Alcatel 1660SM Multi Service Node Operations and Troubleshooting

Alcatel 1660SM Multi Service Node Operation and Troubleshooting Manual

In urban and regional transport networks, Alcatel 1660SM, as a new generation SDH multi service node (OMS N), has become one of the best platforms for balancing traditional TDM and emerging packet services, thanks to its full rate support from STM-1 to STM-64, high-order crossover capability equivalent to up to 384 × 384 STM-1, and unique design of the Integrated Service Adapter (ISA) data service plugin. However, the complex mixed business load and increasing bandwidth requirements have put forward higher requirements for operation and maintenance personnel - from correctly configuring cross connections, deploying protection mechanisms reasonably, to quickly locating faults such as optical path degradation and data board abnormalities, a set of systematic operation guidelines is needed. This article is based on the product technology description of 1660SM, and systematically outlines its core functions such as hardware composition, synchronization timing, cross connection, protection switching, and data business integration. Combined with common fault scenarios, it provides positioning and recovery suggestions, providing a practical maintenance reference for transmission network engineers.

Product positioning and hardware architecture

1660SM belongs to the Alcatel OMSN product family and is a multi service node suitable for urban edge, regional backbone, and international gateway. It can flexibly add/drop and cross connect PDH (2/34/45/140 Mbit/s) and SDH (STM-1/4/16/64) signals within the same chassis, while providing Ethernet, ATM, and packet ring switching capabilities through ISA cards, truly achieving the integration of TDM and packet services.

Chassis and Slot: 1660SM adopts a 19 inch standard rack, with dimensions of 482 mm (width) x 650 mm (height) x 250 mm (depth). The chassis is divided into two parts: the upper part is the access area (21 slots), which is used to install various access modules (such as 21 × 2M, 3 × 34/45M, 4 × 140/STM-1 electrical, 12 × STM-1 optical, 14 × 10/100BaseT, etc.); The lower part is the motherboard area, which accommodates control, matrix, clock, and business cards, with a maximum of 16 business cards that can be inserted. When fully configured, a single box can provide 378 2M interfaces, 64 140M/STM-1 interfaces, 16 STM-16 interfaces, or 4 STM-64 interfaces.

Core components:

SDH matrix module (including clock reference): realizes high-order/low order cross connection, with high-order capacity of 384 × 384 STM-1 equivalent (i.e. 384 VC-4) and low order capacity of 256 × 256 STM-1 equivalent (i.e. 16128 VC-12). The matrix supports unidirectional/bidirectional point-to-point, point-to-point, SNCP, and MS-SPRing protection.

Device Controller (EC): Responsible for DCC channel management, network management interface (Q interface and local terminal), and database storage, and can be configured through PCMCIA card backup.

Power subsystem: adopting distributed DC/DC conversion, each board comes with its own converter, with an input of -48V~-60V, naturally possessing single point fault isolation capability.

ISA data board: including ISA Ethernet（10/100BaseT）、ISA Gigabit Ethernet、ISA ATM（600M/1200M）、ISA Packet Ring  Provide L2 switching, MPLS encapsulation, ATM switching, and statistical multiplexing functions.

Cross connection and Business Configuration Fundamentals

The cross connection matrix of 1660SM is the core of the entire system. When configuring circuits, operation and maintenance personnel need to choose appropriate high-order/low order channels based on the type of business:

High level connection: AU-4 level crossover, suitable for 140M/STM-1 and above rate services, can support VC-4 full path or high-order virtual cascading (VC-4-4c/16c/64c).

Low order connection: TU-12 (2M) and TU-3 (34/45M) level crossover, used for low-speed PDH services and partial data mapping.

Example configuration steps (point-to-point 2M circuit):

On the network management or local terminal, select the 2M port at the source end (such as the first 2M of the 63x2M card in slot 1).

Select the destination 2M port (such as the 5th 2M of slot 2 63 × 2M card).

Specify the crossover type (unidirectional or bidirectional), protection mode (SNCP/I or SNCP/N, or unprotected).

After confirming the crossover, the system automatically establishes a connection and can view the error rate of the circuit in performance monitoring.

Advanced features: The matrix supports continuous cascading of AU4-4C/16C/64C, used to carry ATM or Ethernet converged streams. For example, an STM-16 port can be directly connected to an ISA GigE card through a matrix as a VC-4-16c to achieve a high bandwidth data pipeline.

Clock synchronization and timing mechanism

The 1660SM Clock Reference Subsystem (SETS) provides reliable device clocks (SEC) that can be locked to external 2MHz/2Mbit/s references, any STM-n line, or 2Mbit/s service port, and can also oscillate freely. Key configuration points:

Reference source priority: The system automatically selects the optimal clock source based on the SSM (Synchronous Status Message) quality level and user-defined priority table.

Working modes: Locked, Holdover, and Free run. In hold mode, the clock drift does not exceed 0.37 ppm per day, ensuring short-term accuracy even after the reference source is lost.

Output: Provides two external 2MHz/2Mbit/s outputs for synchronizing downstream devices.

Common clock faults:

If a large number of AU pointer adjustment events occur, it often indicates unstable clock source or improper SSM configuration. The current locked source (show sync) should be checked to confirm that the reference source quality is qualified.

Keeping in mode for too long (more than a few days) may result in drift exceeding the standard, and the reference source link should be repaired in a timely manner.

Protection mechanism and high availability

1660SM supports multiple network level and device level protections to ensure business continuity:

MSP (Multiplexing Segment Protection): 1+1 or 1:1 linear protection, can be used for end-to-end or single ended protection at any rate from STM-1 to STM-64.

SNCP (Subnet Connection Protection): Based on channel dual sending and selective receiving, supports one-way and two-way, and can be applied to any VC level (VC-12/3/4). There are two modes: SNCP/I (intrinsic) and SNCP/N (non-invasive), the latter allowing the protection channel to simultaneously carry additional traffic.

MS-SPRing (Shared Protection Ring for Reuse Segment): Supports 2 or 4 fiber STM-64/STM-16 rings, can protect up to 96 STM-1 equivalent services, and has a switching time of less than 50ms.

Equipment redundancy: Matrix modules (including clock) and device controllers can both be 1+1 hot standby; The distributed power design does not require additional backup modules.

Protection configuration suggestion:

For important aggregation nodes, priority should be given to configuring matrix 1+1 redundancy and enabling automatic switching in network management.

SNCP can flexibly set the recovery mode (non recovery/recovery), and the recovery time can be adjusted (usually set to 5-12 minutes).

Regularly perform protection switching tests (manual forced switching) to verify whether the switching logic and signaling (K1/K2 bytes) are normal.

Data Business Integration and ISA Card Application

ISA (Integrated Service Adapter) is the key difference between 1660SM and traditional SDH equipment. It enables TDM and packet services to be carried simultaneously on the same platform, reducing device stacking and operational complexity.

ISA Ethernet card:

Provide 10/100BaseT or GigE interfaces, supporting GFP encapsulation, VC virtual cascading (N combinations of VC-12/3/4), and LCAS (link capacity adjustment), which can dynamically adjust bandwidth without interrupting business.

The rate adaptation function enables Ethernet streams to be mapped to containers of any size, achieving fine-grained bandwidth customization (such as 5 Mb/s to 200 Mb/s steps).

ISA ATM card:

600Mbps (single slot) and 1.2Gbps (dual slot) two capacities, supporting VP/VC switching, including hard PVC and PNNI soft PVC.

Support traffic types: UBR, UBR+, CBR, VBR-rt/nrt, GFR, and provide EPD/TPD congestion dropout mechanism.

Suitable for DSLAM aggregation, 3G base station backhaul (IMA function) and other scenarios.

ISA Packet Ring:

6.4 Gbps switching capacity, based on MPLS technology, providing E-Line, E-LAN, and broadcast access services.

Support classification and QoS (guarantee, control, best effort) based on ports, VLANs, MAC, MPLS labels, etc.

Key points of operation and maintenance:

When installing ISA cards, pay attention to the slot type - Enhanced slots provide higher backplane bandwidth (such as GigE cards that can reach 1.2 Gb/s in enhanced slots).

When configuring LCAS, it is necessary to ensure that both devices support the protocol and that all member channels in the virtual cascaded group (VCG) are in normal condition.

If packet loss occurs in Ethernet services, check the FCS error count and LCAS status of GFP frames, as well as the error performance of SDH channels.

Alarm and Performance Monitoring (PM)

1660SM supports rich SDH overhead processing and can report all alarms and performance data to the network management (such as Alcatel 1350 NM) through DCC channel. Daily maintenance should focus on:

Key alarm:

LOS (signal loss), LOF (frame loss), MS-AIS, AU-LOP, etc. - physical layer or multiplexing segment issues.

B1/B2/B3 bit errors - corresponding to the bit errors of the regeneration section, multiplexing section, and high-order channel, respectively, need to be combined with a 15min/24h performance threshold to determine the trend.

Low level channel alarms (such as TU-LOP, TU-AIS, V5 bit errors) - related to 2M/34M services.

Performance monitoring parameters:

ES, SES, BBE, UAS, etc. are counted according to the ITU-T G.826 standard.

TCA (threshold crossing alarm) can be set, for example, triggering an alarm when ES>10/15 minutes to warn in advance of line degradation.

Positioning steps:

If there are a large number of B2 errors, first check the optical transmission and reception power to ensure that the received optical power is within the sensitivity range.

If the error code only appears in a specific VC channel, check if the cross connection of that channel is stable, there may be a matrix hardware failure.

For persistent errors, use OTDR to test fiber loss or replace the optical module for testing.

Common fault scenarios and systematic troubleshooting

7.1 Optical Port LOS or LOF

Check if the fiber optic connector is loose or contaminated; Clean or replace the jumping fiber.

Measure the received optical power with an optical power meter, and if it is lower than the sensitivity (such as -28 dBm), check the transmitting power and line attenuation at the other end.

If the optical power is normal but still alarms, check whether the other end device is sending signals normally or whether the local optical module is faulty.

7.2 Protection switching not triggered or switching failure

Check the status of the protection group ("idle" or "activated") and confirm that there are no alarms on the protection port.

Check if the protocol bytes (K1/K2) are exchanged correctly, and capture the overhead on the crossbar.

If it is SNCP, verify whether the cross connection of the protection path is correctly established and whether the signal labels (C2) at both ends are consistent.

7.3 Data service failure (ISA card)

Confirm the port status of the ISA card (LINK UP/DOWN) and check the network cable or fiber optic connection.

Check the error rate of the SDH mapping channel. If there are errors in the channel, it may affect data encapsulation.

Check the frame synchronization and LCAS status of GFP. If VCG members fail, bandwidth will decrease, which may lead to traffic congestion.

7.4 Network management is unable to manage devices

Check if the DCC channel is enabled and ensure that the D1-D12 bytes of RSOH or MSOH have been correctly allocated.

If using the Ethernet management port (such as the Ethernet port on the EC board), check the IP address and routing.

Confirm that the PCMCIA card of the device controller is correctly inserted and that the database is not damaged.

Software Upgrade and Backup Strategy

1660SM supports local and remote software downloads, and the following preparations need to be made before upgrading:

Backup the current database (exported via PCMCIA card or FTP).

Check the compatibility between the new version of software and existing hardware (especially ISA cards).

For dual matrix configuration, upgrade the backup matrix first, switch and then upgrade the primary matrix to ensure uninterrupted business.

After upgrading, verify all cross connections and protection functions, and observe performance indicators for at least 24 hours.