Graphical network Simulator

Graphical network Simulator

Graphical Network Simulator

Bahaa Aladdin

What is GNS3 ?

• GNS3 is a graphical network simulator that allows simulation of complex

networks

• To provide complete and accurate simulations, GNS3 is strongly linked with:

• Dynamips , a Cisco IOS emulator

• Dynagen , a text-based front end for Dynamips

• Qemu , a generic and open source machine emulator and virtualizer

• VirtualBox , a free and powerful virtualization software

• GNS3 is an excellent complementary tool to real labs for network engineers, administrators and people wanting to study for certifications such as Cisco

CCNA, CCNP, CCIP and CCIE as well as Juniper JNCIA, JNCIS and JNCIE

• It can also be used to experiment features of Cisco IOS, Juniper JunOS or to check configurations that need to be deployed later on real routers

• This project is an open source, free program that may be used on multiple

operating systems, including Windows, Linux, and MacOS X

GNS3 is based on Dynamips and Dynagen (a text-based front-end for Dynamips) to create a complete virtual Cisco network, adding many additional features and

most importantly making it easy to create, change and save your network topologies

Dynamips is the core program that allows IOS

emulation GNS3 runs on top of Dynamips to create a more user friendly, graphical environment

Dynamips is a software that emulates Cisco IOS on a

traditional PC It has been made by Christophe Fillot who started his work in August 2005 The last official release of Dynamips supports Cisco 7200, 3600 series (3620, 3640 and 3660), 3700 series (3725, 3745), 2600 series (2610 to 2650XM, 2691) and 1700 series It is very popular with people studying for CCNA (Cisco

Certified Network Associate), CCNP (Cisco Certified

Network Professional) and CCIE (Cisco Certified

Internetwork Expert) certification exams

Cisco Dynamips

end for use with the -

matching up those pesky NIO descriptors, specifying

bridges, frame-relay, ATM switches, etc It also provides

a management CLI for listing devices, suspending and reloading instances, determining and managing idle-pc values, performing packet captures, etc

Dynagen

Qemu, Pemu and VirtualBox These softwares are used

to emulate Cisco ASA and PIX firewalls, Cisco IPS,

Juniper routers as well as hosts (Linux, Windows, Mac

OS X, FreeBSD etc.) GNS3 makes all of this emulation

magic work together and allow you, for instance, to

have your Cisco router talking to your Linux host The possibilities are almost endless!

Step 1 – Install GNS3

Download program

http://www.gns3.net/

Download IOS for your

router,ipx,etc From the internet

Step 2 – Install GNS3

Step 3 – Defining Cisco IOS files

Add router

Configuring router

IDLE pc

Add Wic

The 1-port serial WAN interface card (WIC-1T)

provides serial connections to remote sites or legacy serial network devices such as

Synchronous Data Link Control (SDLC) concentrators

WIC cards

serial port)

1 (

T

2

-WIC

ADD NM

Network Modules

NM-1E (1 Ethernet port)

NM-4E (4 Ethernet ports)

NM-1FE-TX (1 FastEthernet port)

NM-16ESW (switch module: 16

FastEthernet ports)

Control IOS image for routers

Edit >IOS images and hypervisor>

Cisco Catalyst Switches

At this moment, it is not possible to emulate Catalyst switches

with Dynamips/GNS3 This is due to the impossibility to

emulate ASIC processors used in those type of devices

However you can use the EtherSwitch module with 2600s,

3600s and 3700s Serie

Hardware emulated by GNS3-2/3

Cisco PIX firewalls

A special version of Qemu called PEMU is embedded into GNS3 for emulating the PIX

525 Security Appliance PIX software up to version 7.2(4) is supported

Cisco ASA firewalls

Series Adaptive Security Appliance)

5520 (ASA

5520 ASA

emulates

3 /GNS

Qemu

) 2 ( 0 8

up to version

hardware to run ASA software

Cisco IDS sensors

The software IPS is known to run Sensor

4215 /

4235 IDS

emulates an

3 /GNS

Qemu

with release 6.0.

Juniper routers

, an UNIX FreeBSD

, the Operating System for Juniper routers is based on

JunOS

Operating System that runs on PCs At this date all JunOS versions are known to work

in GNS3.

Hardware emulated by GNS-3/3

Hosts

Thanks to Qemu and VirtualBox, GNS3 can run many operating

systems like Linux or Windows as well as a lot of appliances To

save you time, we provide ready-to-use Qemu and VirtualBox

images that integrate Linux Microcore (command line) and Linux

Tinycore (small graphical interface) These images are designed

to not use much memory, allowing you to run many virtual

hosts They include the following tools and features:

Console support

IPv6 support

iperf, tcpdump, iproute2 and iptables

SSH and telnet servers

D-ITG (Distributed Internet Traffic Generator)

Connect 2 routers

Using terminal programs with GNS3

The current preconfigurated terminal

commands are:

Putty (Windows 64 bits)

Putty (Windows 32 bits)

Putty (Windows, included with GNS3)

SecureCRT (Windows 64 bits)

SecureCRT (Windows 32 bits)

TeraTerm (Windows)

Telnet (Windows)

xterm (Linux/BSD)

Putty (Linux/BSD)

Gnome Terminal (Linux/BSD)

KDE Konsole (Linux/BSD)

Terminal (Mac OS X)

iTerm (Mac OS X)

Connecting GNS3 to Real Networks

Right-click the Cloud and choose Configure

Click on C1 under Clouds, but choose the NIO

Ethernet tab

Memory Usage

The Ghostios option can significantly reduce the amount of real host RAM needed for labs

with multiple routers running the same IOS image

The “sparsemem” feature does not conserve real memory, but instead reduces the amount

of virtual memory used by your router instances

CPU usage

We talked about CPU Usage a bit earlier when we learned how

to determine idlepc values Without idlepc values configured,

you may have noticed that your system’s CPU was running at 100% This is because Dynamips, the core emulator running

under GNS3, does not know when the virtual router is idle, and when it is performing useful work The “idlepc” command

performs analysis on a running image to determine the most likely points in the code that represent an idle loop in the IOS process Once applied, Dynamips “sleeps” the virtual router

occasionally when this idle loop is executed This significantly reduces CPU consumption on the host without reducing the virtual router’s capacity to perform real work.

Packet Capture

R.Click on link

Choose Source

Packet Capture

Example 1

Example 2

Example 3

Good websites

www.gns3.net/

labs.com/

3

-http://www.gns

gns3-labs

Vault/videos3

https://www.youtube.com/user/GNS

300 Learning vedio

Bahaa Aladdin