction, and both endpoints of the stream need to have an

echo canceller card installed. Echo cancellers are needed in 2-wire modules (for example, the VF-15E


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or 16AE module) but not in 4-wire modules (for example, the VF-25E module). When using echo

cancellation, you should not configure streams to encapsulate more than 60 frames per packet.

2.2.6 Packetization and Overhead

Packetization is a process in which frames of data from the TDM bus are collected into IP packets for transmission through the IP network. A frame on a NetXpress LX TDM bus is divided into 32 partitions or time slots, each containing a byte of data. Because of the serial nature of the TDM bus, an entire TDM bus frame encompasses 125 s in time. The stream packetization interval defines the number of

TDM frames collected by the NetXpress LX system into a single packet for transmission. The higher

the packetization interval, the greater the accumulation delay introduced to the program because each frame must be accumulated before the packet can be created. Note that the total program delay is a combination of packetization delay and network delay.

Each packet in a NetXpress LX stream contains 44 bytes of non-program data (overhead) corresponding to the header information required for the IP, UDP, and RTP protocol layers. The ratio of non-program data to program data for a packet can be considered the overhead required to get the

packet through the network. The higher the overhead, the more the network bandwidth available to an application used to transmit non-program data. Program delay can be minimized by using a small packetization interval at the expense of an increase in overhead. Conversely, increasing the packetization interval decreases the overhead but increases the program delay (Table 2-1).

Another overhead determination factor is the number of time slots from each TDM frame that get placed in the packet. As this number increases, the stream overhead decreases because the ratio of overhead data to program data decreases. However, the number of time slots consumed from each

frame does not affect the program delay. Therefore, it is desirable to combine time slots from a TDM bus headed for the same destination into a single stream to reduce overhead and to make the best use of available network bandwidth.

2.2.7 Packet Jitter Compensation

In an IP network, the time required for a packet to travel through the network from sender to receiver

is not guaranteed to be maintained. As a result, the receiver can see the interval between the arrival

of packets vary throughout the reception of the packet stream. For a given packet, the difference between the packets delay and the average of the delay values for all packets in the stream is known as jitter. The jitter can be positive or negative depending on whether the packet delay is less than or greater than the average delay.

For many network services, packet jitter is not an issue, and no technique is needed to compensate. However, the continuous playout nature of audio and video require that there must be some means of

guaranteeing that the receiver always has the next packet of data when the previous packet is consumed. The receiver must also hold onto packets that arrive early so that they are available for playout at the proper time.

The NetXpress LX system compensates for stream packet jitter through the use of a jitter buffer. The system maintains a jitter buffer for each stream on the receive side. The buffer is sized so that the buffering delay is greater than the maximum packet delay expected through the network. In the

NetXpress LX system, you specify the jitter buffer size in number of packets ranging from 8 to 128 (Section 4.3.5.1 Stream Creation). The packetization interval of the stream controls the amount of

packet delay for which the jitter buffer can compensate. Increasing the number of TDM frames contained in a packet increases the size of the jitter buffer as measured in time.

2.2.8 Packet/Stream Information Calculation

Table 2-1 gives an example of user and computed parameters for a NetXpress LX stream. The user parameters represent user-defined stream parameters. The computed parameters are for packet information and network bandwidth based upon the user parameters. This table also gives formulas for how to derive computed parameters for a stream.


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Table 2-1. NetXpress LX Stream User and Computed Parameters

User Parameter Value Description

Number of TDM Channels

1 Number of TDM channels to transport in a stream

TDM Frames per Payload

160 Number of TDM frames per payload (packet)

Jitter Buffer Size (8 128 packets)

64 Configured jitter buffer size in packets

Computed Parameter Value Description Formula

TDM Channel Data Rate 64 kB/S Calculated TDM channel data rate in kB/S Number of TDM Channels x 64

Packet Payload Size 160 bytes Calculated payload size in each packet in bytes

Number of TDM Channels x TDM Frames per Payload

Packet Interval 20 mS Calculated packet interval (time between packets) in mS

Number of TDM Frames per Payload 8

Packet Rate 50 packets/S

Calculated packet rate for a stream in packets/S

(1 Packet Interval) x 1000

Jitter Buffer Delay 640 mS Calculated jitter buffer delay in mS

Note: This delay assumes a receive queue of half the jitter buffer size

Jitter Buffer Size x Packet Interval 2

Ethernet Frame Size 242 bytes Calculated Ethernet frame size in bytes = Packet Payload Size + Ethernet overhead (38 bytes no VLAN) + IP overhead (20 bytes IP + 8 bytes UDP + 16 bytes RTP)

Packet Payload Size + 38 + 44

Ethernet Stream Data Rate

96.8 kB/S Calculated Ethernet stream data rate in kB/S *

Ethernet Frame Size x Packet Rate x 8 1000

IP Packet Size 204 bytes Calculated IP packet size in bytes = Packet Payload Size + IP overhead (20 bytes IP + 8 bytes UDP + 16 bytes RTP)

Packet Payload Size + 44

Stream Data Rate 81.6 kB/S Calculated IP stream data rate in kB/S * IP Packet Size x Packet Rate x 8 1000

* In most instances, Ethernet overhead is stripped before the packet is transported over a WAN link. However, in certain instances (such as Metro Ethernet networks that transport the entire frame);

the Ethernet overhead is left on the packet.

2.2.9 Stream Statistics

NetXpress LX stream statistics are receiver-based. The time interval for collecting stream statistics is user-selectable (from 5-10 seconds for each stream). It is a good practice to review your stream statistics on a regularly scheduled basis (Section 4.3.6.1 Stream Statistics). You may be able to

modify your NetXpress LX system for optimum throughput, bandwidth efficiency, and reduced errors.

As an example, you may wish to alter the size of the jitter buffer if you are experiencing too many

lost, underrun, early, or late packets. Specifically, if you are experiencing too many late packets, you might need to increase the jitter buffer size.

2.3 System Security

System security is controlled through

Logon and password control.

Interface protocol management enabling and disabling.

An IP access list.


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Establishment and and control of SNMP Communities.

2.3.1 NetXpress LX Login

When you launch the Web server interface application, the system immediately displays the logon screen (Figure 2-2). You must type the proper user name and password to gain access to the NetXpress LX Web interface. Before it is configured, the NetXpress LX system has a default administrator user name of admin and default password of admin for the Web interface. Once you initially log on, you can change the Web interface administrator password, as well as administrator and guest accounts for Web FTP access (Section 4.3.7.1 Accounts).

Figure 2-2. NetXpress LX Web Interface Login

2.3.2 Management Protocols on an Interface

The NetXpress LX system comes with two Ethernet interfaces:

WAN

LAN

The LAN interface allows you to run all management traffic on a separate network if desired.

By default, each interface accepts HTTP and SNMP protocols and allows FTP and Telnet sessions to be established. You can use the interface screens in Section 4.3.4 Configure the Network to enable or

disable different protocols for each interface. Controlling protocols by interface enables you to

Tighten security

Block unwanted traffic

Ensure network privacy

2.3.3 IP Access List Use

You can add security to your NetXpress LX installation by limiting access based on specific IP addresses (Section 4.3.7.2 IP Access List). You can also use the same networking configuration screen to specify which interface can be used to gain access to the system.

2.3.4 SNMP Communities

An SNMP community is a group of hosts that you can manage as a distinct group with SNMP. You

must use a community name for all SNMP conversations to take place. You can use the same name for


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a read-only community and a read-write community, or you can specify two different names to restrict

write-access to the system.

2.4 NetXpress LX QoS

Quality of Service (QoS) / Class of Service (COS) mechanisms can reduce flow complexity by mapping multiple flows into a few service levels. Network resources are then allocated based on these service levels and flows can be aggregated and forwarded according to the service class of the packet.

2.4.1 COS Levels for Stream Data

The class of service (COS) level for a stream is established when the stream is created. The NetXpress LX system offers four COS levels (high, normal, medium, low) for stream data (Section 4.3.5.1 Stream Creation). The classes are based on service priority; the higher the priority, the more immediate the handling of the stream. For example, program audio is critical in many operations, so when a stream is configured for program audio, you designate a high class of service level for that

packet stream. Conversely, a voice circuit might be considered less critical to operations, so you might specify a lower COS level.

2.4.2 TOS Byte Marking for Outbound Stream Packets

In an IP network, all IP packets contain a field in the IP header called the Type of Service (TOS) byte. The value of the TOS byte tells the network what quality of service needs to be applied to the packet.

You can define what the value of the TOS byte field should be for each of the four classes of service supported by the NetXpress LX system for stream packets. The system places the appropriate TOS byte value corresponding to the COS provisioned for a stream in every outbound data packet for that stream (Section 4.3.4.3 Class of Service). Since TOS byte value can be set to any value per class of service, the NetXpress LX system can operate in networks using Differential Services (DiffServ) QoS and networks employing the standard TOS interpretation for QoS.

2.4.3 User-Defined TOS Byte Setting for Outbound SNMP and HTTP

Packets

In addition to supporting the TOS marking for stream data, the NetXpress LX system allows you to configure the TOS byte value placed in all outbound SNMP and HTTP packets. Therefore, SNMP

management traffic and Web interface traffic to be handled in the network with a different class of service than other packets.

2.5 NetXpress LX Internal TDM Busses

The NetXpress LX IP multiplexer uses two TDM busses to support data transfer for audio channels. These busses (TDM Bus 1A and TDM Bus 1B) can be configured to operate in T1 or E1 mode.

Note: Both A side and B side busses operate in the same mode; you cannot have a T1 bus and an E1 bus.

When set for T1 mode, the TDM busses support robbed-bit signaling. When set for E1 mode, the TDM busses in the NetXpress LX system support CAS (channel associated signaling) and CCS (Common Channel Signaling). With CAS signaling, time slot 16 is always reserved for telephone signaling. The

data rate is fixed at 1.544 MHz (T1 mode) or 2.048MHz (E1 mode). In E1 mode, you can enable or disable signaling.

2.5.1 Compatibility with Intraplex TDM Channel Modules

Nearly all Intraplex TDM channel modules are compatible with the NetXpress LX multiplexer. Table 2-2 shows currently supported modules.


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Table 2-2. NetXpress LX-supported TDM Channel Modules

Module

Nominal Power

(watts)

Module

Nominal Power

(watts)

Module

Nominal Power

(watts)

Hig

h F

ideli

ty P

rog

ram

Au

dio

Mod

ule

s

An

alo

g I

np

ut/

Ou

tpu

t

PT-150A 4.7

Hig

h F

ideli

ty

Pro

gram

Au

dio

Mo

du

les

AE

S\E

BU

In

pu

t /

Ou

tpu

t

PT-D150 4.7

Data

Mod

ule

s

DA-191A 1.2

PT-150B 4.0 PR-D150 6.6 DA-191B 1.2

PT-150C 4.0 PT-D350 3.0 DA-91A 1.0

PR-150A 6.6 PR-D350 3.4 DA-91i 1.0

PR-150B 6.0 PT-D355 3.0 DS-64NC 2.5

PR-150C 6.0 PR-D355 3.4 D-100 3.0

PT-153 5.5

Vo

ice M

od

ule

s f

or E

1 VF-15E 2.3 DS-562i 2.0

PR-153 5.5 VF-16AE 2.3 DS-961D 1.2

PTR-155 5.0 VF-16E 2.3 DS-961DE 1.2

PT-250 3.0 VF-25E 2.0 DS-961DF 1.2

PR-250 3.4 VF-27E* 2.0 DS-961DG 1.2

PTR-255 7.7 VF-28E 2.0 DS-965 1.2

PT-350 3.0 VF-29E 2.0 DS-966A 2.5

PT-350B 3.0

Vo

ice M

od

ule

s f

or T

1

VF-15 2.3 DS-967 2.5

PT-350C 3.0 VF-16 2.3 OCU-DP 2.0

PR-350 3.4 VF-16A 2.3

PR-350B 3.4 VF-25 2.0

PR-350C 3.4 VF-27* 2.0

PT-353 3.0 VF-28 2.0

PR-353 3.4 VF-29 2.0

PT-355 3.0 VF-40 2.0

PT-355B 3.0

Secu

re

Dig

ital

Vo

ice

Mo

du

les

DV-600 5.0

PT-355C 3.0

DV-600A 5.0

PR-355 3.4

PR-355B 3.4

PR-355C 3.4

* Neither the VF-27 nor VF-27E module supports or operates with E & M signaling when used in a

NetXpress LX system.

You must configure each channel module to use either TDM Bus 1A or TDM Bus 1B. Also, if the TDM busses are set for E1 operation, you must provision the bus itself to use CAS signaling and then

provision each module on the bus to inform it that CAS signaling is in use. Each TDM bus has its own frame loss signal to tell the modules to mute if there is a problem with the arriving data intended for that particular bus.


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2.5.2 TDM Channel Loopbacks

Figure 2-3 shows the normal/default of no loopback and the three Time Division Multiplexing (TDM)

channel loopback scenarios for channel modules and TDM busses: internal, external, and both.

Figure 2-3. TDM Loopback Scenarios

When you apply the internal loopback to a time slot or a group of time slots on the TDM bus, the channel module data is copied back to the receive channel on that same TDM bus, as well as being transmitted to its IP targets. When you apply the external loopback to a time slot or a group of time

slots on the TDM bus, the received data is delivered to the channel module on that same TDM bus as well as being transmitted back out to its originating source. You can apply both internal and external loopbacks simultaneously. This example shows loopbacks for an entire bus. However, you can also loopback individual time slots within a bus.

2.5.3 TDM Bus Mapping

The NetXpress LX or CM-30 TDM bus is connected by default to a virtual IP bus; this connection is bi-directional. The TDM bus mapping feature allows you to reconfigure your connections to suit your needs. You can connect a time slot from TDM A, TDM B, or either of the echo cancellers to the corresponding time slot on any of the 4 IP ports. You can connect a time slot from TDM A or TDM B to

the corresponding time slot on either of the echo cancellers.

The NetXpress LX system (or CM-30 module) has 2 bus map choices:

The pre-configured default map has both TDM A and TDM B busses mapped from IP sources to

two (multi-unicast) IP destinations (connections).

You can select the User Defined Profile and create a customized bus map configuration. For example, you can create a multi-unicast configuration, where one source is connected to more than two destinations. Section 4.3.3.4 TDM Bus Mapping Configuration gives additional multi-unicast information.


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2.6 System Time-of-Day

With the NetXpress LX system, there are two ways to set the system time-of-day: 1) manually and 2) via NTP (Network Timing Protocol) server. If you choose the latter method, you must use the Web server interface to enable NTP in the NIM Configuration General Setup screen and provide the IP address of the SNTP server (Section 4.3.3.1 General Setup). The NetXpress LX system maintains the time and date in a battery-backed time-of-day clock on the CM-30 module.

2.7 System Timing

2.7.1 Types of System Timing

System timing is the process of synchronizing communications and stream traffic between two or

more NetXpress LX systems in a network. Time synchronization is critical to the proper functioning of the NetXpress LX network. It must be configured correctly.

The primary timing source for all interconnected NetXpress LX systems should trace back to the same long-term accurate oscillator.

Primary and secondary timing are configured via the Web interface using the System Timing screen (Section 4.3.3.5 System Timing). You must specify the timing source for both primary and

secondary timing. If the primary timing source is unavailable, the system uses secondary timing. The NetXpress LX system provides four timing sources from which to choose:

Internal

External

Stream

SynchroCast

Timing can be sourced through the RS-422 Timing OUT port on the MIU-201 or MIU-202-2 to feed

additional multiplexers.

2.7.1.1 Internal Timing

Internal timing is derived from an extremely accurate internal oscillator on the CM-30 module. In a NetXpress LX network, only the master NetXpress LX system can use internal timing. Other NetXpress LX shelves in the network must use external, stream, or SynchroCast timing derived from the network master.

2.7.1.2 External Timing

External timing is usually a precision timing signal derived from an external device that is traceable to a stratum-1 timing source (for example, a public network WAN interface such as T1 or E1). External timing is input through a connection to the Timing IN port on the MIU-201 or MIU-202-2. The external timing input accepts an RS-422/RS-485 balanced clock signal. If external timing is selected as the primary timing source on the master NetXpress LX system, external timing, stream, or SynchroCast

timing must be selected as the primary timing method for the subordinate NetXpress LX systems.

2.7.1.3 Stream Timing

Stream timing is derived from the incoming packet stream. A timing stream must have a packet rate of 8 packets per second or greater (1000 frames/packet or less). This type of timing uses an algorithm inherent in the TDMoIP chip. In a NetXpress LX network, only subordinate NetXpress LX systems can

be set to stream timing mode. The NetXpress LX master system monitors stream traffic and adjusts timing so that the subordinate shelves are synchronized with the master clock frequency. As a general rule; the faster the packet rate, the better the stream timing. With stream timing, jitter buffer size can be monitored and regulated to avoid buffer underflow/overflow and negate the effect of packet delay


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variation. When a subordinate system derives timing from the master, clock recovery algorithms are

employed to align clock frequency and control packet jitter/wander. Also, in order to recover timing from a stream, the stream must be active and sending. Networking or router problems can result in no timing recovery from a stream.

Note: When you configure several receive streams and use a stream as the timing source, you should use the stream with the highest packet rate (such as the lowest frames per payload value) as the primary timing stream.

2.7.1.4 SynchroCast3 Timing

The SynchroCast3 system uses a simulcast technique which transmits to an extended geographic area using multiple, overlapping transmitters operating on the same frequency. Historically, broadcasts

from nearby transmitters on the same frequency have created serious reception problems where they overlap. The SynchroCast system, originally developed for use in land mobile radio systems, makes simulcasting possible in FM broadcast as well. The SynchroCast system can provide dramatically

increased station coverage while reducing or eliminating unwanted artifacts at the listeners receiver.

The SynchroCast3 system in the NetXpress LX multiplexer maintains the phase alignment of the transmitted signals using Global Position System (GPS) technology, providing

GPS controlled carrier frequency synchronization.

GPS controlled precision audio phase alignment.

Dynamic adjustments to compensate for network routing changes.

The SynchroCast3 system sends timing reference signals along with the audio content to the transmitter sites. GPS receivers, placed at the Origination Point and transmitter sites, provide a timing reference. At the Transmitter, timing signals coming from the Origination Point (along with the audio content), are compared with the local timing reference and a precise amount of delay is introduced to

correct the timing difference between transport paths. Once the signals are synchronized, the system operates automatically to keep the preset delay constant. The Intraplex SynchroCast3 System Installation and Operation Manual gives more information on the SynchroCast3 system.

The SynchroCast3 system carefully controls the receive jitter buffers associated with the IP streams, allowing multiple locations to deliver their stream data at precisely the same instant. This control is essential for radios using multiple transmitters so that interference problems associated with them can be minimized.

2.7.2 NetXpress LX Timing Scenarios

In a system that utilizes multiple NetXpress LX units deployed on an IP network, it is important to maintain consistent synchronization of the internal NetXpress LX system clocks. This synchronization ensures that any NetXpress LX system can receive streams generated by any other unit or a combination of streams from any other units (Figure 2-4).


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Figure 2-4. Timing Synchronization

NetXpress LX units can derive system timing in one of four ways:

1. An internal clock is available, based on a local oscillator within the unit (Internal Timing).

2. An external clock can be applied to the unit (External Timing).

3. An incoming IP unicast or multicast stream (Stream Timing), thereby synchronizing itself to the NetXpress LX unit that generated the stream.

4. SynchroCast, which incorporates a blend of Stream and External timing from GPS receivers.

Simple point-to-point systems commonly use a combination of internal and stream timing. Figure 2-5 shows the unit at site A set to internal timing, utilizing its local internal oscillator. The unit at Site B

derives timing from the audio stream transmitted from Site A to Site B.

Figure 2-5. Point-to-Point Timing Synchronization

The configuration advantage in Figure 2-5 is simplicity of implementation. No external timing sources are required. This configuration can be extended to multiple site systems by designating one site as the master timing location and having the rest of the sites derive timing from that site. Figure 2-6

shows such a system, with Site A using internal timing and the remaining sites using stream timing to achieve synchronization to Site A.

NetXpress LX

A

NetXpress LX

B

INTERNAL TIMING

STREAM

TIMING

NetXpress LX

A

NetXpress LX

B

NetXpress LX

D

NetXpress LX

C

Multicast Audio

Stream 1

Audio Stream 2

NetXpress LX units at sites A and C must have synchronized system clocks so that the NetXpress LX unit at site D can properly receive and process its two incoming audio streams.


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Figure 2-6. Stream Timing Synchronization

This method of timing distribution can be very simple and efficient in cases where programming streams are emanating from one master site to all the remaining sites. However, programming may be generated at multiple sites within the network, and these program source sites may not all receive program streams from the master site that can be used as timing sources (Figure 2-7). In this example, Site A is the master timing source, but Site C does not receive a stream from Site A and

therefore cannot synchronize its outgoing stream to the rest of the network. As a result, the two streams received at Site D utilize different synchronization sources and cannot be properly received and decoded.

Figure 2-7. Streams with Different Synchronization Sources

There are two possible solutions to this situation.

1. Receive a stream at site C from Site A solely for the purpose of synchronization (Figure 2-4). The cost of this solution is the additional bandwidth required in the network end-link to site C.

2. An alternative approach would be to utilize highly accurate external timing sources at Sites A and C to achieve network synchronization. One example would be a Stratum 1 traceable timing signal

NetXpress LX

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NetXpress LX

B

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C

Internal Timing

Stream Timing

Internal Timing

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B

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C

Internal Timing

Stream Timing

Stream Timing

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D

Stream Timing

Sites B, C, and D use stream timing to derive timing from master Site A.

Site D cannot process both incoming streams because they have different timing sources.


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from a telecom network provider. Another source of accurate external timing signals is a GPS

receiver, using GPS timing at the stream timing sites (Figure 2-8). This solution guarantees the two streams received at site D have compatible timing, allowing Site D to time from either incoming stream.

Figure 2-8. Timing Synchronization with GPS

In this case, the fixed cost of purchasing and deploying GPS units at Sites A and C can be traded against the recurring cost of bandwidth to receive a timing stream at Site C.

2.7.2.1 Backup Timing

In networks that generate revenue-critical programming, it may be prudent to design backup timing scenarios. Each NetXpress LX unit can be programmed to switch to an alternative timing source in the

case of primary timing signal loss. If the primary timing source is an incoming stream, for example, the secondary source could be a different stream; either an audio stream or a dedicated timing stream. Another scenario could use Stratum-1 or GPS as the primary timing source with stream timing as the backup. Once again, the trade-off would be the one-time cost of GPS receivers or Stratum-1 timing sources versus the recurring cost of bandwidth for the backup timing signal. If both the primary and secondary timing sources fail, the NetXpress LX unit falls back to internal timing.

Sites that are receive-only can usually utilize stream timing since they only need to be synchronized during the time they are receiving a stream. If receive streams at a receive-only site are changed frequently, there could be an operational advantage to using external (stratum-1 or GPS) timing, in that the operator would not need to consider whether or not a receive signal is present.

Certain receive sites may also generate off-air monitor streams back into the network (Figure 2-9). A

logical choice for timing in this network would be to use internal timing at Site A and stream timing at Sites B and C. In this case, if the audio stream to Site C is lost, the monitoring stream back from Site

C is not properly timed for reception at other network sites, which can result in periodic jitter buffer underflow or overflow at the receiver with each event causing a brief interruption or audio glitch. If it is important to maintain smooth continuous reception of this off-air monitoring stream during periods of primary stream loss, an external timing source or a backup timing stream is needed at Site C.

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External Timing External Timing

Site D can derive system timing from either incoming steam.

GPS

Stream Timing

GPS


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Figure 2-9. Timing with Off-Air Monitor Streams

2.7.2.2 Timing Summary

NetXpress LX units that generate streams into the network should share a common timing reference to guarantee that any NetXpress LX unit can receive or monitor any stream in the network. You can use stream timing, external (Stratum-1 or GPS) timing, or a combination of the two. In cases where audio streams are already present and can be used as timing sources, stream timing is essentially

free. If a dedicated timing stream must be added, the recurring cost of the stream bandwidth can be traded off against the one-time cost of implementing GPS receivers.

You should also consider timing failure scenarios. Ideally, a fallback timing source should be available at each site that keeps that site in synchronization with the other sites even if its primary timing source fails. Once again, the backup source can be either a stream or an external input (Stratum-1 or GPS) with the corresponding cost trade-off.

2.8 NetXpress LX System and FEC

The NetXpress LX system maintains uninterrupted audio transport by supporting Forward Error Correction (FEC). Specifically, the NetXpress LX system supports RFC 2733. Forward error correction is the process obtaining error control in data transmission in which the source (transmitter) sends

redundant data and the destination (receiver) recognizes only the portion of the data that contains no apparent errors.

An FEC packet is a special type of RTP packet. It is constructed by placing an FEC header and FEC payload in the RTP payload.

In the NetXpress LX system, up to 32 streams (16 in each direction) can be designated as FEC streams. For each of the FEC streams, you can specify either of two techniques for forward error correction: FEC LOW or FEC HIGH (Section 4.3.5.1 Stream Creation). This specification affects the

sender only. The receiver processes all FEC packets.

FEC LOW (appropriate for most low packet loss conditions)

Single error correction is engaged. This scheme introduces a 50% overhead (increased bandwidth required) and can correct all single packet losses consecutive packets are not lost.

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Audio Stream

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Stream Timing

Stream

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Monitor

Stream

Monitor

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Audio Off-air monitor

audio

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audio


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FEC HIGH (used in more serious packet loss conditions)

Triple error correction is engaged. This scheme introduces a 100% overhead (increased bandwidth required) and can correct one, two, or three consecutive packet losses. In this scheme, the packet sequence sent is critical if it is to protect against consecutive packet losses.

Table 2-3 shows the NetXpress LX performance data, with an overall loss rate and a percentage of high versus low FEC loss.

Table 2-3. NetXpress LX FEC Performance Data

Network Loss Rate (%)

High FEC Loss (%)

Low FEC Loss (%)

1 0.0017 0.027

2 0.0023 0.085

3

4

5 0.0168 0.507

6

7

8

9

10 0.14 2.1

11

12

13

14

15 0.597 4.87

% High FEC Loss ((Lost packets / Rx packets) x 2) x 100 % Low FEC Loss ((Lost packets / Rx packets) x 1.5) x 100

2.9 Power

The system runs on either AC or DC power supplies. The NetXpress LX-100 multiplexer supports 30 W AC powered. The NetXpress LX-300 multiplexer supports 60 W and 95 W AC powered or 50 W DC

powered supplies.

The NetXpress LX-300 system also supports redundant power supplies. You c

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Intraplex® NetXpress™ - Simulcast Solutions · 2.10.1 RBS ... 2.12 Configuration Files Backup and Restoration ... 3.3 Wiring & External Connections