Cisco Systems Router 1600 User Manual

Cisco 1600 Series Router Architecture

Cisco 1600 Series Router Architecture

Table of Contents

Cisco 1600 Series Router Architecture............................................................................................................1

Introduction.............................................................................................................................................1

Hardware Overview................................................................................................................................1

Block Diagram...........................................................................................................................2

Memory Details......................................................................................................................................3

Boot Sequence........................................................................................................................................5

Packet Switching........................................................................................................................7

Related Information..............................................................................................................................10

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Cisco 1600 Series Router Architecture

Introduction
Hardware Overview

Block Diagram

Memory Details
Boot Sequence

Packet Switching Related Information

Introduction

This document is an overview of the hardware and software architecture of the Cisco 1600 Series Routers.

Hardware Overview

Cisco 1600 Series routers are composed of the following router models:

Cisco 1601 and 1601R: Ethernet/Serial Modular Router•
Cisco 1602 and 1602R: Ethernet/Serial Modular Router with 56K CSU/DSU (4−wire)•
Cisco 1603 and 1603R: Ethernet/ISDN−BRI (S/T interface) Modular Router•
Cisco 1604 and 1604R: Ethernet/ISDN−BRI Modular Router with NT1 (U interface)•
Cisco 1605R: Dual Ethernet Modular Router•

In addition, all the 1600 router models have one WAN interface card (WIC) slot where you can insert one of
the WAN Interface Cards for the Cisco 1600 Series.
For more information, see Cisco 1600 Series − Modular Desktop Access Routers Product Catalog.

Figure 1: Cisco 1601 and 1601R Rear Panel

Figure 2: Cisco 1602 and 1602R Rear Panel

Figure 3: Cisco 1603 and 1603R Rear Panel

Cisco 1600 Series Router Architecture

Figure 4: Cisco 1604 and 1604R Rear Panel

Figure 5: Cisco 1605R Rear Panel

The Cisco 1600 series routers are either run−from−Flash or run−from−RAM models. Router model names
with an R are run−from−RAM routers; all other models are run−from−Flash. A more detailed description
of these two memory architectures are described in Cisco 1600 Series Memory Architecture and Comparison
of Cisco 1601−Cisco 1604, and Cisco 1605−R.

Block Diagram

The following figure represents the basic block diagram of the 1600 router:

The basic characteristics and functions of each block in this platform can be summarized as:

Processor: The processor used in the 160x series is the Motorola 68360 Complex Instruction Set

•

Computer (CISC). The main job of the processor is to load instructions defined in Cisco IOS
software from PCMCIA Flash or from RAM (for the R models) and execute them, which basically
involves some manipulation of data. The M68360 is an embedded controller, and has a 32−bit
address, a 32−bit data bus, a 33 MHz internal clock, and a built−in Serial Communication Channels
(SCC).

Memory: This is discussed in more detail in the Memory section below.•

Buses are used by the CPU for accessing various components of the system and transferring

•

instructions and data to or from specified memory addresses.

CPU Bus is for high speed operations, with direct processor access. It has a 32−bit address

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and 32−bit data at 33 MHz. These include access to dynamic RAM (DRAM), Boot ROM,

Cisco 1600 Series Router Architecture

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