Tunnel Telephone and Ethernet Access Application Solution

1. Requirements

A tunnel has 15 chain-distributed branch access points, each requiring 2 telephone lines and 2 physically isolated Ethernet connections, with approximately 2 km between branch nodes; the central end aggregates 30 telephone lines and Ethernet services.

2. Network Topology Diagram

Based on these requirements, the central end is configured with the IDM-MP200-30EN; the remote end is configured with the IDM-NTD421 device.

At the central end, the IDM-MP200-30EN device is configured with 30 telephone lines, connecting to the PBX digital program-controlled switch, and 2 Ethernet ports connecting to the office network switch and the surveillance network switch respectively.

The IDM-NTD421 device, depending on the traffic at each node, requires 1 or 2 office telephone lines, with the office network and surveillance network connected to the first and second Ethernet groups respectively.

Note: The IDM-NTD421 device has 4 Ethernet ports, which can be configured as 2+2 isolation or 1+3 isolation, customized before shipment.

The network topology diagram is as follows:

3. Device Introduction

The IDM-NT421 Optical Terminal extends data services to various user areas, serving as a replacement for remote small offices, enabling cross-boundary number assignment, and alleviating the load on switching offices; or in urban areas, it overcomes the limitations of twisted-pair cables in bandwidth and transmission distance, expanding the service range of switching offices. This device is widely used in public telephone network access and dedicated line information transmission for telecommunications data services, power utilities, banking, public security, military, schools, highways, and other sectors.

Product Features:

• Single optical port, optical line transmission rate of 250 Mbps;
• 4 Ethernet interfaces, each pair sharing 1 physically isolated 100 Mbps line-speed Ethernet;
• Provides two central-end telephone interfaces (FXO), or two remote-end telephone interfaces (FXS), or magneto telephone (MAG);
• Provides two half-duplex RS485 interfaces, or one full-duplex RS422 interface;
• Can form point-to-point, chain network, and other network topologies.

4. Device Selection Table

Product Name	Product Model	Product Description
Dual-Channel Optical Multiplexer	IDM-NTD421	Provides 2 optical ports, 2 telephone channels, and 2 Ethernet groups;
30E-MP	IDM-30E-MP	Provides 2 optical ports, 30 telephone channels, and 2 Ethernet groups; powered by AC220V