Study on Adaptation of CDN Request-Routing to Scalable Conference System

1. Study on Adaptation of CDN Request-Routing to ScalableConference System Toshiyuki KAWASAKI*Koji OKAMURA** * Graduate School of Information Science and Electrical Engineering (ISEE), Kyushu University ** Computing and Communications Center, Kyushu University Aug 28,2003

2. Contents １．Background ２．Goal and approach ３．Evaluation ４．Consideration ５．Conclusion

3. H.323 conference system is popular • Remote conference • Remote medical care • Remote education • H.323 • Standard of video conference on IP networks • MCU（Multipoint Control Unit） • Enable multipoint conference • Mixing the video and audio streams １．Background－H.323 conference system Host A Host B Host B Host A Host C Host D

4. 1．Background－Overload of MCU • Problem of H.323 multipoint conference system When hosts (participants) increase・・・ MCU may become overload →load sharing is needed ←overload MCU • Existing method of load sharing • Distribute the load to several MCUs When more hosts increase →MCUs may become overload after all Lack of scalability for the number of hosts ←overload

5. ２． Goal and approach－Load Sharing by Hosts Proposal method • Don’t use any MCUs • Hosts connect with each other • Hosts play a role of MCUs • Hosts distribute load • increase of hosts　　　 　→increase of MCUs Existing method Obtain scalability for the number of hosts Proposal method

6. ２． Goal and approach－ Application Level Multicast • Problem of the multipoint conference system without MCU • Each host should select the host which it connects with. • Existing method • ALM ( Application Level Multicast) • Multicast on logical network (overlay network) • Hosts play the role of multicast router on logical network. Lobby server Make links Make high cost links between ASs Entry IP address list New host AS2 AS1 Overlay network

7. ２．Goal and approach－ ORIO and CDN Request Routing • Proposal method ORIO（Optimal Routing Inter Organization） • Using CDN Request-Routing • CDN（Content Delivery Network） • Network of severs to distribute content efficiently • Load sharing by using many surrogates • Request Routing • Select the optimal surrogate for the clients • Tell clients their optimal surrogates contents select notify Redirection server Origin server notify surrogate surrogate Delivery contents surrogate request surrogate client client client client client client

8. ２． Goal and approach－Request routing using DNS • Process of participation at ORIO • Request Routing using DNS • Prepare DNS to redirect requests. • New participants write the certain host name for participation into the packets destination address. • DNS tell the optimal hosts IP address at name resolution. 　→Connected with its optimal host automatically AS 3 DNS server AS 1 select 133.x.x.xxx conference.ac.jp（host name） connect 133.x.x.xxx（IP address） New host AS 2

9. ３．Evaluation－Evaluation Environment Simulation based evaluation using network simulator “NS２” • Evaluation standard • Maximum network load • Comparing with the method using ALM • Experimental Network • SuperSINET • The number of ASs is １８ • The number of hosts per ASs is 64 • Environment • Speakers※　１、Hosts※１～２５６ • Change distribution of hosts • Change the number of active AS • Speakers　１～１２８、Hosts１２８ Experimental Network（SuperSINET） ※Speakers = the number of source hosts, hosts = the number of destination hosts

10. ３．Evaluation－simulation under the 3 distribution of hosts Maximum use of bandwidth (kbps) • Speakers １, Hosts １～２５６ • Distribute hosts to 6 ASs • Measure under the 3 distribution of hosts • Concentrate at 1 area • Concentrate at 2 areas • Concentrate at 3 areas 1 area (ORIO) 2 area (ORIO) 3 area (ORIO) 1 area (ALM) 2 area (ALM) 3 area (ALM) • Result • the increase amount of networkload is decreasing as the number of participants increase 　　→ Scalability to the number of hosts. • ORIO is better than ALM at load sharing The number of hosts

11. 3.Evaluation － Change the number of ASs Maximum use of bandwidth (kbps) • Speakers1,Hosts１～２５６ • Changing the number of ASs which hosts belong to • Select hosts from 6 ASs • Select hosts from 12 ASs • Select hosts from 18 ASs • Result • ORIO is better than ALM at load sharing • ORIO’s efficiency of load sharing become worse when the number of AS is small ( hosts per AS is big). 　　→　Policy of routing within AS should be improved. The number of hosts

12. 3.Evaluation － Speakers Maximum use of bandwidth (Mbps) • Change the number of SpeakersSpeakers １～１２８　　　　Hosts １２８ • Select hosts randomly • Result • Network load increase linearly at both ORIO and ALM. 　→Don’t provide scalability in this case. The number of speakers should be limited. The number of speakers

13. ４．Consideration－Efficiency of ORIO and restriction of ALM • ORIO provide more efficient load sharing than ALM • Possible reason ・ ALM uses logical network for routing, but ORIO doesn’t use it. In ALM, there are two restrictions in receiving streams • Receivable only from its neighbors on the overlay network • Receivable only from its upstream hosts

14. ４．Consideration－restriction of ALM • Receivable only from its neighbors on the overlay network • Receivable only from its upstream hosts → Promote the concentration of the load Concentrate the load Concentrate the load Concentrate the load Concentrate the load speaker Speaker speaker Speaker Host C Host C Host C Host C delay 9ms delay 9ms delay 5ms delay 5ms delay 7ms delay 7ms router Router Router router Can’t use this link though it is useful Can’t use this link though it is useful delay 10ms delay 7ms delay 7ms delay 10ms Not neighbor B is not A’s upstream host (B’s delay is bigger than A) Host A Host A Host B Host B Host A Host A Host B Host B

15. ５．Conclusion • Existing multipoint conference system • MCU easily become overload • Method of load sharing • Any MCU is not used • Hosts play a role of MCUs instead • The system which tells the hosts their connection partner is required • CDN Request-Routing • Result • Prove the scalability of ORIO • Future work • Adding the function which support the hosts exiting process • Improve the policy of routing within AS