# Chassis Overview

Two models are available:

- E120 router
- E320 router

Both models use the same software and share a system architecture and common components:

- Switch route processors (SRPs)—Perform system management, routing table calculations maintenance, forwarding table computations, and other control plane functions
- Switch fabric modules (SFMs)—Create a distributed shared memory switching fabric
- Line modules (LMs)—Are frame processing and forwarding engines for IOAs
- Input/output adapter (IOA)—Provide the physical connection to the network via 10–Gigabit Ethernet, Ethernet, ATM, and Packet over SONET (PoS) interfaces
- Power modules—Distribute redundant power feeds through the system to all components

## E320 Model

A fully configured E320 router consists of 2 switch route processors (SRPs), 3 switch fabric modules (SFMs), 12 line modules, and up to 2 I/O adapters (IOAs) per line module. See Figure 1 and Figure 2.

An IOA shelf (bracket) can be installed on a slot-by-slot basis to create an upper IOA bay and lower IOA bay, enabling you to use up to two IOAs in the same slot. This architecture enables you to combine different IOA types in the same slot and to support oversubscribed configurations.

| Note: The routers illustrated in this book might look different than your router due to configuration variations.

Figure 1: E320 Router, Front View

Figure 2: E320 Router, Rear View

## E120 Model

A fully configured E120 router consists of 2 switch route processors (SRPs), 3 switch fabric modules (SFMs), 6 line modules, and up to 2 I/O adapters (IOAs) per line module. See Figure 3 and Figure 4.

An IOA shelf (bracket) can be installed on a slot-by-slot basis to create a left and right IOA bay, enabling you to use up to two IOAs in the same slot. This architecture enables you to combine different IOA types in the same slot and to support oversubscribed configurations. Air is pulled in from the right of the router by the fan tray and is exhausted out the left side.

| Note: The routers illustrated in this book might look different than your router due to configuration variations.

Figure 3: E120 Router, Front View

Figure 4: E120 Router, Rear View