A900-RSP2A-64= Cisco Route Switch Processor 2 Control Processor Plug-in Module

Product Snapshot of A900-RSP2A-64= Cisco Route Switch

The Cisco A900-RSP2A-64= is a high-performance route switch processor engineered for the Cisco ASR 900 Series. Designed as a control-plane module (control processor) for edge routing platforms, this card delivers up to 64 Gbps of interface throughput and robust management interfaces for carrier-grade applications.

Core Specifications

General details

• Brand: Cisco
• Part number: A900-RSP2A-64=
• Device category: Control processor / route switch processor
• Target platform: Cisco ASR 900 Series

Performance and memory

• Maximum throughput: 64 Gbps
• DRAM (system memory): 4 GB
• Flash storage: 2 GB
• MAC address table: Up to 16,000 entries

Connectivity and management

• Network port: 1 × 1 Gigabit Ethernet RJ-45
• Console / auxiliary: 1 × Console/Aux RS-232 (RJ-45)
• USB: 1 × USB 2.0 Type-A for local file transfer and diagnostics

Compatibility & Supported Modules

This RSP module is compatible with a range of ASR900 line cards and interface modules, enabling easy integration into existing deployments.

Compatible interface modules (examples)

• A900-IMA1X
• A900-IMA2Z
• A900-IMA8S
• A900-IMA8S1Z
• A900-IMA8T
• A900-IMA8T1Z

Use Cases & Deployment Scenarios

Ideal for service provider edge

Deploy this route switch processor in metro and edge routing nodes that require stable control-plane capacity, consistent forwarding rates, and scalable MAC learning for bridging or routed services.

Enterprise WAN aggregation

Suitable for large campus or enterprise WAN aggregation where predictable throughput and administrative access (console + USB) simplify on-site troubleshooting and software updates.

Key Benefits at a Glance

Performance

• 64 Gbps interface processing for latency-sensitive workloads
• Memory and flash sized for typical routing and control-plane functions

Manageability

• Dedicated console port and USB for quick access and backups
• Easy swap-in replacement when servicing ASR 900 chassis

Scalability

• 16,000 MAC entries support large Layer-2 tables and bridging needs
• Compatibility with many A900 IMA modules enables modular growth

Understanding the Cisco ASR 900 Series Route Switch Processors

The Cisco ASR 900 Series Aggregation Services Routers represent a cornerstone in modern service provider and enterprise edge networks, designed to deliver high-performance, converged IP and Ethernet services. At the heart of these versatile platforms lies the Route Switch Processor (RSP), the critical engine responsible for system control, packet forwarding, and service intelligence. The Cisco A900-RSP2A-64= is a pivotal component within this ecosystem, specifically engineered to provide a substantial performance uplift, enhanced scalability, and future-ready capabilities for networks undergoing digital transformation and facing exponential traffic growth.

This category encompasses the spare, renewal, or upgrade module designated for the ASR 900 series routers. The "= " suffix in the part number A900-RSP2A-64= signifies a spare unit supplied without the default chassis packaging, making it the standard identifier for procurement as a replacement or enhancement. Investing in this processor category is not merely a hardware upgrade; it's a strategic decision to increase network capacity, enable advanced services like Segment Routing and EVPN, and ensure operational efficiency for years to come.

Deep Dive: The Cisco A900-RSP2A-64= RSP Module

The Cisco A900-RSP2A-64= is the second-generation Route Switch Processor built for the ASR 900 series, succeeding the original RSP modules. It is defined by its 64 Gigabytes (64G) of base system memory, which is a key differentiator. This substantial memory allocation is not just for show; it directly translates to the scale of routing tables, size of forwarding information bases (FIB), number of concurrent services, and overall system stability under heavy load. It is designed to operate in routers such as the ASR 9904, 9906, 9912, and 9922, typically installed in a redundant pair for high availability.

Key Technical Specifications and Architecture

The architecture of the A900-RSP2A-64 is optimized for the demands of the modern network edge. It integrates powerful multi-core CPUs with dedicated hardware for packet processing and deep buffer memory, creating a balanced system for control-plane and data-plane tasks.

Processing Power and Memory Hierarchy

The module features advanced multi-core processors that handle routing protocol calculations, management functions, and service plane operations. The 64GB of DRAM is a foundational resource, supporting massive BGP tables (full Internet views and beyond), extensive MPLS label spaces, and complex QoS policies. This memory scale is essential for operators peering at Internet exchanges or running large-scale MPLS networks.

Forwarding Performance and Capacity

While the system memory supports control-plane scale, the integrated forwarding architecture determines data-plane performance. The A900-RSP2A-64 works in concert with the router's line cards and switch fabric to deliver aggregate system throughput measured in hundreds of gigabits to terabits per second. It enhances the router's ability to process packets at line rate, even with services like ACLs, NetFlow, and QoS enabled.

Hardware Redundancy and Reliability Features

Designed for carrier-class environments, the RSP supports 1:1 redundancy with stateful failover. In a dual-RSP configuration, if the active processor fails, the standby can assume control with minimal service disruption. The module also includes environmental monitoring for temperature and voltage, contributing to the overall mean time between failures (MTBF) and system resilience.

Scaling Internet Peering and Edge Networks

For Internet Service Providers (ISPs) and content providers, the continuous growth of the global BGP routing table (exceeding 900,000 routes) demands processors with immense memory. The 64GB base scale of this RSP ensures the router can hold multiple full-view tables, handle complex routing policies, and maintain stability during route churn events, making it ideal for aggregation and peering edge roles.

Enabling Advanced MPLS and Segment Routing Infrastructures

As networks transition to more scalable and programmable transport paradigms like MPLS Segment Routing (SR-MPLS), the control plane requirements intensify. The A900-RSP2A-64 provides the necessary horsepower to manage thousands of Segment Identifiers (SIDs), support TI-LFA for fast reroute, and orchestrate complex traffic engineering policies across the network domain.

Converged Mobile Backhaul and 5G Ready Networks

The ASR 900 series is a staple in mobile backhaul networks. Upgrading to the A900-RSP2A-64= prepares the network for 5G deployments, which bring increased device density, lower latency requirements, and network slicing. The processor's scale supports the numerous GTP tunnels, finer-grained QoS, and stringent synchronization protocols essential for 4G/LTE-A and 5G xHaul.

Enterprise WAN Aggregation and Data Center Interconnect

Large enterprises with multiple branches rely on WAN aggregation routers to terminate thousands of subscriber sessions (using PPPoE, L2TP) and apply unified security policies. The enhanced memory and processing of this RSP enable support for a larger number of subscribers, VRFs (for multi-tenancy), and encryption tunnels (DMVPN, GET VPN) for secure data center interconnect (DCI).

Benefits of Upgrading to the A900-RSP2A-64=

Migrating from a first-generation RSP to the A900-RSP2A-64= yields tangible operational and strategic benefits that justify the investment.

Substantial Increase in Routing Scale and Convergence

The most immediate benefit is the exponential increase in routing table capacity. This allows networks to accept full Internet routes from multiple peers, leading to optimal path selection and reduced transit costs. Furthermore, the increased processing power accelerates routing protocol convergence times, minimizing network instability during link or node failures.

Enhanced Service Velocity and Feature Enablement

Many advanced software features in Cisco IOS XE, especially those related to segmentation (EVPN-VPWS, MPLS-based Ethernet VPNs) and analytics (NetFlow, IPFIX), are memory and CPU intensive. The A900-RSP2A-64= unlocks the full potential of the router's software license, allowing operators to deploy revenue-generating services without being bottlenecked by hardware limitations.

Improved Network Stability and Predictability

An undersized RSP under constant high memory or CPU utilization can lead to unpredictable behavior and potential outages. The overhead provided by this 64G-base-scale processor ensures headroom for traffic surges and new service introductions, leading to a more stable and predictable network that meets SLAs.

Future-Proofing and Investment Protection

Upgrading the RSP extends the useful life of the entire ASR 900 chassis. It protects the capital investment in line cards, power supplies, and the chassis itself by enabling it to handle next-generation traffic loads and software features, delaying the need for a more costly full platform replacement.

Comparative Analysis: A900-RSP2A-64= vs. Other RSP Options

Understanding where this module fits within the broader RSP portfolio is key to making the right selection.

Comparison with First-Generation RSPs (e.g., A900-RSP2-64)

The A900-RSP2A-64= offers significant architectural improvements over its predecessor, the A900-RSP2-64. While both may share the "64" designation for memory, the "A" version typically features a newer generation of ASICs and CPUs, providing better performance per watt, improved deep buffering, and support for newer software features and line cards that the original RSP may not support.

Scaling Options Within the RSP2A Family

The A900-RSP2A-64= sits within a family that may include variants with different memory capacities or functionalities. For instance, there are RSP2A modules with "Base Scale" and "Enhanced Scale" options. The 64G represents the base scale, suitable for the vast majority of deployments, while enhanced scale options (with potentially more memory) cater to extreme-edge scenarios in top-tier global ISPs.