In urban transmission networks and regional backbone networks, the Alcatel 1600 series SDH multi service platform (including 1650 SMC, 1651 SM, 1660 SM, 1664 SM, and 1686 WM wavelength division multiplexing systems) has become the core transmission infrastructure for many operators and enterprise private networks worldwide due to its high reliability, flexible multi service access capabilities, and complete speed coverage from 2M to 10G. However, the long-term stable operation of SDH networks relies on fine initial planning, rigorous protection configuration, and fast and accurate fault location capabilities. This article is based on the technical features of Alcatel 1600 series products, systematically sorting out the troubleshooting process from device selection, network topology design, protection mechanism configuration to common alarm and performance degradation scenarios in daily operation and maintenance, providing a practical manual that can be directly implemented for transmission network engineers.
Product Family Overview and Selection Decision
The Alcatel 1600 series covers a variety of synchronous digital hierarchy (SDH) devices from low to high order, as well as wavelength division multiplexing (WDM) systems, to meet different rates and business scenarios:
1650 SMC (STM-1/4 Optical Multi Service Node): Supports a full range of PDH/SDH interfaces from 2 Mbps to 622 Mbps, with built-in ISA (Integrated Service Adapter) module, capable of ATM or packet ring switching, as well as Ethernet/Gigabit Ethernet rate adaptive transmission. Suitable for small capacity aggregation nodes in local and metropolitan area networks.
1651 SM (STM-4 synchronous add/drop multiplexer): with a capacity of 622 Mbit/s, it supports adding/dropping multiple branch signals (PDH/SDH, electrical/optical) from STM-4 bidirectional streams in two directions (east/west). Can be configured as a terminal device, line regenerator, or add/drop multiplexer, supporting line protection and unprotected modes. Suitable for medium capacity ring or chain network nodes.
1664 SM (STM-16 synchronous add/drop multiplexer): With a capacity of 2.5 Gbit/s, it supports the add/drop of STM-1 and STM-4 signals. It can accommodate up to 8+1 140 Mbit/s or STM-1 branch units, or 4 STM-4 branch units, and can be configured in a mixed manner. Supports protected/unprotected transmission on standard optical fibers and dispersion shifted optical fibers. Suitable for regional aggregation and high-order access.
1660 SM (STM-64 Multi Service Node): A 10G capacity Multi Service Provider Platform (MSPP) that integrates SDH cross connection and CWDM add/drop functions on a single rack. It also supports Layer 2 packet/cell switching (Ethernet, MPLS, Elastic Packet Ring RPR, ATM). Suitable for backbone layers or large metropolitan core nodes.
1686 WM (wavelength division multiplexer): up to 32 waves of bidirectional transmission, supports G.692 standard optical interface, and can be configured as terminal station and line station (optical amplifier repeater or OADM). Suitable for high-capacity wavelength division transmission links.
Selection suggestion: For sites with small initial capacity requirements and mainly TDM services, 1651 SM or 1664 SM can be selected. If both need to carry packet data and evolve towards PTN in the future, 1650 SMC or 1660 SM should be preferred to obtain built-in packet switching capability. The backbone wave segmentation requires the selection of 1686 WM based on the fiber core resources and the number of channels.
Key points for hardware installation and basic configuration
2.1 Rack Installation and Grounding
All Alcatel 1600 devices are installed in a 19 inch standard rack, with varying heights depending on the model (1660 SM for single rack, 1650 SMC for compact). Ensure sufficient heat dissipation space (≥ 80 cm) is left before and after installation.
The equipment protection grounding must be firmly connected to the machine room grounding bar, with a grounding resistance of ≤ 1 Ω, to prevent lightning and static damage.
2.2 Optical Interface and Fiber Optic Connection
Select the appropriate optical module (SFP/SFP+or fixed optical port) based on the transmission distance, and record the optical power budget. For STM-64 (10G) links, dispersion compensation must be considered and DCM modules must be configured if necessary.
When connecting optical fibers, pay attention to the correspondence between transmission and reception to avoid misconnection. Use OTDR to test the fiber link loss and ensure that the actual loss is within the budget range.
2.3 Clock synchronization configuration
All SDH equipment must be synchronized to an external clock source (such as BIT or GPS). Set the clock source priority through the network management or CLI (e.g. prioritize BITS, secondary select line extraction, and finally internal oscillator).
Enable SSM (Synchronous Status Message) function to enable the device to automatically track the highest quality clock source and smoothly switch when the source fails.