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Introduction to Routing and Packet Forwarding
Routing Protocols and Concepts – Chapter 1

ITE PC v4.0 Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

1

Objectives
Identify a router as a computer with an OS and hardware designed for the routing process. Demonstrate the ability to configure devices and apply addresses. Describe the structure of a routingtable. Describe how a router determines a path and switches packets

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

2

Introduction
Router is a computer Basic purpose of a router –responsible for interconnecting networks by selecting the best path for a packet to travel and forwarding packets to their destination Routers generally have 2 connections: -WANconnection (Connection to ISP) -LAN connection

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

3

Introduction
Routers examine a packet’s destination IP address and determine the best path by enlisting the aid of a routing table

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

4

Inside The Router
Routercomponents and their functions” CPU - Executes operating system instructions Random access memory (RAM) - Contains the running copy of configuration file. Stores routing table. RAM contents lost when power is off Read-only memory (ROM) - Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program. Non-volatile RAM (NVRAM) - Stores startup configuration. This mayinclude IP addresses (Routing protocol, Hostname of router) Flash memory - Contains the operating system (Cisco IOS) Interfaces - There exist multiple physical interfaces that are used to connect network. Examples of interface types: -Ethernet / fast Ethernet interfaces -Serial interfaces -Management interfaces
CCNA2 - Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

5Inside The Router
Router components (Logically)

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

6

Inside the Router – cont’
Router components (physically)

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

7

Inside The Router: Boot-up Process
Major phases to the router bootup process Test router hardwarePower-On Self Test (POST) Execute bootstrap loader Locate & load Cisco IOS software -Locate IOS -Load IOS Locate & load startup configuration file or enter setup mode -Bootstrap program looks for configuration file

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

8

Inside The Router: Boot-up Process
Verify the router boot-up process: – The show versioncommand is used to view information about the router during the bootup process. – Information includes: Platform model number Image name & IOS version Bootstrap version stored in ROM Image file name & where it was loaded from Number & type of interfaces Amount of NVRAM Amount of flash Configuration register

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public9

Inside The Router: Boot-up Process

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

10

Router Interfaces
Router Interface is a physical connector that enables a router to send or receive packets Each interface connects to a separate network Consist of socket or jack found on the outside of a router Types of router interfaces: -Ethernet-Fastethernet -Serial -DSL -ISDN -Cable

CCNA2 - Chapter 1

© 2007 Cisco Systems, Inc. All rights reserved.

Cisco Public

11

Router Interfaces
Two major groups of Router Interfaces –LAN Interfaces: Are used to connect router to LAN network Has a layer 2 MAC address Can be assigned a Layer 3 IP address Usually consist of an RJ-45 jack 2 types of connectors can be used: Straight through...