GNS3 – How to build an Internet Lab
Posted by Josh on Wed 16 Jan 2008Categories: Cisco , Cisco Routers , Dynamips , GNS3 - [67] Comments
This tutorial will help you build a basic Internet lab using GNS3 as a WAN simulator. It will be referenced by future tutorials such as how to configure GRE/IPSec VPNs, how to configure a DMVPN (Dynamic Multipoint VPN) and QOS.
The basic steps for building an internet lab with gns3 is to place 4 routers on the lab with one in the middle.
This router represents the internet. Now, connect the other three routers to the Internet with serial cables. Then configure the ISP router ’s serial interfaces with IP addresses that will be used to connect to the other routers. At this point, we will not be configuring the other routers.
January 17th, 2008 at 7:15 am
That’s very practical. I’m sure you could then tweak all sorts of stuff on the interfaces to simulate bandwidth bottlenecks and the like among your three routers.
Good stuff.
January 18th, 2008 at 12:42 am
very good
January 25th, 2008 at 8:48 am
How to configure the 7200 slots before making the n/W
January 30th, 2008 at 8:08 am
I did not have to configure the slots on the routers. Creating serial connections between the routers automatically created necessary interfaces for me.
February 1st, 2008 at 10:28 am
Instead of mousing over the connects you can expand them in the Topology Summary. Great Job BTW.
February 1st, 2008 at 11:20 am
Thanks for the tip Buz!
February 6th, 2008 at 1:20 pm
U such a great guy….Keep up with the good work. I can’t wait to c u try out VPN, QOS and other technologies on this internet lab.
February 13th, 2008 at 11:39 pm
I was following along the video and I get No interface found? Any ideas
February 18th, 2008 at 8:40 am
The video is not working, i like to see this video.
Thanks
Alex
February 18th, 2008 at 10:07 am
Try pressing the play button. If it still doesn’t work, let me know.
Josh
February 26th, 2008 at 11:57 pm
[...] In Part 1 of the Internet lab tutorial, we created a virtual "internet" using gns3. We built the infrastructure and configured a router to represent "The Internet" (ISP). This time, you will add switches and configure the internet routers at each customer site. Other tutorials will follow that use these two tutorials as a foundation. [...]
March 5th, 2008 at 10:16 pm
[...] This tutorial is part one of a two part series. If you have not already been through the internat lab series, I recommend watching them before starting the GRE/IPSec tutorials – Internet Lab Part 1 and Internet Lab Part 2. [...]
March 8th, 2008 at 11:15 pm
[...] the internat lab series, I recommend watching them before starting the GRE/IPSec tutorials – Internet Lab Part 1 and Internet Lab Part [...]
March 10th, 2008 at 11:48 pm
The first time I tried this lab scenario it worked like a charm but then I started having problems with cpu usage. I could only run two of the routers before it comes to a halt. I tried to reinstall GNS3 but it didn’t help. I followed all the steps during the initial setup including setting up idlepc. I don’t know if I should change it, and I am not even sure how. Anybody has an idea? Thanks.
A big thank you to the Admin. This website rocks and definitely deserves to be among the top 20 sites (for me it’s #1). Thank you so much for sharing your knowledge.
March 11th, 2008 at 12:36 am
Thank you for the kind words. I am glad the site has helped you.
I have had this problem with different bad idlepc values. It is really hit and miss. Sometimes, I am able to get a good idlepc value immediately, other times, I have to restart the lab several times and try again.
Make sure you are watching your CPU utilization when applying your idlepc values. It helps to find a good value.
Josh
March 13th, 2008 at 8:55 am
[...] How to build an Internet Lab [...]
March 17th, 2008 at 3:14 pm
Sorry for bothering with these basic question. I am also hoping someone here had to figure out a way around this issue before. Here is my question(s):
How do you reset idlepc value after already setting it once? Is it possible to reset idlepc at all? Do I have to delete the lab and start from scratch again. For some reason the value I picked the first time when I created the lab does not seem to work now. I might have to delete all the labs I’ve created since they all share the same idlepc value. I tried to delete the value in the .ini file but that didn’t work. when I try ‘idlepc get R1′, I get something like ‘R1 already has an idlepc value applied’. Thanks for any suggestions.
March 17th, 2008 at 9:54 pm
Mona,
The idle-pc value is stored with the IOS image. Try this inside GNS3…
1) Make sure you are in design mode
2) Go to Edit > IOS Images and Hypervisors
3) Double-Click on the the image you are using
4) Clear the idle-pc value
5) Save
Josh
March 18th, 2008 at 4:27 pm
Got it. Thanks Josh. I actually tried to do that before I posted the question but for some reason the old idlepc value just didn’t want to go away. Just for the sake of learning, could that be because I had other .ini files /labs with the same idlepc value in the same folder (and which I deleted before I received your recommendation)? But this time I followed your advice and took my time comparing the idlepc values. I think I got a good one.
Thanks very much again for your time and effort.
March 19th, 2008 at 12:02 am
Mona,
I am glad to hear it is working out for you. I guess it could be the old .ini files causing problems. It is really hard to tell…
If you do find out what the problem was, please post the solution.
Josh
March 28th, 2008 at 2:03 pm
One more thing regarding idlepc…I have found that starting and consoling into each device at a time helps a lot. From simulation mode, play R0 (for example), then console into it…watch cpu usage go down in seconds. Once the interfaces are all initialized you will notice a dramatic decrease in cpu usage (from about 50+ to single digits in my case). Do the same thing with R1, and R2…etc. It worked for me. It might be a good idea for labs with a large number of devices.
April 15th, 2008 at 11:01 am
hiii
how can i save my running config to run it again in the future ???
April 15th, 2008 at 1:16 pm
@Sameh, honestly…I have not tried to save the config with GNS3. I will look into it. – Josh
April 21st, 2008 at 7:53 pm
Gr8 work. I am waiting for VPN and QOS..
May 21st, 2008 at 2:43 am
Thanks for this great tutorial..
Can you help me on my problem w/ GNS3 simulating the PIX, it goes like this..
When I insert a PIX then start the service, my CPU boost to 100%, how can I lower the CPU usage?
Thank you.
June 2nd, 2008 at 5:28 am
[...] labs were built based on BlindHogs’ How to build an Internet Lab Part 1 & Part [...]
June 12th, 2008 at 7:06 pm
GNS3 has rocked ever since I’ve been using.
Useful tips from Josh regarding Idle PC.
I faced the same problem as Mona, in the beginning I could use very few routers.
To overcome this limitation, I started using GNS3 in VMWare, it has helped me a lot since then.
Now, with Idle PC Values, it has just got better.
Thank you Josh for these valuable inputs and this forum surely rocks…
Cheers !
June 12th, 2008 at 7:10 pm
With regards to saving configurations, it is pretty easy in GNS3.
U need to be in Emulation Mode and click on the button to the left of “Telnet to all IOS” button.
this will help you extract the configs to the folder of ur choice.
You can also boot a device with a specific start up config.
June 12th, 2008 at 8:53 pm
@Farhan – Thank you for the great tip!
Josh
June 17th, 2008 at 8:12 pm
[...] labs were built based on BlindHogs’ How to build an Internet Lab Part 1 & Part [...]
July 9th, 2008 at 8:36 pm
Man that was great stuff, i have done my site to Site VPN with this info. many many thanks
cheers
sri
July 13th, 2008 at 1:31 am
@Srinivas – Glad it helped!
Josh
July 22nd, 2008 at 1:37 pm
Hello all I am a Newbie to this simulator and I have a question where is the first tutorial?,like for a beginner thanks
October 12th, 2008 at 12:12 am
Hi ppl,
i installed GNS3 and created my topology, but i am not able to connect/console to the devices need help.
and my CPU running 100% any tip?
October 13th, 2008 at 10:55 am
Praveen,
You might look at some of our other GNS3 tutorials. If you still have issues, send me an email.
Josh
November 20th, 2008 at 10:57 am
Hi Im new to blindhog and GNS3. very good tutorial.
when i start 4 routers my system becomes slow. i hardly installed server 2003 as dual OS. still my i cant work on it as its slow used idl pcs …..
any help or suggestion. i am having 640-802 exam within 10days time
November 20th, 2008 at 11:53 am
remo,
Open the task manager on your pc and try other idle pc values. You have to keep trying until you find one that works.
Then apply that value to the other routers.
Actually, I normally start with 1 router and find an idle pc value for that particular IOS. Then start building larger labs … saves time and is more controlled environment.
Josh
November 20th, 2008 at 1:58 pm
Thank you Josh
I am using different routers. i will try using only one router and try.
thanks agin
November 22nd, 2008 at 2:05 pm
Hi Josh
I am wondering if i can choose slots when connecting routers via serial. I am using GNS3 0.5 beta version. How can I connect two routers via ethernet to a network using GNS3 simulator.
Thak you
November 22nd, 2008 at 2:20 pm
Hello josh
when I open consoles for 2/3 routers at a same time the windows says TELNET LOCAL HOST
is it correct or do i have to configure something else. I am running GNS3 on win2003 server.
I got this doubt because when Im working some times the consoles get closed and get a message on dynagen saying dynamips server crashed error …….
some times my PC gets hanged so can i set the pirority of dynamips-wxp.exe to real time.
many doubts as i have CCNA exam in a week time
Thank You
November 22nd, 2008 at 7:14 pm
IF josh is not here
anyone can reply to my comments.
November 22nd, 2008 at 7:14 pm
IF josh is not here
anyone can reply to my comments.
November 22nd, 2008 at 9:45 pm
Remo,
Sorry for the delay in answering your questions. In the future, you should visit http://7200emu.hacki.at if your patience runs short.
“I am wondering if i can choose slots when connecting routers via serial. I am using GNS3 0.5 beta version. How can I connect two routers via ethernet to a network using GNS3 simulator.”
Yes. Right click on your router and click configure. Select the ’slots’ tab to make changes to your slots.
If you want to choose the slots configured in the router when connecting routers…click the ‘Add a Link’ icon and select ‘manual’ instead of serial or ethernet.
I honestly don’t know what to say about your second question…it doesn’t really make a lot of sense to me. Sorry. You should take your question to http://7200emu.hacki.at for a quicker response.
Josh
November 23rd, 2008 at 8:23 am
Thank you josh for the reply
I am sorry I just worried abt the time i have running short of time not patience.
brillant ur ans
“If you want to choose the slots configured in the router when connecting routers…click the ‘Add a Link’ icon and select ‘manual’ instead of serial or ethernet”
worked for me
i configured rip but still i have errors when used show ip route. if u want i can send snapshots to ur email
again thanks alot for ur help and for the link
February 22nd, 2009 at 1:47 am
Thanks for your time and efforts putting all these videos.
What router you use for the ISP? 7200?
Archie
February 24th, 2009 at 9:53 pm
Archie,
I think I may have used a 7200, but you can use almost any router. Provided it has enough interfaces. I like the 3640s and 1700s because they require less CPU and memory resources.
Josh
March 6th, 2009 at 3:52 am
hi all
i am new of using the gns3 for the pix firewall. i sm getting confusion. i installed putty also. i need all help videos for download.please send me link to mail mail id.
shaah_k@yahoo.co.in
thanking you
March 12th, 2009 at 5:08 am
Here are all the pix / pemu videos on blindhog. http://www.blindhog.net/category/pemu/
Josh
March 12th, 2009 at 9:42 pm
Hi,I am following your video here to build my lab. I do not see Emulation Mode button in my GNS3 on my pc. How to start routers? Am I missing something?
Thank you.
April 11th, 2009 at 10:32 am
Josh> gj
dips> I think the video was made ages ago and u run the newest version of GNS3, where that buttons was eliminated (automated), therefore u r directly in emulation mode at the start.
If u wanna start a router then right click on it and click Start.
hope helped
c u all
Balazs from Hungary
April 13th, 2009 at 6:03 am
Balazs,
You are correct. This video was made with an older version of GNS3. The Emulation mode button was removed in more recent versions.
GNS3 emulation and design modes have been merged together.
Josh
April 20th, 2009 at 7:27 pm
Josh,
Quick question please. You seem to know a great deal about the GNS3. If I am going to try to run this for ccie prep and would like to get to 6 routers, what would be the best way to get that done? VMware and some particular host OS? How about a dedicated external hypervisor? Any input would be appreciated! Hats off to you for helping everyone with this.
April 21st, 2009 at 1:22 pm
Steller,
Personally, I am not sure exactly what you will need, but I have found that 4GB RAM and a dual-processor or dual-core processor are needed at a minimum (for vmware and gns3 running at the same time)
If you plan on using Cisco Call Manager in VMWare. Stay away from AMD processors. CUCM will not install in VMWare if you have an AMD host processor.
I have not had great luck with external hypervisors. If you are building a huge lab, they are needed. But then again, I haven’t spent lots of time trying to make them work for me. Most of my labs are only 4-5 routers.
Also, use Linux as your host. Dynamips on windows uses cygwin (linux emulation) and it just does not work as well. If you need windows … run a windows virtual machine in vmware.
I have been working on a tutorial series for a voice lab using gns3 and vmware. Although it has a voice slant, it is still good information for building any cisco lab using vmware and gns3.
Hope that answers your questions.
Josh
May 5th, 2009 at 8:14 am
Hi All
Using 3640 after router reboots when i do sh ver i see only i slot instead i have selected two slots in configure Tab. I did sh diag it is showing Unknown in one of the slots. Please guide.
May 18th, 2009 at 12:37 am
thank its a nice post
May 18th, 2009 at 12:39 am
but what about DCE configuration? dont we have to make router DCE or DTE
June 20th, 2009 at 7:28 pm
I finished lab1 and extracted the startup configs to a folder.
Next time when i start the lab1 ,i am loosing the configs in my setup and need to reconfigure again.
Is there a way i can jump start my lab1 with earlier stored startup configs .
Thanks
venu
July 29th, 2009 at 9:59 am
[...] http://www.blindhog.net/gns3-how-to-build-an-internet-lab/ [...]
September 7th, 2009 at 11:51 am
Hi,
I am currently studying for CCNA exam and I am just wondering if there is a way I can learn to do labs for CCNA. I was hoping to find some videos here. If gns3 is used that would be great.
Thanks
September 10th, 2009 at 5:57 am
Hi All,
I would like to know how to configure the GNS3 Router to connect to the internet, so that the vmware virtual pcs can access the internet via the GNS3 router.
My host operating system connects to the internet either through a proxy server or through my data card connection.
currently my diagram is
R0 => SW0 => C0(vmware pc-ubuntu)
Please suggest
Thanks,
Subhash
October 6th, 2009 at 12:13 am
Hi All,
I would like to know how to configure and add Router and L2, L3, MLS Switch.
October 7th, 2009 at 11:15 pm
in your video, i found button called “emulation mode” , on my GNS3, i dont’see that button. what do i do?
December 21st, 2009 at 7:17 pm
hey, i am new to GNS and preparing for CCNP routing exam, i am facing problem with idlepc thing, if i use only one router and set idlepc value, it works fine but when i try to connect 4 routers of same series, it doesn’t. i want to ask, do i need to configure idlepc value on every router or what? kindly explain because when i run 4 routers, my CPU usage boost to 100%….
January 12th, 2010 at 6:36 pm
I THANK´S.
January 24th, 2010 at 12:48 am
hi,
to josh or anyone who knows the answer,
Actually I have set my idlepc value, however I could not see the cpu utilization window when I applyed my idlepc values.
many thanks to everybody
January 24th, 2010 at 2:20 am
hi there,
Can anyone help me to add a serial interface for my 1700 and 2600 routers? In fact after I choice my routers and click on the add link button to connect between the two routers by chosing the serial interface,I get this message (no interface available.
Many thanks for all of you.
January 24th, 2010 at 11:54 pm
Khaled,
If you are using linux – Open a terminal window and type ‘top’ to see the cpu utilization.
If you are using windows – Look at the Task Manager.
Josh