This blog is for the users who want to simulate the router environment in GNS3VM irrespective of the vendors (Cisco, Juniper, etc.) The previous blog explained how to install and configure the GNS3 VM. It only facilitates a platform to use Cisco IOS but does not provide any Cisco IOS itself if someone wants to use any Cisco device in GNS3, they must install that device’s IOS first. GNS3 does not include any Cisco IOS in its default installation since Cisco IOS has copyright laws to protect it. Cisco uses proprietary software called Cisco IOS for its routers and switches. 1 - 10 CCNA 2: Routers and Routing Basics v 3.1 - Lab 5.2.6b Copyright © 2003, Cisco Systems, Inc.GNS3 (Graphical Network Simulator-3) is a network simulator software used to simulate routers, switches, and other networking devices, and it runs on Cisco IOS. Instructions are available at the end of this lab. Note: Erase and reload the router to prevent problems that may be caused by residual configurations. Start a HyperTerminal session as performed in the Establishing a HyperTerminal session lab. Any other router used may produce slightly different output. The configuration output used in this lab is produced from 1721 series routers.
Refer to the chart at the end of the lab to correctly identify the interface identifiers to be used based on the equipment in the lab. Setup a network as displayed in the figure. Depending on the size of the IOS image and the console baud rate, the download can take 20 minutes or more. Because this procedure relies on the console speed of the router and the serial port of the PC, it can take a long time to download an image. This procedure can also be used where there are no Trivial File Transfer Protocol (TFTP) servers or network connections, and a direct PC connection (or through a modem connection) to the router console is the only viable option. Xmodem can be used on a group of routers (listed below) and is used in disaster recovery situations where the router has no valid Cisco IOS software to boot from and hence, only boots up in ROMmon. If the procedure cannot be avoided, this lab explains how to use the xmodem command at the console to download Cisco IOS® Software using the ROM monitor (ROMmon). Background/Preparation This is a process that is needed only as an emergency when a user has deleted or erased the IOS and there is no possibility of being able to download a new version of the IOS from a TFTP server. Learn how to avoid having to use Xmodem to restore an IOS file.Recover a Cisco router stuck in ROM monitor (ROMmon) mode.Lab 5.2.6b Managing IOS Images with ROMmon and Xmodem Objective