Graphical network Simulator

1. Graphical Network Simulator
Bahaa Aladdin

2. 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.

3. 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.

4. Dynamips
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.

5. Dynagen
Dynagen is a front-end for use with the Dynamips Cisco
router emulator. It uses an INI-like configuration file to
provision Dynamips emulator networks. It takes care of
specifying the right port adapters, generating and
Dynagen
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.

6. GNS3 also supports other emulation programs, namely
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!

7. Step 1 – Install GNS3
Download program
http://www.gns3.net/
Download IOS for your
router,ipx,etc.. From the internet

8. Step 2 – Install GNS3

9. Step 3 – Defining Cisco IOS files

10. Add router

11. Configuring router

12. IDLE pc

13. 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
WIC-1T (1 serial port)
WIC-2T (2 serial ports)

14. 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)

15. Control IOS image for routers
Edit >IOS images and hypervisor>

16. Hardware emulated by GNS31/3
Cisco Router
Cisco 1700 Series
Cisco 3600 Series
Cisco 2600 Series
Cisco 3700 Series
Cisco 7200 Series
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

17. 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
Qemu/GNS3 emulates ASA5520 (ASA 5520 Series Adaptive Security Appliance)
hardware to run ASA software up to version 8.0(2).
Cisco IDS sensors
Qemu/GNS3 emulates an IDS 4235/4215 Sensor. The software IPS is known to run
with release 6.0.
Juniper routers
JunOS, the Operating System for Juniper routers is based on FreeBSD, an UNIX
Operating System that runs on PCs. At this date all JunOS versions are known to work
in GNS3.

18. 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)

19. Connect 2 routers

20. 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)

21. Connecting GNS3 to Real Networks
Right-click the Cloud and choose Configure.
Click on C1 under Clouds, but choose the NIO
Ethernet tab

22. 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

23. 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.

24. Packet Capture
R.Click on link
Choose Source

25. Packet Capture

26. Example 1

27. Example 2

28. Example 3

29. Good websites
www.gns3.net/
http://www.gns3-labs.com/
gns3-labs
https://www.youtube.com/user/GNS3Vault/videos
300 Learning vedio

30. Bahaa Aladdin