1 Study on Adaptation of CDN Request-Routing to Scalable Conference 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 １． Background ２． Goal and approach ３． Evaluation ４． Consideration ５． Conclusion Contents

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 Host AHost B Host A Host B Host C Host D １． Background － H.323 conference system

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 MCU ← overload 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 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 ２． Goal and approach － Load Sharing by Hosts Obtain scalability for the number of hosts Existing method Proposal method

6 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. ２． Goal and approach － Application Level Multicast Lobby server New host Entry IP address list Make links AS1AS2 Make high cost links between ASs 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 Origin server surrogate client Redirection server contents request select notify Delivery contents

8 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 ２． Goal and approach － Request routing using DNS New host DNS server conference.ac.jp （ host name ） 133.x.x.xxx 133.x.x.xxx （ IP address ） select connect AS 1 AS 3 AS 2

9 ３． Evaluation － Evaluation Environment 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 ※ １～２ ５６ Change distribution of hosts Change the number of active AS –Speakers １～１２８、 Hosts １ ２８ Experimental Network （ SuperSINET ） Simulation based evaluation using network simulator “NS ２ ” ※ Speakers = the number of source hosts, hosts = the number of destination hosts

10 ３． Evaluation － simulation under the 3 distribution of hosts Speakers １, Hosts １～２５ ６ –Distribute hosts to 6 ASs –Measure under the 3 distribution of hosts Concentrate at 1 area Concentrate at 2 areas Concentrate at 3 areas Result –the increase amount of network load is decreasing as the number of participants increase → Scalability to the number of hosts. –ORIO is better than ALM at load sharing Maximum use of bandwidth (kbps) The number of hosts 1 area (ORIO) 2 area (ORIO) 3 area (ORIO) 1 area (ALM) 2 area (ALM) 3 area (ALM)

11 3.Evaluation － Change the number of ASs Speakers1,Hosts １～２５６ –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 Maximum use of bandwidth (kbps)

12 3.Evaluation － Speakers Change the number of Speakers Speakers 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. Maximum use of bandwidth (Mbps) The number of speakers

13 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 ４． Consideration － Efficiency of ORIO and restriction of ALM

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

15 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 ５． Conclusion