Cisco GSR6-CSC
Cisco 12406 Clock Scheduler Card
Product Highlights
Maintaining a carrier-grade routing platform demands reliable switch fabric components — and the Clock Scheduler Card is the heartbeat of the Cisco 12406 chassis. The Cisco GSR6-CSC is the original 10-Gbps Clock and Scheduler Card (CSC) designed for the Cisco 12406 Internet Router, part of the Cisco 12000 Series Gigabit Switch Router (GSR) platform.
The GSR6-CSC provides a 10-Gbps full-duplex connection to each line card in the system, handling critical clock distribution and cell scheduling functions within the switch fabric. It installs into one of two dedicated half-width CSC slots (CSC 0 or CSC 1) located in the lower-left section of the 12406 chassis. Deploying a second GSR6-CSC in the redundant slot enables automatic failover for data path, scheduler, and reference clock functions — ensuring uninterrupted packet forwarding if the primary CSC encounters a fault.
The GSR6-CSC works in conjunction with the GSR6-SFC Switch Fabric Cards (three SFC slots) to form the complete 10-Gbps switch fabric. Note that this is the original fabric version; it cannot be mixed with enhanced fabric cards (12406E-CSC / 12406E-SFC) in the same chassis. This product is End-of-Life (EOL) and is available as a replacement spare for existing Cisco 12406 deployments.
Features & Benefits
10-Gbps Switch Fabric Performance
The GSR6-CSC provides a 10-Gbps full-duplex connection to each line card installed in the Cisco 12406 chassis. This high-speed fabric interconnect ensures that line cards can forward traffic at wire speed, supporting demanding service provider and enterprise core workloads.
Clock Distribution & Cell Scheduling
As the Clock and Scheduler Card, the GSR6-CSC is responsible for distributing the reference clock signal and managing cell-level scheduling across the switch fabric. These functions are essential for synchronized, deterministic packet forwarding within the router.
High-Availability Redundancy
The Cisco 12406 chassis provides two dedicated CSC slots. Equipping both slots with GSR6-CSC cards delivers data path, scheduler, and reference clock redundancy. If a loss of synchronization is detected, the router automatically activates the redundant CSC's data paths, maintaining uninterrupted operation.
Hot-Swappable (OIR) Design
The GSR6-CSC supports online insertion and removal (OIR), allowing network operators to replace a failed or degraded card without powering down the chassis. This minimizes maintenance windows and supports carrier-grade uptime requirements.
Deployment Scenarios
Replacement Spare for Cisco 12406 Deployments
For organizations still operating Cisco 12406 routers in production, the GSR6-CSC serves as a critical replacement spare. Keeping a spare CSC on hand ensures rapid recovery from hardware failures without waiting for extended lead times on EOL components.
Enabling CSC Redundancy
If your Cisco 12406 is currently running with a single CSC, adding a second GSR6-CSC to the vacant CSC slot provides automatic failover for clock, scheduler, and data path functions — a best practice for any production deployment carrying critical traffic.
Lab and Test Environments
Network engineers maintaining lab environments with Cisco 12406 routers for testing, certification study, or legacy application validation can use the GSR6-CSC to keep these platforms fully operational at a fraction of the original cost.
General
Performance
Compatibility
Features
Compatibility Notes
Chassis Compatibility
- Cisco 12406 Internet Router
- Cisco XR 12406 Router
Fabric Pairing
- Works with GSR6-SFC (12406 Switch Fabric Card) — three SFCs required for full fabric operation.
- Do NOT mix with enhanced fabric cards (12406E-CSC / 12406E-SFC). The chassis will not operate with a mix of original and enhanced switch fabric card types.
Slot Information
- Installs in dedicated half-width CSC slots: CSC 0 and CSC 1 (lower-left chassis area).
- When operating with a single CSC, the empty slot must have a CSC blank filler (MAS-GSR6-CSCBLNK=) installed for proper airflow.
Downloads & Resources
Frequently Asked Questions
| Part Number | Product | Key Difference |
|---|---|---|
| 12406E-CSC | Cisco 12406 Enhanced Clock Scheduler Card | Enhanced fabric version of the CSC for the 12406 chassis — cannot be mixed with original GSR6-CSC fabric cards. |
| GSR6-SFC | Cisco 12406 Switch Fabric Card | Companion switch fabric card that works alongside the GSR6-CSC; three SFCs required per chassis for full fabric operation. |
| 12406E-SFC | Cisco 12406 Enhanced Switch Fabric Card | Enhanced version of the SFC — pairs with the 12406E-CSC (not compatible with original GSR6-CSC fabric). |