SONET & SDH optical testing

OC-3/STM-1 and OC-12/STM-4 Analysis and Emulation

Direct Access to T1 E1 DS0 on OC-3/12 STM-1/4 on LightSpeed1000™


Voice, data, and video traffic is exploding as smartphones, IP TV, video streaming, and "cloud" based services takeoff.  A majority of the backbone transport for these applications continues to be SONET and SDH optical transmission networks.  A dominant protocol for IP transport is PoS (Packet over SONET) and another is ATM (Asynchronous Transfer Mode).  Both schemes are packet based, with ATM using fixed size packets of 53 bytes called "cells", and PoS using variable packet sizes closely matching to Ethernet frames. 

SONET and SDH transmission network also continue to be used for conventional channelized traffic – carrying many TDM T1, E1, T3, and E3 pipes.

GL's LightSpeed1000™ hardware platform (PCIe Card and USB Pod) is capable of OC-3/12 and STM-1/4 wire-speed processing on quad optical ports for functions such as wire-speed recording and wire-speed playback of Unchannelized and Channelized ATM, PoS, and RAW Traffic.

Two ports out of the 4 ports are meant for SONET/SDH unchannelized and unframed data. The remaining two ports are meant for SONET/SDH channelized data of carrying many independent unframed/framed T1, E1, T3, and E3 streams.

The LightSpeed1000™ comes with software for overall monitoring, BERT, emulation, and protocol analysis with a price tag that compares very favorably with similar test instruments at three times the price.

In an OC-3/STM-1, all 84 T1s or all 63 E1s can be identified and processed in transmit and receive modes. In an OC-12/STM-4, all 336 T1s or all 252 E1s can be identified and processed in transmit and receive modes. The hardware can also be easily configured / programmed for delaying of ATM Cells or PPP packets.

GL Communications has the following variants of OC-3/STM-1 and OC-12/STM-4 Analyzers:

  • Quad OC-3/STM-1 and OC-12/STM-4 PCI-Express card (Windows® 7 and above 32-bit, 64-bit)
  • Portable Quad OC-3/STM-1 and OC-12/STM-4 Unit (Windows® 7 and above 32-bit, 64-bit)

The card's multiple connectivity using PCIe, Gigabit Ethernet (GigE), USB 2.0 and onboard DDR2 memory makes it suitable for many applications.

Multiple cards are possible in a PC for analysis of four or more directions simultaneously. USB 2.0 interface is used to connect with a Notebook PC for portability. GigE Ethernet ports for testing RAW, BER, RFC2544, RAW SONET/SDH, and Ethernet bridge applications. The hardware is firmware FPGA based making it easy to upgrade in the field for application versatility.

A unique feature of the card is the capability to capture, transmit and process at wirespeed to/from applications and hard disk on all interfaces. An API Toolkit allows users to develop specialized applications.

Please visit LightSpeed1000™ for more details.

Main Features

  • Allows to configure the number of T1 E1 channels to be Multiplexed/Demultiplexed to / from OC-3/12  STM-1/4
  • 2 Channelized OC-3 STM-1/OC-12 STM-4 SONET/SDH interfaces per Lightspeed1000™ card
  • 2 Unchannelized OC-3 STM-1/OC-12 STM-4 interfaces per Lightspeed1000™ card 
  • Allows direct access to anything and everything on SONET / SDH – Framing and Payload, including structured traffic (T1, E1, STS-1, DS3 etc) or unstructured traffic (ATM, PoS, etc).
  • Supports all  "basic applications" and "special applications" for T1 or E1 channels
  • Comprehensive analysis / emulation of voice, data, fax, protocol, analog, and digital signals, including echo and voice quality testing
  • Supports BERT, and Capture and Playback applications
  • Supports Protocol Analysis of structured protocols – HDLC, ISDN, CAS, and more.
  • Direct access to any or all T1s and E1s
    • 2 x 336 T1’s x 24 DS0s = 16,128 DS0s
    • 2 x 252 E1’s x 30 DS0s = 15,624 DS0s
  • Scans the received STM-4/STM-1 traffic and identifies the mapping, tributary type [T1/E1], equipped/unequipped status of the tributaries
  • Broadcasts the selected T1/E1 channel data on all the 252 E1’s or 336 T1’s
  • Supports any combination of DS0/64/56/16/8 kbps fractional T1/E1, and N x T1/E1 interface definitions (a total of 252 E1s or 336 T1s – in each port )
  • Supports multiplexing multiple T1 or E1 channels to a single channelized OC-3/12 STM-1/4 line
  • User configurable OC-3/12 STM-1/4 mapping – allows user-defined T1 and E1 channels to multiplex. The channel numbering is same as in demultiplexer
  • User configurable idle code to fill the channels when the user added channels do not have data to multiplex.
  • Unused channels will be treated as unequipped.

Comparison of Channelized OC-3/STM-1 Test Solutions

The above image depicts 2 solutions for testing channelized OC-3/STM-1 lines. The first solution shows an external multiplexer and demultiplexer hardware providing the channelized information to multiple T1 E1 access cards such as GL’s Octal T1 E1 cards for analysis and emulation. This solution would require multiple PCs, T1 E1 access cards, and numerous cables adding to the cost and complexity of the entire solution.

A more simpler solution is provided by GL’s Channelized LightSpeed1000™ board, which supports direct access to all or user-defined 2 x 336 T1s or 2 x 252 E1s per card for analysis and simulation – all within a one pc. With this hardware, any combination of DS0/64 kbps, fractional T-1/E-1, and N x T1/E1 interface definitions can be accessed for performance monitoring.

SONET/SDH Data Rates

  • SONET is the North American standard (termed OC-N) defined in Telcordia GR-253-CORE and ANSI T1.105. STS-1 (Synchronous Transport Signal Level -1) is the basic level of electrically framed signal format in SONET. Higher-level signals are integer multiples of STS-1, creating the family of STS-N signals, for N = 1, 3, 12, 48, 192 & 768.  The optical counterpart for each STS-N signal is designated as OC-N (Optical Carrier level-N).
  • SDH is the Asian and European standard (termed STM-N) defined in ITU G.707 and G.708 standard. An STM-N (Synchronous Transport Module Level-N) are the frame structures used in the SDH.
  • The following table details bit rates of SONET and SDH.
North American Standards ITU-T Designation    

Electrical Level

Optical Level

Data Rate (Mbps)

Payload Rate (Mbps)

SDH Equivalent

T1 Equivalent







28 T1s







84 T1s







336 T1s







1344 T1s







5376 T1s





















86016 T1s


SDH Mapping in GL’s LightSpeed1000™

The below diagram depicts various T1/E1 to STM-1 signal mapping possibilities in SDH. The paths colored in green are currently supported on the GL’s LightSpeed1000™ hardware.

Various T1/E1 mappings in SDH:

  • STM-4 --> STM-1 --> AU-3 --> TUG-2 --> TU-12 --> E1
  • STM-4 --> STM-1 --> AU-4 --> TUG-3 --> TUG-2 --> TU-12 --> E1
  • STM-4 --> STM-1 --> AU-3 --> TUG-2 --> TU-11 --> T1
  • STM-4 --> STM-1 --> AU-4 --> TUG-3 --> TUG-2 --> TU-11 --> T1

SONET Mappings in GL’s LightSpeed1000™

The below diagram shows various T1/E1 to OC-3/12 mapping possibilities in SONET. The paths colored in green color are supported on the GL’s LightSpeed1000™ hardware.

The T1 and E1 mappings for OC-3 in SONET are as below:

  • STS-12 --> OC-12 --> STS-3 --> STS-1 --> VT-Group --> VT2 --> E1
  • STS-12 --> OC-12 --> STS-3c --> STS-1 --> VT-Group --> VT2 --> E1
  • STS-12 --> OC-12 --> STS-3 --> STS-1 --> VT-Group --> VT1.5 --> T1
  • STS-12 --> OC-12 --> STS-3c --> STS-1 --> VT-Group --> VT1.5 --> T1


Accompanying Basic Software / Features

Almost all the basic applications and optional applications supported by T1 E1 analyzers are also supported by Channelized LightSpeed1000™. For example, capturing and transmitting an entire raw OC3 / STM1, and OC12 / STM4 RAW signals simultaneously, or performing ISDN, or SS7 analysis, can be performed using the software accompanying the channelized LightSpeed1000™.

A list of all the basic applications and other optional applications (requiring additional licenses) are listed here.

Some of the applications currently supported are discussed below -

Application #1: Protocol Analysis

The protocol analysis can be performed on the packets captured non-intrusively by connecting the channelized Rx Ports of LightSpeed1000™ to a Fiber Optic tap to as shown below. The LightSpeed1000™ is capable of selectively identifying and forwarding the T1, or E1 signals from OC-3/12  STM-1/4 signal streams to GL’s wide variety of protocol analysis modules such as SS7, ISDN, CAS, and more.

Tapping Optical Lines for Channelized Protocol Analysis

Application #2: Abis Monitoring

Application #3: ATM to SDH in a 3G GSM Network



  • High Performance x4 PCIe Compliance with optimized DMA to perform Rx and Tx packets to/from PC memory.
  • 4 Optical Ports
    • 2 Unchannelized Ports (STM-1/OC-3 and STM-4/OC-12)
    • 2 Channelized Ports (STM-1/OC-3)
  • 1 USB 2.0 Port

Alarm LEDs:

  • LOS – LOS (Loss of Signal) is a physical layer error, which indicates loss in optical signal.
  • LOF - LOF (Loss of Frames) becomes active when receiving interface detects errors in the framing pattern for three milliseconds. This will be indicated using the frame alignment bytes A1 and A2. LOF is cleared when two consecutive valid A1/A2 framing patterns are received.
  • User – A user-defined LED can be configured by the user as per the requirements.

Bus Interface:

  • PCIe Specification 1.2 Compliant

Power and Dimensions:

  • 4.2” x 9.2”
  • +12 volts, 3.5 Amps


  • Structured (T1, E1. DS0)
  • Unstructured (OC-3/STM-1, OC-12/STM-4)
  • Transparent Generic Framing Procedure (GFP) (Raw)
  • Hardware Filters to filter out and allow only traffic of interest

Regulatory and Compliance

  • Telecom (OC3): Telcordia GR-253 (SONET)
  • ITU-T G.707 (SDH) , G.783 (03/06)

Channelized Protocols (Structured)

  • High-Level Data Link Control (HDLC)
  • Point-to-Point Protocol (PPP), RFC 1662
  • Multilink PPP (MLPPP), RFC 1990
  • Frame Relay, RFC 1490
  • Multilink support over Frame Relay (FRF.12) and MLPPP
  • SS7, ISDN, CAS, SS1, SSM
  • V5.x, DCME, FDL (T1 Interface only)

UnChannelized Protocols (Unstructured)

  • Packet Over Sonet/SDH (PoS) compliance - RFC 2615(1619)/1662
  • ATM User Network Interface (UNI) Specification and the ATM physical layer for Broadband ISDN according to CCITT Recommendation I.432


  • Internal or Recovered
  • Hardware based precise time-stamping of cells with 10 nsec resolution, 1 ppm accuracy.

Functional Specifications

Support for Channelized OC3 to T1, Channelized STM1 to E1, full, fractional, or channelized T1/E1
Up to 84 T1 per port (or 2* 84 = 168 T1s per card)
Up to 63 E1 per port ( or 2* 63 = 126 E1s per card)
SONET multiplexing:
OC3 -> STS-3 -> STS-1 -> VTG -> VT1.5 -> T1 -> N x DS-0
OC3 -> STS-3 -> STS-1 -> VTG -> VT2-> E1 -> N x DS-0
SDH multiplexing:
STM1 -> AUG -> AU-4 -> VC-4 -> TUG-3 -> TUG-2 -> TU-12 -> VC-12 -> E1
STM1 -> AUG -> AU-4 -> VC-4 -> TUG-3 -> TUG-2 -> TU-11 -> VC-11 -> T1
STM1 -> AUG --> AU-3 -> VC-3 --> TUG-2 --> TU-12 -> VC-12 --> E1
STM1 -> AUG --> AU-3 -> VC-3 --> TUG-2 --> TU-11 -> VC-11 --> T1

Physical Layer Alarms and Error Counts

Alarms - Loss of Light (LOL), Loss of Signal (LOS), Out of Frame (OOF), Loss of Frame (LOF), Alarm Indication Signal (AIS), Remote Defect Indication (RDI), and Automatic protection switch byte failure (APSBF)

  • Line, Path, and Section error counts - Bit-Interleaved Parity (BIP), Remote Error Indication (REI)
  • FCS, Rx / Tx Abort, and MIN / MAX Length

Sync Loss, HDB3 Violation, Carrier Loss, Frame Error, Remote, Distant MF, AIS,
BPV Errors, CRC Errors, Frame Errors, Transmit Under Run, Receive Over Run

Loopback Capabilities

  • Line, Diagnostic, and PL3 Loopback at SONET SDH level
  • Software loopback at T1/E1 levels

Monitoring Applications

For T1/E1

  • Byte Values, Binary Byte Values, Signaling Bits, DC Offset, Frequency,
  • Power Level, Multi-frame Data, Timeslot Displays, ASCII Timeslot Display,
  • Oscilloscope and Spectral Displays provide graphical analysis of signals


  • Monitoring Alarms and Error Counts

Intrusive Test Applications

For T1/E1

  • Bit error rate testing (BERT) pattern generation and detection per channel
  • Transmit Tone, Transmit Gaussian Noise, Transmit Multiframe
  • Transmit Signaling Bits, and Rx-to-Tx loopback


Item No Item Description
LTS100 Lightspeed1000™ - Dual OC-3/12 STM-1/4 PCIe Card


Any 16 Ports Chan  Lic for OC3/12, STM1/4, n=1
Any 32 Ports Chan Lic for OC3/12, STM1/4, n=2
Any 48 Ports Chan Lic for OC3/12, STM1/4, n=3
All Ports Chan Lic (84x2 for T1, 63x2 for E1), n=5
All Ports Chan Lic (84x4 for T1, 63x4 for E1) (n = 6)

  Channelized Analysis and Emulation Applications
Basic Capability to Rx/Tx RAW OC3 / STM1
Basic Capability to Rx/Tx RAW OC12 / STM4
Record Playback RAW OC3 / STM1
Record Playback RAW OC12 / STM4
  Related Accessories and Cables (LightSpeed1000™)
IPN1310a SFP Transceiver for for OC-3/STM-1 and OC-12/STM-4  Optical, Duplex LC, Single-Mode, 1310nm, IR (Intermediate Range, 15 km)

SFP Transceiver for OC-3/STM-1 and OC-12/STM-4 Optical, LC, Multi-Mode, 850 nm or 1310 nm


1 Gbps / 10 Gbps Fiber Optic Cable, Single-Mode, Duplex LC to Duplex LC
1 Gbps / 10 Gbps Fiber Optic Cable, Single-Mode, Duplex LC to Duplex SC
1 Gbps / 10 Gbps Fiber Optic Cable, Multi-Mode, Duplex LC to Duplex LC
1 Gbps / 10 Gbps Fiber Optic Cable, Multi-Mode, Duplex LC to Duplex SC
40G / 100G  Fiber Optic Cable, Multi-Mode  
40G / 100G  Fiber Optic Cable, Single-Mode

SA019st Fiber Optic T-tap, Duplex LC, Single-Mode; includes one SA019a; requires one SA019sc
SA019sc Fiber Optic Analyzer Cable (Special ’Y’ Cable), Single-Mode, Duplex LC to Dual Duplex LC, 3m, Special Analyzer Cable for use with SA019st
SA019mt Fiber Optic T-tap, Duplex LC, Multi-Mode; includes one SA019c; requires one SA019mc
SA019mc Fiber Optic Analyzer Cable (Special ’Y’ Cable), Multi-Mode, Duplex LC to Dual Duplex LC, 3m, Special Analyzer Cable for use with SA019mt

1GB Fiber Optic Single-Mode T-tap Kit with Required Cables and SFP Transceivers


1GB Fiber Optic Multi-Mode T-tap Kit with Required Cables and SFP Transceivers