7600-ES20-GE3CXL Cisco 20 Ports Managed Switch Ethernet Services 20G Line Card

The Cisco 7600-ES20-GE3CXL represents a critical component in the robust Cisco 7600 Series Routers ecosystem, designed for high-density aggregation and core layer services. This 20-Gigabit Ethernet line card is engineered to deliver exceptional Layer 3 switching performance, scalability, and reliability for demanding enterprise and service provider networks. Featuring 20 fixed Gigabit Ethernet ports with Small Form-Factor Pluggable (SFP) transceiver slots, it provides unparalleled flexibility in media and distance selection, supporting a wide array of SFP modules for copper or fiber connectivity. As part of the esteemed 7600 series, the ES20-GE3CXL card enables organizations to consolidate services, enhance network intelligence, and future-proof their infrastructure with advanced features like hardware-based IP Version 6 (IPv6) routing and Multicast VPN (MVPN) support.

Technical Specifications and Hardware Architecture

Understanding the underlying hardware architecture of the Cisco 7600-ES20-GE3CXL is key to appreciating its capabilities within the chassis. This line card is meticulously designed to integrate seamlessly into the Cisco 7600 router's distributed forwarding model.

Core Hardware Components

The card leverages a high-performance ASIC (Application-Specific Integrated Circuit) design dedicated to packet forwarding and feature acceleration. This ensures that complex services like Access Control Lists (ACLs), Quality of Service (QoS) marking and policing, and NetFlow statistics are executed in hardware without impacting the overall system performance.

Forwarding Engine and Memory

At the heart of the ES20-GE3CXL is a dedicated forwarding engine equipped with ample TCAM (Ternary Content-Addressable Memory) and DRAM. TCAM is crucial for high-speed lookups of complex routing tables, ACLs, and QoS policies. This hardware-based forwarding paradigm guarantees wire-speed performance on all 20 ports simultaneously, even with multiple advanced services enabled.

Port Density and Configuration

The card's fixed configuration of 20 Gigabit Ethernet ports is presented through SFP slots (often denoted as 20 x 1GE SFP). This design offers significant advantages over fixed-media ports, as network administrators can select the appropriate SFP transceiver—be it short-reach (SX), long-reach (LX/LH), extended reach (ZX), or copper (T)—for each specific link, optimizing for distance, media type, and cost.

Performance Metrics and Scalability

The "20G" in the product name refers to its full-duplex aggregate throughput capacity, supporting high-speed data transfer critical for backbone and distribution layer applications. The card is engineered to handle massive routing tables, supporting hundreds of thousands of IPv4 and IPv6 routes, making it suitable for full Internet routing table peering.

Key Features and Functional Capabilities

The Cisco 7600-ES20-GE3CXL is more than just a collection of ports; it is a sophisticated switching and routing module that brings a comprehensive suite of features to the 7600 chassis.

Advanced Layer 3 Switching and Routing

As a true Layer 3 switch module, it supports a full suite of unicast routing protocols including OSPF, EIGRP, IS-IS, and BGPv4. Its hardware-accelerated routing ensures minimal latency for packet forwarding decisions. Furthermore, it provides robust multicast routing support with protocols like PIM-SM, PIM-SSM, and PIM-Bidir, which is essential for content distribution, financial data feeds, and video conferencing applications.

Comprehensive Quality of Service (QoS)

The module implements a sophisticated QoS architecture based on the DiffServ model. It supports classification, marking, policing, shaping, and queuing on a per-port basis. Advanced capabilities like Hierarchical QoS (H-QoS) allow for granular bandwidth management, enabling service providers to offer tiered services and enterprises to prioritize mission-critical applications.

Granular Traffic Management

With support for multiple egress queues per port, the card can manage traffic bursts effectively and ensure low latency for priority traffic such as Voice over IP (VoIP) or real-time video, even during periods of congestion.

Enhanced Security and ACLs

Security is enforced at wire speed through the use of extended and named ACLs for IPv4 and IPv6. These ACLs can be applied in the ingress or egress direction to filter traffic, protect infrastructure, and enforce security policies. Integration with features like Control Plane Policing (CoPP) helps shield the router's CPU from malicious traffic.

High Availability and Reliability

Network uptime is paramount, and the ES20-GE3CXL is built with carrier-class reliability. It supports in-service software upgrades (ISSU) when used in a compatible supervisor and chassis configuration, allowing for software patches and upgrades without disrupting network services.

Hardware Redundancy and Failover

While the line card itself is a single point of failure within a slot, its design complements the overall redundancy of the Cisco 7600 chassis, which supports dual supervisor engines, redundant switch fabric, and redundant power supplies. Protocols like Graceful Restart for OSPF and BGP ensure minimal impact during failover events.

Deployment Scenarios

The versatility of the Cisco 7600-ES20-GE3CXL allows it to serve in several critical roles within a network's architecture. Its high port density and advanced features make it ideal for specific deployment models.

Enterprise Network Core/Distribution Layer

In large campus or enterprise networks, this module can act as a powerful distribution or core switch. It aggregates traffic from multiple access layer switches (such as Cisco Catalyst 3750 or 4500 series), provides inter-VLAN routing, enforces security and QoS policies, and serves as a gateway to the data center and WAN.

Service Provider Edge Aggregation

For service providers, the card is perfectly suited for aggregating customer traffic from multiple access devices. It can terminate customer VLANs, apply per-subscriber QoS and security policies, and hand off aggregated traffic to the core network. Its support for MPLS and VPN services is a key asset in these scenarios.

MPLS VPN PE and VRF Support

The module fully supports MPLS forwarding and Virtual Routing and Forwarding (VRF) instances, enabling it to function as a Provider Edge (PE) router in Layer 3 MPLS VPN networks. This allows a single physical router to maintain separate routing tables for multiple customers, ensuring security and traffic isolation.

Data Center Aggregation

While later technologies have evolved for the data center, the 7600 with the ES20-GE3CXL card found use in traditional data center designs for aggregating server farm access switches, providing default gateway services, and connecting to core/wan routers.

Fabric Connectivity and Bandwidth

The card connects to the chassis's central switch fabric via a fabric channel. With a Supervisor 720, it can leverage the full 20-Gigabit capacity. It's crucial to verify that the installed supervisor and fabric configuration support the required bandwidth for the line card to prevent any internal bottlenecks.