Transcript ppt
Impact Analysis of Cheating in Application Level Multicast s１０９０１７６ Masayuki Higuchi Purpose • Application level multicast is efficient communication technology, and it is used in peer-to-peer service, but they have problems. • To evaluate performance of ApplicationLevel Multicast. IP multicast • Consist of multicast routers, and the router control packets, but all router must be multicast router, so infrastructure building is difficult. • It is unreliable because of the best-effort communication by IP layer. packet Application Level multicast • A technique whereby hosts or end-nodes are organized into an overlay distribution tree without requiring any specific support from the network. overlay network physical network HBM protocol RP • A Host Based Multicast protocol • Control of a single host, the rendezvous point (RP) or controller. • Periodically, each group member measures its distance to others. • The RP is then responsible for the overlay topology calculation and its dissemination among the group members. new member P2P streaming service • Sharecast Without high performance server. User’s nodes relay streaming data • How to connect. Send IP address, MAC address, and channel ID, and version to administrator. Response access point. Reason of Cheating delay; 7sec How to cheat • Always reports a distance of 5 to the source. • Adds 10 seconds to the RTT distances it measured to any other group member. Also, delays by 10 seconds any measurement probes if receives from any other group member. root 5 +10 cheat-node Performance measures for Application level multicast • The link stress Defined as the number of redundant copies of a data packet on the network link. • The relative delay penalty (RDP) Defined as the ratio *TD/*UD. *TD is the tree delay. *UD is the unicast delay. UD TD Impact of cheating in worst case 3 3 cheat-node 2 2 2 2 3 cheating 2 2 3 The link stress: 1 The maximum RDP: 14/2 The link stress: 5 The maximum RDP: 2/2 Impact of cheating in general cheat-node 3 3 cheating 5 The link stress: 3 The maximum RDP: 9/7 The link stress: 6 The maximum RDP: 11/7 Countermeasures against Cheating • Users receives the data from two or more nodes. As a result the influence of the switch of the connection can be decreased. • To detect the cheating, transmit ping to the router that connect one hop short of the cheat-node, and compare with RTT that cheat-node returned. cheat-node real value cheated value Conclusion and Future Works • The countermeasures is effective measures in theory. As a future work, through simulations, confirm the effectiveness of them.