LiSA , short for Linux Switching Appliance, is an open-source software project built for the GNU/Linux operating system that aims to provide its users with all the necessary instruments for implementing and maintaining an e ficient and reliable switching solution at a low cost.

The project was designed to be used in medium and small-sized networks. As opposed to usual hardware-driven implementations, LiSA offers a software approach to switching by utilizing the Linux Kernel networking stack and adding its own switch-speci c functionality.

Since LiSA is practically a software implementation of what normally is a hardware-based logic, it might seem that there is no advantage in using it. On the contrary, LiSA provides several bene ts that hardware implementations do not have.

Many of these advantages stem from the fact that it is based on the Linux operating system.
First of all this means it is not tied to a speci c hardware architecture. It is only limited to the architectures supported by Linux, of which we mention : ARM, x86, MIPS, PowerPC and many more2.
Secondly, it is not dependant on the network hardware. As long as there is a Linux device driver for the speci c NIC which LiSA is supposed to handle, no problems will be encountered.
Finally, Linux is well-known for its ability to run well on older systems and on embedded devices, that is, devices that have important resource constraints. This provides an advantage since one of LiSA's main objectives is to run on such devices.

The project will not compete with Cisco (we could not do that anyway ) but should provide a cost-effective advanced-featured solution for small networks.

LISA can perform both L2 and L3 switching and configuration is similar to Cisco IOS.
The LISA Project page:
http://lisa.mindbit.ro/

This is a Centos linux with LISA preinstalled Qemu Image.
Download Links:

http://rapidshare.com/files/412464772/lisa-centos-2.0.2.part01.rar.html
http://rapidshare.com/files/412464773/lisa-centos-2.0.2.part02.rar.html
http://rapidshare.com/files/412464774/lisa-centos-2.0.2.part03.rar.html

Configure in Qemu host settings in GNS3
Qemu Image: set path to lisa-centos.img

RAM: 256 MB

NIC: rtl8139

Networking
Place Qemu host icon on GNS3 desktop and start it. Right click on Qemu Host and select Console.
Login to Centos with root account.

Login/password: root/password

To get console of switch just type command "swcli"

Configuration is Cisco like so you shouldn't have problem to setup Vlans, trunks, access ports etc.
Compare to real Cisco switch you need to define ethernet interfaces in config mode of swcli

S(config)# interface Ethernet 0
S(config-if)#exit

After that you should see Ethernet 0 in running-config. Do it for all interfaces you use for switching.

Thanks to brezular@gns3.net
Original post can be found @ http://www.gns3.net/phpBB/topic2403.html

Happy Learning :)