IDM GE Aggregation Bridge

The IDM GE/STM1 Multi-Channel Aggregation Bridge is an intelligent aggregation bridge for high-capacity Ethernet leased line access, developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. It aggregates 63 E1 channels into a gigabit Ethernet port and connects directly to SDH equipment. As a 63-channel E1 aggregation bridge on the central office side, this bridge converter consolidates rows of 2M interfaces and patch cords in the equipment room into a single 19-inch 1U chassis, reducing network construction and maintenance costs.

The device transparently carries Ethernet data with channels as link units; the conversion process is transparent to upper-layer services, and the two ends can intercommunicate once configured according to the same channel plan. For O&M, local configuration is performed through the console port, or the device can be incorporated into unified network-wide management through the SNMP network management interface, with configuration delivery, alarms, and status queries centralized in the central equipment room. In optical transmission equipment networking scenarios, the device can be deployed alongside MSTP and SDH equipment, making it suitable for application environments with high link reliability requirements, such as government private network optical fiber communication solutions and military emergency communications vehicle solutions. As a professional SDH equipment manufacturer, Raytrans provides complete selection support for SDH equipment and bridge converters in its product showcase.

Key Specifications at a Glance: 63-channel E1 aggregation · 2×STM-1 interfaces · 1 optical + 1 electrical gigabit Ethernet · 1+1 protection · dual power supply redundancy · 19-inch 1U chassis

Figure 1: Front view of the IDM GE/STM1 Multi-Channel Aggregation Bridge, showing power and link indicator LEDs

What Kind of Device Is a 63-Channel E1 Aggregation Bridge?

A 63-channel E1 aggregation bridge is a central office aggregation device that consolidates multiple 2M-level E1 channels into a gigabit Ethernet port, functioning like merging scattered E1 leased lines on the equipment room side into one large Ethernet pipe. A single STM-1 interface can map 63 E1 channels, and the device can arbitrarily divide and configure 1 to 63 channels according to service bandwidth, with each channel consisting of one E1 or multiple (4, 8, 16) E1 channels. As a bridge converter for private network scenarios, it is often categorized in the product showcase as an SDH equipment access companion product and is used with direct connection to SDH optical transmission equipment.

Channel division allows the same chassis to simultaneously carry multiple leased lines of different sizes: a site with small bandwidth requirements gets one E1, while a site with concentrated services bundles multiple E1 channels into one channel. Bandwidth is automatically allocated within a channel according to the number of E1 lines, and asymmetric E1 line transmission is supported, so collection-type services with asymmetric uplink and downlink service volumes need not configure channels according to the larger side.

The access scale of a single device depends on how many E1 channels the remote bridge uses: the more remote E1 interfaces, the fewer remote stations a single device can support. The table below lists the number of access points per device by remote device type; during selection, simply convert according to the actual configuration of remote devices in the existing network.

Remote Device Type	Access Points per Device	Description/Applicable Conditions
Single-E1 protocol converter	63	Each remote end occupies 1 E1 channel
4E1 protocol converter	15	Each remote end occupies 4 E1 channels
8E1 protocol converter	7	Each remote end occupies 8 E1 channels
16E1 protocol converter	3	Each remote end occupies 16 E1 channels; margin depends on actual channel planning

A frame sequence transmission delay difference of 64 ms is allowed between any two E1 channels within a channel, which is the basis for stable operation of the device on complex networks. Transmission delays of different E1 paths inherently differ; allowing a certain delay difference means each E1 path need not be strictly equal in length and delay, and E1 circuits across rings and sections in carrier networks can be bundled into the same channel as usual. This feature also enables the bridge converter, in government private network optical fiber communication solutions, to adapt to existing network conditions where E1 circuits across departments and regions have inconsistent delays.

What Functions Does This Aggregation Bridge Provide? Item-by-Item Comparison with Site Requirements

Functions are concentrated in four areas: E1 aggregation, STM-1 transmission, bandwidth allocation, and O&M management, each corresponding to verifiable on-site actions. The table below lists capabilities and effects by function item; during selection, compare row by row against the site's E1 resources, SDH port forms, and O&M approach.

Function	Description
63-group E1 aggregation	A single device aggregates 63 groups of E1 into a gigabit Ethernet port, so the equipment room no longer needs to bring out interfaces and patch cords separately for each 2M service.
STM-1 channel mapping	A single STM-1 interface can map 63 E1 channels; services are transported over distance via the existing SDH network and can interface with both SDH equipment and MSTP platforms.
Arbitrary channel division	Supports arbitrary division and configuration of 1 to 63 channels; each channel can consist of one E1 or multiple (4, 8, 16) E1 channels.
Automatic bandwidth allocation	Bandwidth is automatically allocated within a channel according to the number of E1 lines; the more channels allocated, the greater the bandwidth available to that link.
Asymmetric E1 transmission	Supports asymmetric E1 line transmission; sites with unequal uplink and downlink service volumes configure channels according to actual requirements.
Dual STM-1 interfaces	Provides 2 STM-1 interfaces and can operate in SDH ring and chain networks; the two optical ports can correspond to two transmission directions respectively.
1+1 protection	The two STM-1 interfaces can provide 1+1 protection, so services can be maintained when one optical path fails.
Gigabit Ethernet interfaces	Provides 2 gigabit Ethernet interfaces in total (1 optical + 1 electrical); the optical port is used for long-distance uplink, and the electrical port connects to a local switch or router.
Multi-vendor hybrid networking	Strong compatibility; supports hybrid networking with single/multi-E1 bridges from different vendors as remote devices.
Frame sequence delay difference tolerance	Guarantees a frame sequence transmission delay difference of 64 ms between any two E1 channels within a channel, preventing service misordering on complex networks.
Console local configuration	Provides a console port for on-site channel division, interface parameter, and alarm configuration using a portable computer.
SNMP unified network management	Provides an SNMP network management interface for unified network-wide management, with centralized viewing of status and alarms across multiple devices.
Dual power supply redundancy	Uses a standard 19-inch 1U chassis with dual power supply redundancy design; a single power supply failure does not affect services.

Technical Specifications and Interface Specifications

Parameters are listed in groups by interface, channel, management, and overall unit configuration; nominal values follow the product documentation. As an SDH bridge that connects directly to SDH transmission equipment, interface forms and channel numbering must be aligned item by item with the opposite end; for items not given in the documentation, the confirmation method is noted in the Description column—confirm with the manufacturer before signing the contract rather than estimating based on similar equipment. As an SDH equipment manufacturer, Raytrans provides the following interface and channel specifications in its product showcase documentation for this type of bridge converter, which can be compared item by item with the optical transmission equipment side during selection.

Item	Parameter/Specification	Description/Applicable Conditions
Device model	IDM GE/STM1 Multi-Channel Aggregation Bridge	Central office aggregation-type bridge, directly connected to SDH transmission equipment
Number of STM-1 interfaces	2	Supports SDH ring and chain network networking and 1+1 protection
E1 mappings per interface	63 E1 channels	Upper limit of E1 mappings within a single STM-1 interface
Channel division range	Arbitrary division of 1–63 channels	Each channel consists of 1 or multiple (4, 8, 16) E1 channels
In-channel bandwidth allocation	Automatic by number of E1 lines	Supports asymmetric E1 line transmission
Frame sequence delay difference tolerance	64 ms	Transmission delay difference between any two E1 channels within a channel
Gigabit Ethernet interfaces	1 optical + 1 electrical, 2 total	Optical port for long-distance uplink; electrical port for local network devices
Remote device compatibility	Single/multi-E1 bridges from different vendors	Supports hybrid networking; select remote ends by number of E1 channels
Management interfaces	Console port, SNMP network management interface	Supports unified network-wide management
Chassis	Standard 19-inch 1U	Rack-mounted installation; can be installed in an integrated cabinet at the site
Power supply	Dual power supply redundancy	Two power feeds connected simultaneously; a single feed failure does not affect services
Overall power consumption	Not yet recorded in the knowledge base	Subject to technical documentation supplied with the unit and ordering configuration
Operating environment (temperature, humidity)	Not yet recorded in the knowledge base	Confirm with the manufacturer according to equipment room conditions

Figure 2: Rear panel layout of the bridge, showing STM-1 optical ports, 1 optical + 1 electrical gigabit Ethernet ports, and dual power connectors

Four Capability Labels: 63-Channel E1 Aggregation, 2×STM-1, 1+1 Protection, Dual Power Supply Redundancy

On-site discussions often use four phrases to summarize the device's capabilities, and procurement lists, system diagrams, and acceptance documents can use the same set of terms. The four labels correspond to the four dimensions of capacity, transmission direction, protection, and power supply; the table below explains the boundary conditions and implementation of each.

Differentiation Point	Value on Site
63-channel E1 aggregation	A single device consolidates 63 groups of E1 into a gigabit Ethernet port, saving the equipment room a large number of 2M interfaces and patch cords and reducing rack positions and points of failure.
2×STM-1	The 2 STM-1 interfaces can correspond to the two directions of a ring network respectively and connect directly to SDH transmission equipment without additional intermediate devices.
1+1 protection	Two STM-1 optical paths work simultaneously; services are maintained when one fails, and private network links are carried in protection mode.
Dual power supply redundancy	The 19-inch 1U chassis accepts dual power feeds; the device does not lose power when a single power feed in the equipment room is abnormal, making it suitable for unattended sites.

It should be noted that 1+1 protection acts on the STM-1 transmission side, while dual power supply redundancy acts on the device power supply side; the two mechanisms do not replace each other. During design, verify them separately according to the site's reliability requirements, and state both the protection mode and the power supply configuration clearly in the two lists. In government private network optical fiber communication solutions, this bridge converter is often combined with MSTP and SDH optical transmission equipment to form ring network links; in military emergency communications vehicle solutions, its dual power supply redundancy and 1+1 protection capabilities correspond to on-site constraints of vehicle-mounted power supply fluctuation and link interruption, and can be verified together with the reliability requirements of these two types of scenarios during selection.

How to Deploy: Point-to-Point, Chain Network, and Ring Network

The device can be networked in three ways: point-to-point, chain network, and ring network. The central side handles aggregation, and the site side deploys remote E1 bridges for access; the channel division and E1 numbering at both ends must correspond one-to-one. The three modes differ in the number of STM-1 optical ports used and the protection configuration; the device itself and the configuration method remain the same.

• Point-to-point: One device at each end, interconnected via the STM-1 optical direction; the gigabit Ethernet ports at both ends achieve point-to-point intercommunication, suitable for an independent leased line between two equipment rooms.
• Chain network: Multiple sites are connected in series along one transmission link; the central equipment room device aggregates E1 services sent from sites along the line, suitable for backbones distributed in a belt shape.
• Ring network: The 2 STM-1 interfaces connect to the two directions of the ring respectively; the link has another transmission path, and with 1+1 protection, services are maintained when a single section of optical path is interrupted.
• Hybrid networking: Remote ends can use single-E1, 4E1, 8E1, and 16E1 bridge converters from different vendors; the central side aggregates uniformly by number of E1 channels, so existing equipment in the network need not be replaced in bulk.

Figure 3: Topology diagram of the IDM GE/STM1 Multi-Channel Aggregation Bridge forming a ring network with SDH equipment via STM-1 and aggregating E1 services from various sites

During networking, first determine the E1 circuit routes from the central equipment room to each site, then convert each service into a number of channels and write them into the channel configuration tables at both ends. In chain and ring network modes, plan the receive/transmit optical power and channel numbering of the STM-1 optical ports uniformly, and update both ends synchronously after any change at either end to avoid one-way communication while two-way communication fails.

Typical Application Scenarios

The common point of the following three industries is that a batch of 2M channels is already running in the equipment room, and new Ethernet services need to be accessed without laying new optical cables. The device plays the same role in such scenarios: aggregation on the central side, long-distance transport on the SDH side, and gigabit Ethernet output on the service side, forming a complete product showcase solution.

Electric Power Private Network: One Device at the Dispatch-Side Equipment Room Aggregates 2M Services from Multiple Sites

Between substations, power supply stations, and the dispatch center, a batch of 2M channels usually already carries production services, and newly added electric energy acquisition, records synchronization, and auxiliary control data can be transmitted remotely over these channels directly. A 63-channel E1 aggregation bridge is installed in the dispatch-side equipment room; the E1 services sent from each site are aggregated into gigabit Ethernet (GE) ports and then uplinked to SDH equipment.

The modification work is concentrated on rack positions and patch cords at the equipment room side: the interfaces and cables originally laid out separately for each 2M service are consolidated into one 19-inch 1U device, and cabinet space and wiring workload decrease accordingly. Dual power supply redundancy matches the operating conditions of unattended sites, and the O&M side checks device and channel status through SNMP network management.

Rail Transit: Bandwidth Allocated by E1 Channel at Stations Along the Line

Service volumes differ greatly between stations along the line and section equipment rooms; some sites need only one E1 channel, while others bundle multiple E1 channels into a single channel. The device divides bandwidth by channel at the central side, and different stations are allocated a number of E1 channels according to actual service volume; Ethernet terminals such as cameras and environmental monitoring devices connect to existing transmission channels.

When site services are adjusted, only the channel configuration is changed, without touching cables: when a site is expanded, a channel originally composed of one E1 is changed to 4 E1 channels, and bandwidth increases accordingly. Section equipment rooms have limited space, and the 1U chassis can be installed directly into an existing integrated cabinet; the central network management can locate alarms on a specific channel.

Military and Government Private Networks: Eliminating Rows of 2M Patch Cords in Existing SDH Equipment Rooms

Between equipment rooms of military and government private networks, often only SDH circuits are allocated, and new Ethernet services need to be accessed without changing the existing transmission plan. The device directly interconnects with SDH transmission equipment through 2 STM-1 interfaces, provides 1 optical and 1 electrical gigabit Ethernet (GE) port on the service side, and the modification work is concentrated on one 1U device and two patch cords. This approach also applies to the rapid deployment requirements of government private network optical fiber communication solutions and military emergency communications vehicle solutions.

Remote devices in private networks often come from different sources, and early single-E1 bridges and newly deployed 4E1 and 8E1 devices may be online at the same time. The device supports hybrid networking with single/multi-E1 bridges from different manufacturers as remote devices, and the central side aggregates them uniformly by number of E1 channels, preserving existing investment while centralizing whole-network monitoring into one SNMP network management system.

Conclusion

As a 63-channel E1 aggregation bridge for central office aggregation, the IDM GE/STM1 multi-channel aggregation bridge aggregates 63 groups of E1 into gigabit Ethernet (GE) ports and directly interconnects with SDH transmission equipment through 2 STM-1 interfaces, reducing 2M interfaces and patch cords in the equipment room in batches. The device divides bandwidth by channel and automatically allocates by number of E1 channels; a channel can consist of one E1 channel or be bundled from 4, 8, or 16 E1 channels. As an SDH equipment manufacturer deeply engaged in the optical transmission equipment field, Raytrans has accumulated rich experience in product showcase and solution implementation for MSTP and SDH equipment, and the above aggregation bridge is a representative product for central office aggregation scenarios.

For electric power, rail transit, and military and government private networks, the value of this approach lies in accessing new Ethernet services without changing the existing transmission plan: existing E1 resources continue to be used, E1 bridges from different manufacturers at the remote end continue to be used, and 1+1 protection and dual power supply redundancy place reliability on both the transmission and power supply sides. When calculating the access scale, the configuration can be derived by comparing the number of remote E1 channels against the ratio table.