Video about using GNS3 simulation for CCNA labs. This video introduce how to install GNS3 anh config it to run effectivelly. It also contains some example labs for tutorial purpose.

GNS3是一个网络模拟系统, 可用于设计极复杂的网络架构, 可让你设定模拟的工作站和路由器.-GNS3 is a graphical network simulator that allows you to design complex network topologies. You may run simulations or configure devices ranging from simple workstations to powerful Cisco routers.

强大的思科路由器模拟软件GNS3的源代码-the source code of gns3

Good for network simulation with CISCO IOS