Cisco Packet Tracer 是学习Cisco 用的模拟器，或者说是一个功能强大的网络仿真程序，目前最新的版本是 Packet Tracer 6.2。

在6.2版本里思科添加了几款新的router 路由器，支持ASA防火墙（ASA 5505） 、ipv6等新的功能。

Cisco Packet Tracer 是由Cisco公司发布的一个辅助学习工具，为学习思科网络课程的初学者去设计、配置、排除网络故障提供了网络模拟环境。用户可以在软件的图形用户界面上直接使用拖曳方法建立网络拓扑，并可提供数据包在网络中行进的详细处理过程，观察网络实时运行情况。可以学习IOS的配置、锻炼故障排查能力。

Packet Tracer在课堂上允许学生用几乎无限数量的设备来创建网络，鼓励网络实践和故障排除。

原文：

Cisco Packet Tracer is a powerful network simulator that can be utilized in training for CCNA TM and CCNP TM certification exam by allowing students to create networks with an almost unlimited number of devices and to experience troubleshooting without having to buy real CiscoTM routers or switches.

Cisco Packet Tracer features an array of simulated Application layer protocols (HTTP, DNS, …), as well as basic routing with RIP, OSPF, and EIGRP, to the extent required by the current CCNA TM curriculum. It also includes Cisco IOS 15 with licence features which was introduced in the CCNA exam in 2013.

Cisco Packet Tracer 6.2 has been released in two versions by Cisco in February 2015 : "Cisco Packet Tracer Student" and "Cisco Packet Tracer Instructor". Cisco Packet Tracer 6.2 includes an ASA 5505 firewall with command line configuration (but no Adaptive Security Device Manageror CCP tools). It also includes a netflow collector as a Desktop application in the server device, routing protocols for IPv6 (OSPFv3, EIGRPv6 , RIPNg), DHCP snooping commands, IPv6 CEF, IPSEC ...

来源：
http://www.packettracernetwork.com/