Abstract 2.1 Weighted Round-Robin

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1 Weighted Round-Robin DNS FTP Abstract More and more network services needs powerful server to handle. However, quite a lot of services may not be able to handle by a single server. The cluster server system provides fluent services to the large enterprise and business website, which can sustain a large number of connections in a short period of time. However, the cost of cluster server system is quite expensive. In this paper, we propose a system that uses the Weighted Round-Robin algorithm to implement a load balance web server system from a large number of heterogeneous servers, including general purpose personal computers and low end PC servers. We use a number of client computers to simulate the client requests to our load balance server system. The experimental results show that our system not only have the capability to process a large number of connection requests but also successfully distribute the load to individual server according to its capacity. Keywords: Web server, Server load balance Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 280

2 IFM(Intelligent Forwarding Scheme) [3] BCAKEND SERVER SERVER TABLE CLIENT REQUEST INTELLIGENT FORWARDER TABLE Layer 4 ~ Layer 7 BACKEND SERVER ISO CLIENT Client SERVER Session Intelligent Forwarding Scheme ( ) DNS forwarding scheme DNS DNS Zone IP Domain name Front node REQUEST DNS Domain name IP DNS Round-Robin Back node IP [3] DNS forwarding scheme Proposed load forwarding scheme Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 281

$Weighted Round Robin algorithm Capacity = ceil{(cpu idle time)/100) * Capacity_ base} (3.$ 2) Capacity_base CPU Speed ( Unit: Capacity_base MHz) >2400 10 1800 ~ 2400 8 1200 ~ 1800 6 800 ~ 1200 4 600 ~ 800 3 200 ~ 600 2 <200 1 Selector Server IP Database Selector 1 2 Serverlist table Sever

2) Capacity_base CPU Speed ( Unit: Capacity_base MHz) >2400 10 1800 ~ 2400 8 1200 ~ 1800 6 800 ~ 1200 4 600 ~ 800 3 200 ~ 600 2 <200 1 Selector Server IP Database Selector 1 2 Serverlist table Sever

3 Step 1 Client SELECTOR Step 2 SELECTOR Database Serverlist Table IP Step 3 SELECTOR header-redirection Client IP Step 4 Client Step 5 Client Serverlist table Server Capacity Capacity Server Capacity Weighted Round Robin algorithm Capacity = ceil{(cpu idle time)/100) * Capacity_ base} (3.2) Capacity_base CPU Speed ( Unit: Capacity_base MHz) > ~ ~ ~ ~ ~ <200 1 Selector Server IP Database Selector 1 2 Serverlist table Sever IP Sever IP Selector Server IP CPU Capacity CPU CPU CPU Capacity_base Capacity Capacity Serverlist table Server IP Serverlist Serverlist table Selector Round Robin Request Processing Steps Weighted Round Robin 3. Knoppix live-cd Apache MySql Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 282

2 SERVER IP Hardware configuration Number of CPU RAM computer Intel PIII 800 256 MB 4 Mhz AMD Duron 256 MB 4 1200 Mhz Intel P4 1500 256 MB 4 Mhz Intel P4 2400 512 MB 1 Mhz Software configuration

4 2 SERVER IP Hardware configuration Number of CPU RAM computer Intel PIII MB 4 Mhz AMD Duron 256 MB Mhz Intel P MB 4 Mhz Intel P MB 1 Mhz Software configuration Operating System: Knoppix 3.3 LTH-remaster version, Linux kernel Database: MySQL Modify the parameter in my.cnf Disable skip-networking Set max_connections = Set max_connect_errors = Webserver Apache Modify the parameter in httpd.conf MaxClients = 4096 MinSpareServers 5 MaxSpareServers 50 StartServers 20 MaxRequestsPerChild 1000 MaxKeepAliveRequests 0 KeepAliveTimeout 30 Timeout 600 The web server port for the selector is 80 and is 2222 on ther servers and clients. Selector Database 4. Capacity P-III 800 Mhz AMD DURON 1200 Mhz P Selector P Mhz Selector 2 Database system P4 2.4G PIII 800 Serverlist table Request Request CPU utilization P4 1.5 GHz 15 Database Database Capacity Apache Database DATABASE DATABASE Serverlist table Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 283

5 CPU utilization AMD Duron 1.2 GHz CPU utilization P3 800 MHz CPU 101 Selector DATABASE Selector Selector DATABASE 5. Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 284

6 Capacity B [1] Cardellini, V., Colajanni, M., Yu, P.S Dynamic load balancing on Web-server systems Internet Computing, IEEE, Volume: 3, Issue: 3, May-June 1999 Pages: [2] Jiannong Cao, Yudong Sun, Xianbin Wang and Sajal K. Das, Scalable load balancing on distributed web servers using mobile agents, The Hong Kong Polytechnic University, 2003 Elseier Inc., J. Parallel Distrib. Comput. 63 (2003) [3] Paul, A., Wu-Chi Feng; Panda, D.K., Sadayappan, P, Balancing Web server load for adaptable video distribution, Parallel Processing, Proceedings International Workshops on, Aug Pages: [4] PHILIPS S. Yu, VALERIA CARDELLINI, MICHELE COLAJANNI, Dynamic load balancing on web-server systems, University of Rome Tor Vergata, University of Modena, IEEE INTERNET COMPTING,1999 P28-P39, [5] Tsang-Long Pao, Jian-Bo Chen, I-Ching Cheng, An Analysis of Server Load Balance Algorithms for Server Switching, Ming-Chung University 2004 International Academic Conference, pp , Mar [6] Proceedings of the Taiwan Academic Network Conference 2004 (TANet 2004), Oct , 2004, Taitung, Taiwan, page 285

A two-level distributed architecture for Web content adaptation and delivery

A two-level distributed architecture for Web content adaptation and delivery Claudia Canali University of Parma Valeria Cardellini University of Rome Tor vergata Michele Colajanni University of Modena