Test Legacy and Next Generation Hybrid Networks

Welcome to another GL Communications' newsletter providing information about our testing solutions for legacy and next generation hybrid networks.

GL can test legacy and next generation networks simultaneously through one self-contained platform. This platform is a 1U rack chassis that houses several interfaces for network testing including VF, FXO and FXS, T1 E1, Datacom, and Ethernet ports. This platform can analyze and emulate traffic traversing these links. For example, perform bit error rate testing, send, and receive tones, digits, audio files, packets and more. The platform can also monitor and record traffic by being placed in-line on a network.

Full T1 E1
Fractional DSO
Datacom (DCE and DTE)
2-Wire FXO, FXS
4-Wire VF
Packet/Ethernet 10/100/1000/10000
- OC3/STM1, OC12/STM4
- OC48/STM16, OC192/STM64
- T3 E3


Hybrid networks, consisting of TDM and Ethernet interfaces, are widely found in mission critical networks such as air traffic control networks. This is because the legacy technology is still reliable, and the infrastructure is already in place to service these traffic flows. More modern technologies such as Ethernet are designed to complement rather than replace these legacy networks. TDM and Ethernet can both be used for voice communications traffic. Therefore, network engineers and technicians need a platform versatile enough to test hybrid networks.

GL’s network test equipment can be conveniently stored in a 1U rack enclosure and therefore easily deployed into a server room or lab environment. In the picture shown, we have placed the tProbe + Datacom board and the PacketExpert into such an enclosure. The tProbe can test TDM and Datacom interfaces whereas the PacketExpert can test Ethernet up to 10 Gbps.

Also included in the 1U rack enclosure is a single board computer which controls the tProbe and PacketExpert. This single board computer will come pre-installed with all required GL software to fully control the hardware. The single board computer is accessible both locally (through HDMI and USB ports) and remotely (through an Ethernet management port) via remote desktop protocol.

Basic network tests include bit error rate testing, sending, and receiving digits, tones, audio files and packets (up to UDP layer). Measure bit error rates, latency, packet loss, throughput, jitter and more.

GL’s test tools have recently been enhanced to support voiceband measurements such as Signal-to-Noise Ratio and Level, Three Tone Slope (Gain Slope), Signal-to-C-Notched Noise Test, Attenuation Distortion, 1004 Hz tone, Intermodulation Distortion, Impulse Noise and Voice Quality measurements (computation of the mean opinion score for voice calls). These tests are available on the 4-wire VF, 2-wire FXO FXS, and T1 E1 ports of the tProbe.

For the Ethernet interfaces, more advanced testing includes RFC 2544 for measuring layer 1 or layer 2 devices (cables and switches), RFC 6349 (for TCP throughput testing) and ITU-T Y.1564 for verifying service level agreements.

The systems can be placed in-line on a network in a tap configuration and can therefore record and analyze the traffic passing through. GL provides analysis tools for a wide range of voice and data protocols.

GL can also test SONET/SDH and T3 E3 networks using the SonetExpert and the T3 E3 Analyzer, respectively. These testing platforms can also be placed in the 1U rack enclosure and controlled by the single board computer. This gives full flexibility to the customer to choose the interfaces that they are most interested in testing. For example, any combination of 3 of the tProbe + Datacom board, PacketExpert, SonetExpert and T3 E3 Analyzer can be placed in the 1U rack enclosure.

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