General
What is Jimsim?
Jimsim is a network simulator that I wrote about a year ago just for fun. It emulates three
routers with a very familiar Cisco IOS like interface. The three routers only have Ethernet interfaces,
which are connected to four separate virtual networks. See the About Jimsim page for
a list of supported features.
Is it free?
Jimsim is free to download and use for personal use. Commerical use and reselling is prohibited. You
are also not allowed to redistribute the binary (or source) versions.
Why did you create this software?
Someone told me that I couldn't do it. The jury is still out on if they were right or not.
Can I email you?
Sure, see the contact link in the bar to the left.
Are you going to release the source?
I haven't decided yet.
What's it good for?
For someone first learning how to use a Cisco router, this emulator can show them how to get started.
The main features like command line completion, ethernet interfaces, ping, cdp, and basic EIGRP
routing are all present and working. See the About Jimsim page for
a list of supported features.
Why don't you have feature XYZ?
For free, what did you expect?
Can I use Jimsim to teach my class?
Contact me and we can discuss.
Installation
How do I install Jimsim?
First, make sure that you have Java installed on your computer. You need Java 1.4.2 or better.
You can get Java from java.sun.com. After you have java installed,
download the Jimsim install jar file from the download page.
What do I need to run it?
Java 1.4.2 or greater. You can get it from java.sun.com
It says that I can't start Jimsim, it complains that it can't open sockets 10000, 10001, and 10002. What gives?
Jimsim works by opening up ports on your machine to allow you to telnet to the virtual "routers". The default
ports are 10000, 10001, and 10002. If the ports are unavailable you might see this error:
Exception caught:Address already in use
or
Port already in use, unable to start virtual router
First check that you don't already have an instance of Jimsim running. You can only start one copy of Jimsim
at a time. If that's not the case, something else must be using those ports on your computer. You can change the ports that Jimsim uses.
Edit the file jimsim.props in the Jimsim install directory.
Change the 10000, 10001, and 10002 to something else and retry restarting Jimsim.
What's a jar file?
A method for packaging java programs.
My license expired. I thought this was free software, why is it licensed?
If you redownload the
jar file, you should get a new license. The software is licensed in intervals of 3 months at time. For now,
this is just the way it is.
Update: License has been removed with version 1.1!
Using Jimsim
How do I run it on Windows
If you have Java installed already, you only need to click on the jar file to install
Jimsim. Once installed, just click on the jimsim.jar file inside the installation directory in order to start Jimsim.
If
you can't start it that way, start a command shell (Start->Run->"cmd") and cd to the installation directory. Then run
java -jar jimsim.jar to start jimsim.
Does it run on Linux?
Yep. Start a shell and cd to the installation directory. Then run java -jar jimsim.jar
It should also run on all BSD variants (FreeBSD, NetBSD, and so on.)
How about a Mac?
I have yet to test this. But I'm pretty sure it will work okay.
Will Jimsim interfere with my real network?
No. All the network connections (except for the telnet connection
servers) are totally emulated withing the Jimsim virtual networks. All packets between the routers is 100% emulated and
never goes out your actual computer's network connection.
How do I connect to the virtual routers?
To connect to the virtual routers, use your favorite
telnet program and connect to your local device with the associated port. For the default settings, Router1
is port 10000, so to connect you use telnet localhost 10000. Router2 is port 10001, which is telnet localhost 10001
and so on. If you have trouble starting Jimsim on those ports, you can change the port settings in the
jimsim.props file. If you change these settings, you must use those ports in your telnet program.
When I try to telnet, I get "connection failed" errors
If you try to telnet and you see something
like this:
C:\Documents and Settings>telnet localhost 10000
Connecting To localhost...
Could not open connection to the host, on port 10000:
Connect failed
Either your firewall software is blocking the ports, or you Jimsim application died. If you are running
Windows, check your firewall settings. If you are running Linux, make sure that your iptables or ipchains
settings are allowing the ports. (For example, /etc/sysconfig/iptables).
Another problem might be that you've changed the router ports in the jimsim.props file. If you have done
that, telnet to those ports instead of the default ones.
Features
What router features does Jimsim emulate/support?
For version 1.0, the feature support
list is rather small. You can find an entire list on the About Jimsim page.
What features are coming?
I'm working on some pretty cool new features. See the
About Jimsim page for more information.
How will I know when the next version is released?
Sign up for the newsletter. I promise
not to tell anyone your email address.
When is the next version coming out?
Since I have a day job,
I can't make any promises. I'm hoping to have new versions every two or three months.
This thing is full of bugs! How can I tell you about them?
You can find a bug list page on
our public forums. (See the links to the left.) You can post bugs there. Or, send me an email.
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