ENTERPRISE NETWORK ANALYSIS: A CASE STUDY OF THE KUWAIT CIVIL SERVICE COMMISSION COMPUTER NETWORK

Transcription

1 ENTERPRISE NETWORK ANALYSIS: A CASE STUDY OF THE KUWAIT CIVIL SERVICE COMMISSION COMPUTER NETWORK Abdullah Kh. Alnusef Dr.Muhanned Alfarras Eng.nusif@gmail.com; dr.muhanned@gulfuniversity.net ABSTRACT The Kuwait Civil Service Commission (KCSC) built an enterprise to allow clients to access those systems. This network covers two buildings: Headquarters (HQ) and Disaster Recovery (DR). In addition, the KCSC network covers more than 250 sites, including all ministries and other governmental agencies. This analysis studies the Local Network Area (LAN) for KCSC using OPNET. The following network parameters are investigated in order to identify any network performance issues: network delay, throughput, packet drops, and jitter. The main results of this analysis show an average network delay of 0.2 ms without any packet drops and a maximum network traffic of not more than 2.2 Gbps, indicating that there is no congestion. Some network jitter appears, affecting VOIP service. The most critical design issue in the KCSC LAN is a lack of redundancy links between core switches and server farm switches, which have very little effect on the redundancy of the network. KEYWORDS OPNET, KCSC, VOIP, QoS, Packet Drops. 1 INTRODUCTION The Kuwait Civil Service Commission (KCSC) plays a critical role in managing human resources operations for the civil sector of the Kuwaiti government. For this role, KCSC has built custom-made, high-end enterprise electronic systems to automate its operations. An enterprise network was established in order to operate these systems, which extend across two building belonging to KCSC and cover more than 250 remote sites including ministries, organizations, and banks. This analysis covers the Local Network Area (LAN) for KCSC in both buildings: Headquarters (HQ) and Disaster Recovery (DR). Using the most reliable network simulator tool (OPNET), the KCSC network was modeled according to the device types in operation and the behavior of the traffic passing through this network. Network parameters were chosen for a simulation in order to identify any hidden performance issues. In addition, network design issues were identified that could affect the availability of the KCSC network. The simulation results were compared with the real values gathered from the KCSC s network monitoring system (Orion Solarwinds) in order to validate the reality of the simulation results. The most important result that can be gathered from this study is the ability to detect some design issues in the KCSC network that directly affect the network s availability and redundancy levels. Also, some voice performance issues were detected using the simulation platform. Finally, technical recommendations were suggested that could enhance the performance and availability levels of the KCSC network s resources in order to serve as a mission-critical system at all times. 2 KCSC NETWORK ARCHITECTURE The KCSC network can be divided into two parts: LAN and Wide Area Network (WAN). Figure 1 shows the high-level design of the KCSC network and the three main WAN providers of the KCSC: 1- Kuwait Information Network (KIN): A governmental private network links most governmental agencies in Kuwait [1]. 2- Wireless Network Providers are responsible for linking 327

2 governmental ministries and other entities. 3- Internet Service Providers. In this analysis, the WAN part and end users outside the KCSC LAN will not be considered. The KCSC LAN can be divided into the following layers: 1- Core switching and routing 2- Server farms switching and routing 3- Edge switching and routing 4- Access switching 5- Wireless Access Points Figure 2 summarizes the layers described above and shows that the core switching layer is the backbone of the KCSC network. Edge and server farm switches are linked with the core switching layer with redundant 10Gbps fiber links. Figure 3 shows the core switching layer, which includes two Cisco 6500-series switches at the main site and one Cisco series switch at the DR site. Edge switches are located in each floor in the main building, and those switches are redundantly linked with each core switch with 10Gbps fiber links worked in Active-Active Mode (i.e., Cisco Global Load Balancing Protocol GLBP). Server farm switches in the main building are linked without any redundancy meaning that each switch is linked to one core switch. The bandwidth at both links is 10Gbps. At the DR site, servers are linked with multiple cascaded switches with 2Gbps bandwidth for each core switch. Figure 4 summarizes the server farm switching layer [2]. Servers and clients have multiple connectivity options, as shown in Table 1. Table 1. Node connectivity options Role Number of Links Bandwidth End users 1 1 Gbps Test and Dev. Servers 1 1 Gbps Redundancy 2 1 Gbps or Required Servers Throughput Required Servers (Active/Passi ve) 2 (Active/Acti ve) 10 Gbps 2 Gbps or 20 Gbps 3 SERVICES RUNNING ON THE KCSC NETWORK Multiple services run on the KCSC network. Table 2 lists those with the highest traffic[3]. Table 2. Services running on the KCSC network Service Name Integrated Systems for Civil Services Document Archiving System KCSC Microsoft Active Directory IP Telephony System File Sharing Service Role Human Resources and Payroll for Civil Sector in Kuwait Stores KCSC documents; used for paperless organization project KCSC formal service KCSC main authentication and security provider KCSC main internal communication systems User profiles and file roaming 4 NETWORK MODELING AND SIMULATING Number of Servers 4 databases 12 application servers 10 web servers 2 databases 6 application and web servers 1 database 1 Simple Mail Transport Protocol (SMTP) server 1 web server 6 servers 7 servers 6 servers Network modeling is one of the methods used to study the computer network to compare the impacts of various technology designs on the network s end-to-end behavior [4]. Enterprises, organizations, and companies around the world try to achieve highperformance networks by redesigning them periodically. A network model is a description of observed behavior, simplified by ignoring certain details of the computer network. Modeling allows complex networks to be 328

3 understood, and their behavior is predicted within the scope of the model. Generally, in order to evaluate any problem, a logical workflow must be followed [5]. This workflow has five steps: 1- Define the problem 2- Build the model 3- Execute the simulation 4- Analyze the results 5- Make decisions The steps above are summarized in the workflow shown in Figure 5. In this analysis, OPNET Modeler version 14.1 is used to simulate KCSC network and services. 4.1 Investigated Network Parameters In this study, the following network parameters are considered: 1- Network Delay: The time taken for a bit of data to travel across the network from one node to another. Network delay is measured in seconds. This parameter can affect network performance because some network protocols are very sensitive to high delay time, such as VOIP. There are multiple sources of network delay [6], and two are as follows: IP network delay: Delay resulting from packets and bits processing within the network devices [7]. End system delay: Time taken by the service to generate the network traffic and to prepare it for transmission over the network [8]. This parameter has been chosen due to its effect on the services running in the network, such as VOIP or file services [7]. 2- Throughput: Throughput for a onesecond interval is the sum of the total number of bits of all recorded frames transmitted [9]. 3- Packet Drops: Traffic sent and received is measured in bytes between the source and the destination. This parameter helps identify any losses in packets or traffic. Packet drops affect the service and force packet to be retransmitted in the case of TCP or lost in UDP [9]. 4- Jitter: Jitter, measured in seconds, can be defined as variations in the delay of received packets. Jitter primarily affects VOIP services by introducing vocal echoes [10]. 4.2 Simulation in OPNET OPNET provides the ability to take into consideration the physical location and dimensions of the simulated environment [9]. Table 3 shows the KCSC buildings physical dimensions. Table 3. Physical measurements of KCSC buildings Location Parameter Value Coordinates Lat: Lon: Number of floors 8+1 basement Floor area 2500sqm / floor Distance between 3.5 m Main Building floors Distance between 7.5 m (Shuwaikh) edge switch room core cable duct Average distance between end-user devices and edge switch 20 m Coordinates Lat: Lon: DR Building (Sharq Tower) Number of floors 3 Floor area 2000 sqm / floor Distance between 5 m floors Average distance 10 m between end-user devices and edge switch Each building and floor in the simulation has been represented as a subnet (red circle), as shown in Figure 6. Main and DR Building are shown in figures 7 and 8. Floor subnets are presented with three components, as shown in Figure 9: 329

4 1- Edge switch, which links the subnet to the core switching layer. 2- VOIP devices. 3- Personal computers (PCs). The total number of devices is shown in Table 4. Table 4. Total number of network-connected devices in KCSC buildings Building Device Type Total Main PCs 1144 Building VOIP Devices 1210 DR Building PCs 155 VOIP Devices 97 Servers are connected to server farm switches and presented in Figure Applications and Profiles Definitions In order to generate traffic in an OPNET simulation, applications and profile components need to be placed to define the application characteristics, and then traffic is generated from sources to destinations [11]. Table 5 shows the application profiles in the KCSC network simulator. Table 5. KCSC Applications definitions on OPNET Application profile CSC_IS Application parameter Database Browsing Value Heavy load Heavy load CSC_Filenet Database MID Load CSC_EMAI L Browsing Image browsing Mid load CSC_AD Custom NTLM CSC_VOIP VOIP IP Telephony CSC_IPTV Video VCR conferencing Quality Note In real life, more than 2 million transacti ons per day More than 5000 simultane ous users Average of 600,000 transacti ons per day Average of 300 message s per min CSC_Intern et Http video Searching 5 SIMULATION RESULTS Simulation results in OPNET can be measured globally across the simulated environment or by nodes like servers or PCs. According to the investigated network parameters, the following results were gathered. 5.1 Network Delay and Packet Drops Results The average in delay in the KCSC network is 0.2 ms. Figure 11 shows an average global delay graph. Delay was measured on each server in order to evaluate hidden delay issues. Table 6 shows end-point delay results. Table 6. KCSC network endpoint latency measurements in OPNET End point Latency (ms) Cisco call manager server 0.4 Integrated systems DBs 0.9 Integrated systems APP 1.2 Integrated systems WEB 0.6 system 1.2 NAS storages 1.9 FileNET APP 1.3 FileNET DB 0.8 File servers 0.9 PC on Floor PC on Floor PC in Old DR Building 1.0 IP Phone on Floor Average 1.0 Simulation shows that there are no packet drops at all. 5.2 Traffic Throughput In order to identify congestion in the KCSC network, throughput has been measured from the core switches through which all traffic passes. The maximum throughput is 2.2 Gbps. 5.3 Voice Jitter Voice jitter results are shown in figure 12. The x-axis represents the simulation time, 330

5 and y-axis represents the jitter in ms. The average jitter in the KCSC network is 8 ms. 6 KCSC NETWORK ENHANCEMENTS QoS can be achieved by prioritizing traffic [13] to alleviate the latency on the network as much as possible (fixed latency equals zero jitter value). With QoS, voice traffic can be given a higher priority than other traffic. This will minimize the processing time inside the switches and routers between sources and destinations. QoS has been applied in OPNET, and voice packet priority has been set. After applying QoS jitter almost become Zero. Figure 13 shows that result. The KCSC server farm switches have a single supervisor engine. Therefore, multiple supervisor engines on each switch need to be configured to solve the problem. Furthermore, redundant uplinks between each server farm switch and each core switch need to be used instead of a single uplink. All KCSC servers should have a redundant connection between the two server farm switches. Finally, redundant core switches need to be considered at the DR site, and the secondary link bandwidth should be upgraded to 10 Gbps to match the main link to avoid any bottlenecks. 7 CONCLUSIONS KCSC has a robust network infrastructure, which can help to achieve high performance levels. The drawbacks in the current architecture are on availability levels. This analysis summarizes the KCSC network and mentions the procedures followed to build models in the network simulator (OPNET). A thorough analysis is performed on two factors: performance and design. The performance analysis focuses on latency, which clearly affects some network applications. In addition, network throughput is considered to identify any congestion or bottlenecks. On the other side, the study takes a look at the design viewpoint to identify issues impacting the availability levels of the network to meet the business requirements of the KCSC. From the study, the following can be concluded: 1. There is no congestion at all in KCSC s network. 2. The average latency is within limits. 3. From the design aspects, KCSC needs to create redundancy between core-switching layers and server farm switching layers. 8 REFERENCES In order to solve the jitter problem, a technique called Quality of Service (QoS) can be used. This approach allows for the transport of traffic with special requirements. When computer networks are used to deliver voice services, some factors could interrupt this service, such as echo, delay, or crosstalks. 1. Central Agency of Information Technology Kuwait, Projects/Kuwait-Information-Network.aspx 2. KCSC IT Sector, Local Area Network Documentation, KCSC s Internal Documentation, pp , (2010) 3. KCSC IT Sector, Services and infrastructure running inside Data Center, KCSC s Internal Documentation, pp Weilong, Hu, A co-design modeling approach for computer network systems. Simulation Conference, Winter, pp , (2007). 5. Chang, X, NETWORK SIMULATIONS WITH OPNET. Proceedings of the Winter Simulation Conference, pp (1999) 6. Telchemy Inc.. Impact of delay. VoIP performance Management, (2006). 7. Bulira, Damian, Voice and video streaming in wireless computer networks: evaluation of network delays. Future Internet Communications (BCFIC), nd Baltic Congress, pp , (2012). 8. Fall, Kevin, A delay-tolerant network architecture for challenged Internets, Proceedings of the 2003 conference on Applications, technologies, architectures, and protocols for computer communications, pp , (2003). 331

6 9. Jardosh, A. P, Understaning Congestion in IEEE b Wireless Networks. Internet Measurment Conference, pp , (2005). 10. Zheng, L. Characteristics of network delay and delay jitter and its effect on Voice over IP. Singapore: Nanyang Technological University, (2001). 11. OPNET Modeler Manual Online Version, g_with_opnet/textbooks_and_materials/materials/ OPNET_Modeler_Manual.pdf 12. Paganelli, A., QoS performance evaluation of multimedia services in emergency networks, Wireless Communications and Mobile Computing Conference (IWCMC), th International, pp ,(2012). 13. Bolletta, P., Monitoring of the user Quality of Service: Network architecture for measurements, role of the user operating system with consequences for optical accesses. Optical Network Design and Modeling (ONDM), 15th International Conference, pp.1-5, (2011) 332

7 Figure1. KCSC Network High Level Design Figure 2. High-level Design of KCSC LAN Figure 3. KCSC Core Switching Layer Figure 4. Server Farms Switching Layer Figure 5.General Modeling Workflow Figure 6. Top View from OPNET(R) Modeler for KCSC s Main and DR Sites 333

8 Figure7. Main Building s Main Topology in OPNET Figure8.KCSC DR Building Topology in OPNET(R) Figure 9. KCSC Floor Topology Figure 10. KCSC Server Modulation in OPNET(R) Figure12. Voice Performance Parameters from OPNET(R) Figure 11. Global Network Delay in OPNET Figure13. Jitter after Applying QoS 334