With rapid popularization of IPv6 network, network security has become one of the main factors which can impact the development of IPv6 network. DDoS(Distributed Denial of service) attacks are the leading thread to the Internet. In this paper, firstly the security of IPv6 protocol and DDoS attacks are introduced. Then, two main security applications based on IPv6 campus network are introduced. Finally, a test is carried out to see if they are effective to prevent DoS/DDoS attacks. Keywords-IPv6; IPSec(Internet Protocol Security); DDoS/DoS; network security I.specific authentication mechanism designed for certain routing protocol. The network topology is shown in Figure 3. Host A and D connect with CERNET2 through gateway server B and C which deploy IPSec and set up a secure channel, by which communication can be protected from a local subnet to another remote subnet. In fact, the secure channel forms a VPN and two routers run ESP in tunnel mode, thus protect host communication within the network, in which all hosts do not have to configure IPSec. When host A sends packets to Host D, router B encapsulates these packets, and then they pass through the tunnel within the public network CERNET2, and finally arrive at router C which decapsulates these packets and forward them to D. The reverse process is also true.

Multicast technology is widely used in the field of video transmission. Firstly, the working mechanism of the traditional IP multicast and the application-layer multicast is described in the paper, and their advantages and disadvantages are analyzed and compared. And then a new ALM-over-IPM multicast model is proposed, and the working mechanism and key technology of it are analyzed. Finally, Simulation environment is constructed, and a test is carried out to validate the feasibility of the new model.