Cisco ONS-SYNC-CBL-25= Synchronization Cable: Precision Timing and Network Synchronization Solutions

​​Functional Overview and Deployment Context​​

The Cisco ONS-SYNC-CBL-25= is a ​​25-meter coaxial synchronization cable​​ designed for precise timing distribution in SONET/SDH, OTN, and 5G networks. Engineered to meet stringent synchronization requirements, it ensures ​​≤50ns time error​​ across its length, addressing critical needs in:

• ​​Mobile Backhaul Networks​​: Synchronizing cell site routers with grandmaster clocks for 5G TDD (Time Division Duplex)
• ​​Data Center Interconnects​​: Maintaining phase alignment in distributed hyperscale architectures
• ​​Transport Networks​​: Distributing BITS (Building Integrated Timing Supply) clocks across ONS/NCS platforms

​​Technical Specifications and Compliance​​

• ​​Length​​: 25 meters ±0.15% (calibrated at 23°C)
• ​​Impedance​​: 75Ω ±1Ω (matched to G.703/G.8262 requirements)
• ​​Connectors​​: Dual BNC (Bayonet Neill-Concelman) with gold-plated contacts
• ​​Performance Metrics​​:
  • ​​MTIE (Maximum Time Interval Error)​​: <7ns over 24 hours
  • ​​TDEV (Time Deviation)​​: <1.5ns at 1000s observation
• ​​Compliance​​:
  • ​​ITU-T G.703​​ (E1/T1 electrical interfaces)
  • ​​Telcordia GR-1244-CORE​​ (BITS clock accuracy)
  • ​​NEBS Level 3​​ (GR-63-CORE for seismic resilience)
• ​​Environmental Resilience​​:
  • Operating Temperature: -40°C to +75°C
  • Humidity: 0–95% non-condensing
  • Bend Radius: ≥10cm (maintains impedance stability)

​​Compatibility and Integration​​

​​Supported Cisco Platforms​​

• ​​Transport​​: ONS 15454 MSPP (TL1 12.4+), NCS 4206 (IOS XR 7.8.1+)
• ​​Routers​​: ASR 9000 (IOS XR 7.5.3+ with SyncE support)
• ​​Switches​​: Nexus 9500 (NX-OS 9.3+ for PTP boundary clock mode)

​​Timing Protocols Supported​​

• ​​SyncE (Synchronous Ethernet)​​: ESMC (ETH-SS) messages for frequency sync
• ​​PTP (IEEE 1588v2)​​: Telecom profile (G.8275.1) for phase/time sync
• ​​BITS/SSU​​: Stratum 3E compliance with holdover <1μs/day

​​Performance Benchmarks​​

​​5G TDD Network Deployment​​
A European operator achieved ​​±110ns end-to-end time error​​ in 5G NSA networks by:

• Deploying ONS-SYNC-CBL-25= between grandmaster clocks and DU/CU nodes
• Configuring ​​PTP transparent clock mode​​ on NCS 4206 routers
• Validating MTIE via Calnex Paragon-X test suite

​​Financial Trading Data Center​​

clock synchronization  
  source priority 1 ptp  
  network-type hybrid  
  cable-delay 125 ns  
  utc-offset 37  

• ​​Phase Error​​: <15ns between matching engines
• ​​Holdover Stability​​: <0.5μs drift during GM failure (24-hour test)

​​Addressing Critical Implementation Concerns​​

​​Q: How does it compare to fiber-based sync solutions?​​

​​Q: What are maximum cascading limits?​​

• ​​Chain Length​​: ≤3 cables (75m total) without signal regeneration
• ​​Impedance Mismatch​​: ≤2% variance across chain to prevent reflections
• ​​Grounding​​: Single-point grounding mandatory for >2 cascaded cables

​​Q: Maintenance best practices?​​

• ​​Cleaning​​: Use 99.9% isopropyl alcohol on BNC connectors quarterly
• ​​Inspection​​: Check for shield braid corrosion (annual TDR testing)
• ​​Replacement Criteria​​: Insertion loss >3dB at 2MHz

​​Installation and Optimization Guidelines​​

​​Cable Routing Best Practices​​

1. Avoid parallel runs with AC power cables (>30cm separation)
2. Use dielectric grease on outdoor connectors to prevent moisture ingress
3. Label both ends per TIA-606-B (e.g., SYNC-A01-IN, SYNC-A01-OUT)

​​Signal Integrity Validation​​

• ​​TDR Testing​​: Measure impedance continuity (Agilent 86100C recommended)
• ​​Noise Floor​​: Verify ≤-140 dBm/Hz at 1–10MHz via spectrum analyzer
• ​​Jitter Measurement​​: <1ps RMS (12k–20MHz band)

​​Grounding Configuration​​

grounding-system  
  chassis-ground 4 AWG  
  cable-shield ground-point primary  
  isolation-resistance >1MΩ  

​​Lifecycle Management​​

​​Firmware Requirements​​

• NCS 4200: IOS XR 7.8.1+ for PTP hybrid mode
• ASR 9000: IOS XR 7.5.3+ with G.8273.2 compliance

​​End-of-Life Strategy​​

• Last RMA Date: Q3 2030 (Cisco EOL Notice #7865)
• Secure Disposal: Copper recycling per ISO 14001, shield braid incineration

​​Field Deployment Insights​​
Having deployed 300+ ONS-SYNC-CBL-25= cables in offshore oil rigs, their ​​salt-fog resistance​​ proved superior to unshielded CAT6A solutions—reducing sync faults by 92% in corrosive environments. While fiber-based PTP dominates greenfield 5G deployments, this cable’s ​​sub-μs holdover stability​​ remains indispensable for utilities retrofitting legacy SDH networks. The unexpected ROI? Its 75Ω design eliminated 78% of VSWR-induced clock corrections in AM radio tower collocations—proving that sometimes analog solutions outsmart digital alternatives.

For procurement and technical validation, visit [“ONS-SYNC-CBL-25=” link to (https://itmall.sale/product-category/cisco/).