Cisco Packet Tracer is a software in which you can simulate the complete network by adding and connecting different network devices. Cisco Packet Tracer is a competitor to the open source GNS3 and Bosan NetSim.
The biggest advantage of Cisco Packet Tracer over its competitors is that it has been released by Cisco. It is not free and is only available for students and instructors who have attended Cisco Networking Academy.
Features of Cisco Packet Tracer 6.2
Some of the features are Cisco Packet Tracer 6.2 are listed below:
Useful for CCNA and CCNP self training
http server adds JS and CSS support, HTTP and FTP linked file management support
Now you can import external file inside Packet Tracer http server
New devices with wlan access point capability and 3G/4G connectivity have been added
Wired sniffer with repeater functionality has been added.
Bugs of Version 6.2
There are a few known ASA 5505 firewall bugs but they should not be a major concern. These bugs only affect ipsec configuration. If you are concerned then you should be looking for Cisco Packet Tracer 7 which is also under way of stable release very soon.