IDM GP2000-4E1 PDH Optical Multiplexer

The IDM GP2000-4E1 PDH optical multiplexer is a 5-channel E1 dual-optical-port PDH optical multiplexer developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. It is used to simultaneously transmit 5 groups of E1 circuits and 2 channels of 1000M Ethernet service over the same 2.5Gbps optical fiber link. As a typical multi-service optical multiplexer, the device provides an SNMP network management interface and alarm monitoring functions, with high integration, low power consumption and stable performance. It is suitable for nodes of private networks such as public security, electric power, railway and mining, as well as carrier public networks, and is also one of the representative models of the optical multiplexer manufacturer Raytrans on its PDH product line.

Figure 1: Front view of the IDM GP2000-4E1 PDH optical multiplexer, showing the rack-mounted enclosure and front-panel alarm indicator LEDs

The access requirements of private network sites usually concentrate on three points: many types of narrowband service but limited capacity at a single point, tight cabinet rack space, and limited available optical fiber resources. The IDM GP2000-4E1 packs 5 E1 channels, 2 gigabit Ethernet ports and redundant optical ports into one rack-mounted device, so the site side needs only one rack position and one optical fiber link, and cabinet footprint, supporting power supplies and cabling are reduced accordingly. This product showcase approach also applies to scenarios such as government private network optical fiber communication solutions, smart mining communication solutions and military emergency communications vehicle solutions, where a single gigabit network optical multiplexer can handle both narrowband service and broadband data access.

Key specifications at a glance: 2 groups of 2.5G SFP optical ports (standard 20Km) · 5 groups of E1 (ITU-T G.703, 75Ω/120Ω) · 2 channels of 1000M line-rate Ethernet · dual SFP mutual backup · receiver sensitivity better than -24dBm · AC220V/DC-48V dual power supply · overall power consumption ≤90W

What is a 5-channel E1 dual-optical-port PDH optical multiplexer

A 5-channel E1 dual-optical-port PDH optical multiplexer is a device that multiplexes narrowband E1 circuits and broadband Ethernet onto the same 2.5Gbps optical fiber for transmission. One unit is deployed at each end of the link: one end combines the various services and feeds them into the optical fiber, and the other end restores them to standard interfaces for output. All services on the service side are interfaced according to common standards, so no change to the original configuration is required when connecting to existing switching equipment, routers or monitoring platforms, and the site modification workload is small. It is a typical model in the PDH product showcase for private network access scenarios.

Figure 2: Rear panel of the IDM GP2000-4E1 PDH optical multiplexer, showing the layout of E1 interfaces, gigabit Ethernet ports and dual SFP optical ports

How E1 and Ethernet services run in parallel over the same pair of optical fibers

E1 channels are organized according to the PCM30/32 frame structure, with a bit rate of 2.048Mbps and HDB3 line code, compliant with the ITU-T G.703 standard, with selectable 75Ω or 120Ω impedance. The 5 groups of E1 are transmitted in transparent transmission mode without changing the time slot content, and can be enabled by connecting to the E1 ports of existing PCM equipment or switches, with signaling transmitted together with the service in channel-associated mode.

Ethernet channels are encapsulated according to IEEE802.3. The 2 gigabit interfaces forward at 1000M line rate and are backward compatible with 10M/100M, with adaptive full/half duplex. E1 and Ethernet use independent channels inside the device and are multiplexed within the 2.5G optical port according to fixed bandwidth allocation, so the two types of service do not preempt each other's capacity. This design, which concentrates multi-service optical multiplexer capabilities in a single PDH optical multiplexer, enables one device to carry both leased-line channels and data backhaul at the same time.

How dual SFP mutual backup protects the optical link

The two groups of SFP optical ports back each other up. When the primary optical link is interrupted, services are switched to the standby optical port and continue to be transmitted, so a single optical cable failure will not cause the entire site to lose contact. The optical ports have a receive/transmit rate of 2.5G and use 1310nm/1550nm wavelength modules in pairs, with a standard transmission distance of 20Km; long-distance optical modules can be optionally installed to extend the link farther. For link protection between long-distance sites in government private network optical fiber communication solutions, this mechanism can directly reuse existing optical fiber resources.

Core functions and interface configuration

The functions of the IDM GP2000-4E1 PDH optical multiplexer are designed around three main lines: E1 transparent transmission, Ethernet line-rate forwarding and optical link protection. The interface form and on-site role corresponding to each function item are summarized in the table below. By checking row by row according to service type, the cabling method can be determined, and it is also convenient to align item by item with existing equipment in the equipment room.

Function	Description
Dual SFP mutual backup	2 groups of SFP optical ports back each other up; when the primary optical link is interrupted, services are switched to the standby optical port, so a single optical cable failure does not interrupt site services
5 E1 circuits	Provides 5 groups of E1 interfaces, bit rate 2.048Mbps, HDB3 line code, compliant with ITU-T G.703, with selectable 75Ω/120Ω impedance
2 gigabit Ethernet ports	2 channels of 1000M line-rate Ethernet interfaces, compliant with IEEE802.3, adaptive 10M/100M/1000M and adaptive full/half duplex
2.5G optical port	Receive/transmit rate 2.5G, single-mode fiber with optional multi-mode, wavelength 1310nm/1550nm, standard transmission 20Km
SNMP network management interface	Provides an SNMP network management interface, supporting centralized configuration, status viewing and alarm reporting, with hierarchical monitoring from the duty room
Alarm monitoring function	Two levels of indication: panel indicator LEDs and network management alarms; no light at the optical port, E1 channel loss and power supply abnormality can all be located
Dual power supply access	AC220V and DC-48V formats selectable, connected according to the AC mains power or DC distribution panel conditions in the equipment room
Interworking with GP2400	Can interwork via optical ports with IDM GP2400 series optical multiplexers; devices of the same family form a point-to-point link, with both ends configured at the same rate

Technical specifications and interface specifications

The following parameters cover optical interfaces, E1 interfaces, Ethernet interfaces, power supply and environmental conditions. The values are taken from the IDM GP2000-4E1 product documentation and are provided for checking during networking design and equipment selection. If on-site conditions or ordered configurations differ from the table below, the optical multiplexer manufacturer's technical documentation and commercial confirmation shall prevail.

Item	Parameter/Specification	Description/Applicable Conditions
Optical interface type	SFP	Pluggable optical module, selected according to distance and fiber core conditions
Fiber mode	Single-mode (multi-mode optional)	Multi-mode is used for short-distance interconnection within the equipment room
Receive/transmit rate	2.5G	The 2 groups of SFP optical ports operate at this rate
Receive/transmit wavelength	1310nm/1550nm	Two wavelengths selectable, used in pairs at both ends of the link
Transmit optical power	-1~-3dBm	Typical value for single-mode modules; subject to actual measurement with an optical power meter
Receiver sensitivity	Better than -24dBm	The link loss budget can be calculated on this basis
Transmission distance	20Km	Standard configuration; long-distance optical modules can be optionally installed to extend farther
Number of E1 interfaces	5 groups	Subject to the ordered model and factory configuration
E1 bit rate and line code	2.048Mbps / HDB3	Compliant with ITU-T G.703
E1 interface form	75Ω-BNC / 120Ω-RJ45	Impedance matching with the peer device, consistent at both ends
E1 frame structure and signaling	PCM30/32 / channel-associated signaling	Time slot content is not changed during transparent transmission
Ethernet interfaces	2 channels of 1000M line rate	Adaptive 10M/100M/1000M, compliant with IEEE802.3
Ethernet operating mode	Full/half duplex/adaptive	Auto-negotiation with the peer device
Power supply mode	AC220V/DC-48V	The two power supply formats are selected according to on-site conditions
Overall power consumption	≤90W	Unit value including optical modules
Operating temperature	-10℃~+50℃	Suitable for unattended equipment rooms and field sites
Relative humidity	0~95% (non-condensing)	No condensation should form inside the cabinet
Dimensions	482×309×132mm	19-inch rack-mounted structure, including mounting ears

Differentiated capabilities and private network value

The three differentiated capabilities of the IDM GP2000-4E1 fall in three directions: interface density, optical link budget and power supply adaptability, corresponding to the on-site conditions of private network sites such as tight rack space, long distances and varied power supply conditions. The table below lists them item by item according to the correspondence between capability and value, making it convenient to check the configuration according to site conditions.

Differentiated capability	Value to private network sites
Dual SFP optical ports with mutual backup; a single unit integrates 5 E1 channels and 2 gigabit Ethernet ports	More space-saving private network access: one device handles leased-line channels and data backhaul, reducing cabinet footprint, power supply modules and cabling at the same time, with an extra layer of backup on the optical link
2.5G optical port rate, 20Km transmission distance, receiver sensitivity better than -24dBm	More stable and longer links: the link loss budget is comfortable, optical fiber resources between long-distance sites can be used directly, and long-distance optical modules can be installed when the standard distance is exceeded
AC220V/DC-48V dual power supply, overall power consumption ≤90W	Adapts to private network equipment rooms and field power supply environments: both AC mains power and DC distribution panels can be connected, and low power consumption reduces cabinet heat dissipation pressure and uninterruptible power supply burden

This interface division allows one 2.5G optical multiplexer to handle both leased-line channels and data backhaul, so the site side no longer needs to connect an external switch or provide a separate multiplexing device. As a combination of a gigabit network optical multiplexer and a multi-service optical multiplexer, this model also has deployment value in scenarios such as smart mining communication solutions and military emergency communications vehicle solutions. The objects of service cutover and routine maintenance are also concentrated on one device, so troubleshooting no longer requires repeatedly switching cables among multiple small devices to make a judgment. Raytrans's continuous supply and technical support for this product series also provide a guarantee for the long-term operation and maintenance of private network projects.

Typical application scenarios

The site access requirements of private networks such as public security, electric power and railway are similar: many types of service, small capacity at a single point, and equipment rooms that are mostly unattended. The following describes the deployment position and service allocation according to the actual networking approach of the three industries. On site, the configuration can be adjusted according to the number of E1 channels and Ethernet ports at the site, and it is also convenient for the optical multiplexer manufacturer to check during selection.

Public security private network: leased-line channels and surveillance backhaul from police station to sub-bureau

Between the police station and the sub-bureau, it is necessary both to transmit the E1 leased-line channels of the public security intranet and to backhaul the video surveillance and office data within the station. One IDM GP2000-4E1 is deployed at each end, using the E1 ports to carry leased-line services and the 2 gigabit ports to carry surveillance and office data, completing backhaul over one optical fiber, so that increased surveillance traffic will not squeeze the leased-line channels. Such government private network optical fiber communication solutions have high requirements for channel isolation and bandwidth allocation, and the ports can be described by service type in the product showcase.

Electric power private network: substation dispatching channels and in-station data backhaul over the same fiber

Between the substation and the dispatch center, E1 channels such as telecontrol and protection signals and in-station Ethernet data are transmitted in parallel, and the communications cabinet has limited rack space. The IDM GP2000-4E1 combines 5 E1 channels and 2 gigabit Ethernet ports onto one optical fiber, occupying only one rack position in the station; the two power supply formats, AC220V and DC-48V, can be connected according to the in-station DC distribution panel or AC mains power conditions.

Railway private network: channel access between stations and trackside sites

Trackside sites along the railway are scattered and equipment room conditions vary greatly, and trackside sites are often unattended. The IDM GP2000-4E1 adapts to such environments with an operating temperature of -10℃~+50℃ and a standard transmission distance of 20Km. The E1 ports carry signal and service channels, and the 2 gigabit ports connect video and service data respectively, so the site side no longer stacks multiple small devices.

Figure 3: Networking topology of IDM GP2000-4E1 dual SFP optical port mutual backup between public security, electric power and railway sites

How to plan the optical link when interworking with the GP2400 series

The GP2000 device can interoperate over the optical ports with IDM GP2400 series optical multiplexers; the devices at both ends each aggregate the E1 and Ethernet services of their own sites to form a point-to-point link. During planning, first confirm the rate and wavelength of the optical port at the opposite end, then select the SFP module according to the station spacing, and finally calculate the link loss. Once these three steps are complete, place the order, which avoids mismatched modules at the two ends. In multi-service optical multiplexer projects, Raytrans's practice is to first list the model and optical port parameters of the opposite end clearly, and then move on to the product showcase and configuration verification stage.

• Rate and wavelength pairing: both ends use 2.5G optical ports, with 1310nm at one end and 1550nm at the other, and receive/transmit cross-connected
• Distance calculation: standard transmission is 20Km; when the station spacing exceeds this, use long-distance optical modules and recalculate the budget based on a transmit optical power of -1~-3dBm and receiver sensitivity better than -24dBm
• Backup wiring: the two SFP groups are routed over different optical cable routes; mutual backup is only meaningful this way, whereas backup over the same trench and cable has limited value
• Service allocation: E1 ports are used for dedicated line channels, and the 2 gigabit ports separately carry surveillance and office data, with wiring separated by service type
• Network management planning: assign a management IP to each end and incorporate both into the same SNMP network management, so alarms can be viewed centrally

Installation and Commissioning Highlights

The device uses a 19-inch rack-mounted structure with unit dimensions of 482×309×132mm. Installation and commissioning proceed more smoothly in the following order. Each step corresponds to an item that can be checked on site; confirm each item before connecting services to reduce rework and secondary downtime.

• Cabinet positioning: confirm the rack position space, air intake and exhaust, and protective grounding, and check the installation depth against 482×309×132mm
• Optical fiber connection: pair according to the SFP module wavelength, use 1310nm and 1550nm in pairs, and connect receive/transmit crosswise
• E1 wiring: select 75Ω or 120Ω impedance according to the interconnected equipment, and keep the impedance consistent at both ends of the same E1 link
• Ethernet access: connect the 2 gigabit ports by service, and do not mix surveillance and office data on the same port
• Power connection: connect AC220V or DC-48V according to equipment room conditions, and verify the voltage level before powering on both power feeds simultaneously
• Network management configuration: after assigning IP addresses, connect to SNMP network management and confirm that alarm reporting is consistent with the panel indicator LEDs