Introduction to routing / Introduction to routing

Introduction to Static Routing 

Introduction to routing 

6.1.1 

This page will describe routing and explain the differences between static and dynamic routing.
Routing is the process that a router uses to forward packets toward the destination network. A router makes decisions based upon the destination IP address of a packet. All devices along the way use the destination IP address to send the packet in the right direction to reach its destination. To make the correct decisions, routers must learn how to reach remote networks. When routers use dynamic routing, this information is learned from other routers. When static routing is used, a network administrator configures information about remote networks manually.
Since static routes are configured manually, network administrators must add and delete static routes to reflect any network topology changes. In a large network, the manual maintenance of routing tables could require a lot of administrative time. On small networks with few possible changes, static routes require very little maintenance. Static routing is not as scalable as dynamic routing because of the extra administrative requirements. Even in large networks, static routes that are intended to accomplish a specific purpose are often configured in conjunction with a dynamic routing protocol.
The next page will explain static route operations.

Module 6: Routing and Routing Protocols / Overview

Module 6: Routing and Routing Protocols
Overview

Routing is a set of directions to get from one network to another. These directions, also known as routes, can be dynamically given to the router by another router, or they can be statically assigned to the router by an administrator.
This module introduces the concept of dynamic routing protocols, describes the classes of dynamic routing protocols, and gives examples of protocols in each class.
A network administrator chooses a dynamic routing protocol based upon many considerations. These include the size of the network, the bandwidth of available links, the processing power of the routers, the brands and models of the routers, and the protocols that are used in the network. This module will provide more details about the differences between routing protocols that help network administrators make a choice.
This module covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND 640-811 exams. -
Students who complete this module should be able to perform the following tasks:

• Explain the significance of static routing
• Configure static and default routes
• Verify and troubleshoot static and default routes
• Identify the classes of routing protocols
• Identify distance vector routing protocols
• Identify link-state routing protocols
• Describe the basic characteristics of common routing protocols
• Identify interior gateway protocols
• Identify exterior gateway protocols

Enable Routing Information Protocol (RIP) on a router

Module 5 : Summary

Summary

This page summarizes the topics discussed in this module. The default configuration register setting can be changed with the global configuration mode command config-register. The boot sequence for the Cisco IOS can specify the fallback sequence that is used to boot Cisco IOS software. A common fallback sequence would be to load first from flash memory, which is not vulnerable to network failures. The network server would be used next if the flash memory were corrupt. Finally if the first two methods failed the router would boot from ROM. However, the system image in ROM will likely be a subset of the full Cisco IOS image. The command copy running-config startup-config saves the configuration commands in NVRAM. The router will execute the boot system commands as needed in the order in which they were originally entered in the configuration mode. If a configuration register setting is incorrect, the Cisco IOS will not load from flash. To troubleshoot the boot sequence, use the show running-config command and look for a boot system statement near the top of the configuration. If the boot system statement points to an incorrect IOS image, use the no form of the command to delete the statement. The two types of software required to operate a router and a switch are the operating systems and the configuration. The Cisco IOS allows the hardware to function. The configuration file or config is the software that contains the instructions that define how the device is to route or switch the packets that enter the device. The naming convention for Cisco IOS files includes four parts. The first part of the Cisco IOS file name identifies the hardware platform for which this image is designed. The second part of the Cisco IOS file name identifies the various features that this file contains. The third part of the file name indicates the file format. It specifies if the Cisco IOS is stored in flash in a compressed format and whether it is relocatable. The fourth part of the file name identifies the release of the Cisco IOS. As newer versions of the Cisco IOS are developed, the numerical version number increases. The active configuration for a Cisco router is maintained in RAM and the default location for the startup configuration is NVRAM. The copy running-config tftp command can be used to back up copies of the configuration to a TFTP server. Another way to create a backup copy of the configuration is to capture the output of the show running-config command. To do this from the terminal session, copy the output, paste it to a text file, and then save the text file. After the capture is complete, the configuration file needs to be edited to remove extra text. To add a comment, begin a line with an exclamation mark (!).