(32 votes, average: 4.19 out of 5)
Loading ...Wed 16 Jan 2008
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