Analysis of Basic Quality of Service Mechanism for Voice over IP In Hamdard University Network Campus Shahbaz Akhatar Siddiqui Student MS (Telecom) Hamdard University Karachi Junior Lecturer in National University of Computer and Emerging Sciences FAST Karachi Email : shahbaz.siddiqui@nu.edu.pk Abstract One of the fastest growing areas of Communication at the moment is VOIP. VOIP is revolutionizing the world of communications. It allows you to make and receive phone calls over the Internet and IP networks for much cheaper than with the traditional landline phone network. VOIP bring along with his benefits introduce new challenges in the area of communication for the researcher s. The main challenge in this technology is VOIP traffic is extreme sensitivity to delay and packet loss compared with other network applications. In this research paper we propose an infrastructural solution to implement the VOIP service through soft-phone in the interconnected campuses with the help of Network Monitoring tools and basic Qos mechanism. We focus our study in this research paper on quality of voice, packet lose, delay time and jitter Index Terms Delay time, Jitter, Packet Lose Soft-Phone, VOIP I. INTRODUCTION This Era of telecommunication denoted as the fastest growing technological Era. Many developments has been reputed during several research work one of famous development is VOIP. The main challenge is VOIP extreme sensitive to delay and packet lose compared with other network application such as web and email services. VOIP is a well suited solution for network such as LAN that replace relatively expensive and circuit switched based PSTN network The Objective of this study is to suggested a way how efficiently implement VOIP service in the interconnected University campuses through soft-phone to do this First focus is to analyze the interconnected campuses infrastructure and find the existing fault in the present infrastructure network of both campus then implement VOIP service through Soft-phone apply different QOS Method i.e. FIFO, Priority Queuing, Fair Queuing in interconnected campuses interface and suggest the Better one Figure 1 shows Cisco IP Communicator that is used in real network environment for the experiments Figure 1 Cisco IP Communicator Soft-Phone The Demand of this research work was real network environment, according it was decided to research Hamdard university Campus Network Environment Figure 2 Show the Network infrastructure of Hamdard University main and City Campus Figure 2 Hamdard University Network Environment 8
Hamdard University Network Based on Cisco Environment It consist over 500 Nodes in which 5 labs of different Purposes are exist The internet Facility is Provided through Pakistan Educational Research Network (PERN) which is up to 24 MB the Main Campus is connected with City Campus Through Radio Links That links is Provided by another Company that is COMSAT that links is 2MB II. RELATED WORK Regards VOIP as appropriate technology for roaming academics and local deployment for telephony services.[2] VOIP is rapidly growing and becoming a mainstream telecommunication services, not only because of the lower cost compared with the traditional PSTN (Public Switched Telephone Network )but also its convergence Technologies of Data and Voice communication.there have been many studied on VOIP measurement.[3] Markopoulou measured loss and Delay characteristics of American Backboon network and analyzed how these characteristics impact VOIP Quality. [4] Juniper Networks, suggested high-performance network infrastructure that creates a responsive and trusted environment for VOIP services via wired or wireless LAN (WLAN) access points. Access layer switches operate on 100 Mbps Port speed Distribution Layer The distribution layer aggregate the data received from the access layer switches before it is transmitted to the core layer for routing to its final layer. The main Function of the distribution layer in campus environment is to control the flow of network traffic using Access control list and reducing broadcast domain by performing routing function between VLANS.For Example in a campus environment we have a separate traffic according to faculty, student, Voice and staff the uplinks of access layer and the Distribution layer should be on gigabit port or 1000 mbps Core Layer The Core layer of the hierarchical design in the high speed backbone of the internetwork.the core layer is critical for interconnectivity between distribution layer devices.the uplinks of core layer and the Distribution layer should be on Fiber because Fiber works on speed of Lights Figure 5 Show Hierarchical Design of layer Approach Network III. DESING CONSIDERATION OF CAMPUS NETWORK The campus LAN must be implemented Layer approach Network that consist three layer those are Access layer Distribution/aggregation layer Core Layer Figure 4 Shows that all these layer in campus Environments Figure 5 IV. QOS BETWEEN INTERCONNECTED CAMPUS NETWORKS Access Layer Figure 4 The campus access layer provides network connectivity to end users by connecting devices such as PCs, printers, IP Soft phones, and CCTV cameras to the corporate LAN [5] In Networking QOS (Quality of Service) mean a large number of arrays of concept and tools that can be used to effect the network traffic as per the demand. Quality of service is the ability to assign priorities to various application,user or input streams Quality of Service is important if the Network traffic Feel congestion For example in University during Launch Break mostly student utilize this time to surf internet at same time very important voice communication take place between two campuses voice communication feel degradation due to no characterization in the network traffic. During the communication, a packet can be late or not come at all and these problem can be classified as 9
Delay Jitter Packet Lose Delay Actually delay mean receiving packet is so late therefore in voice communication delay play a very vital role there are many type of delay but those delay that play a vital role in this research is Serialization Delay Queuing Delay Compression Delay Network Delay In this research paper I focus on Serialization Delay and Queuing Delay small, typically less the one in one billion. Therefore the larger concern for packet loss is loss due to full buffer and queue V. METHADOLOGY Figure 6 Shows the overall framework of analyzing the campuses Network For efficient implementation of VOIP Serialization Delay Serialization delay define the time it take to encode the bits of a packets on to the physical interface If the Link is Fast, the Bits can be encoded on to the Link more Quickly if the Link is slow it take longer to encode the bits on the links.likewise if the packet is short it does not take as long to put the bits on the link as compared with the Long packet use the following formula to calculate serialization delay for Packet Queuing Delay Bits sents/link Speed Packets experience queuing delay when they must wait for other packets to be sent. Queuing delay consist of the time spent in the Queues inside the Device.The Queuing time can relatively large hundred of millisecond,or may be even more.to reduce the waiting time of Packets we use some mechanism these are Priority Queue FIFO Queue Fair Queue Jitter Figure 6 For Analyzing the campus Network we use Colasoft Capsa.After analyzing the campus network correct those week points that is identify during analyzing implement voice and data vlan Because we assume that campuses have two type of traffic one is voice and the other is data that is further classify as student, faculty and staff vlan Now Implement VOIP in the interconnected campuses and then again re-analysis the network for voice traffic Figure 7 Shows the overall Framework of the VOIP performance analysis in the experiment the performance analysis will focus on jitter Delay packet lose over LAN.VQ manager is used to analyse VOIP traffic in the interconnected campuse Jitter is defined as a variation in the arrival rate of Packets that were transmitted in a Uniform manner Consecutive packets that face different amount of delay have experienced jitter.voice degrade quickly when jitter occur Data application tend to be much more tolerant of jitter Packet Lose The last QoS traffic characteristic is packet loss. Router interface lose/drop/discard for many reason in most network today the number of packet lost due to bit error is Figure 7 10
VI. PROPOSED NETWORK INFRASTRUCTURE IN INTERCONNECTED CAMPUSE ENVIROMENT The Demand of this research work was real network environment, according it was decided to research Hamdard university Campus Network Environment. first we analyze both network on individual basis for indentify the week points in the campus physical network infrastructure with the help of network monitoring tools then implement VOIP service in the interconnected campuses through softphone then again analysis the VOIP service in the interconnected campuses with help of VQNET (VOIP) and implement the Queuing mechanism on the interface of interconnected campuses After full assessment of campus network I find the following week point in the network through which the network performance is week No vlan is implemented Back bone of labs connected through 100 mbps ports No characterization of traffic The campus is interconnected through radio Links Correct those week point implement vlan on both campuses Backbone converted in to Gigabit port. Voice and data Traffic is characterize and the radio links should be change to fiber connection then implement QOS Congestion Control Mechanism and See the Performance on Priority Queue,Custom Based Queue,Fair Queue Figure 8 Shows the proposed infrastructure for main and City Campus VOIP Soft-phones. SCCP defines a simple and easy to use architecture, while the H.323 recommendations are quite an expensive system. In the experiment I follow the Following Condition 2 GB Data is moved during Voice Communication The First Result represent the condition when no vlans is implemented in the campus environment and campus are connected through serial radio links Data Traffic The above result shows that due to radio link interface between interconnected campuses the packet loose, jitter And delay value reaches up to the tolerable value and the data traffic move up and down this is due to the interconnected links between interconnected campus and that is radio link The Second Result Represent the Condition when Only Serial link is changed From radio to Fiber Connection and Vlan is implemented on both campuses FIFO Queuing Mechanism is implemented on both campus interface the out put of the router when FIFO is implemented on the interface are Figure 8 VII. RESEARCH RESULT This section analyzes, measure and compare VOIP performance in the interconnected campuses environment First take a result on existing Network infrastructure we implement VOIP service with the Help of cisco call manager express that is present in 3700 IOS Use Skinny Client Control Protocol (SCCP) that is a Cisco proprietary protocol used between Cisco Call Manager and Cisco Hardware is Lance, address is 0007.ec70.d8db (bia 0007.ec70.d8db) MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set ARP type: ARPA, ARP Timeout 04:00:00, Last input 00:00:08, output 00:00:05, output hang never 11
Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: fifo Output queue :0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec The Fourth Result Represent the Condition when Voice Traffic and data vlan are working on custom Queue in which those Queue that have more packet have higher Priority then the other one Queue-list 101 permit tcp any any eq 2000 Queue-list 1 protocol tcp 1 list 101 Queue-list 1 default 2 Queue-list 1 queue 1 byte-count 3000 Queue-list 1 queue 2 byte count 3000 Data Traffic The Third Result Represent the Condition when Voice Traffic get high Priority and data vlan low Priority this condition is apply with the help of extended access-list in the router interface DATA Traffic Extended Access-list are Access-list 101 permit tcp any any eq 2000 Priority-list 1 protocol ip high list 101 Access-list 102 permit ip any any Priority-list 1 protocol ip medium list 102 Data Traffic VIII. CONCLUSION The purpose of this paper was to investigate which Qos mechanism is the most appropriate for the proposed Network infrastructure of Hamdard University Network environment.the tested QoS mechanism are FIFO, Priority Queuing and Fair Queuing In FIFO Queuing result the delay is always occur and it will be increase when data traffic is more busty when Priority Queue is applied on the interface the voice packet get high priority and data become medium priority the result shows voice packet feel no congestion,packet lose but some jitter in that case the data traffic suffer from delay the Last mechanism of Qos Queuing show relatively better result from the above one that is Custom Based Fair Queuing in which both Voice and data Traffic have equal Priority and none of the traffic feel congestion and packet Lose 12
REFERENCES [1] http://www.cisco.com/en/us/tech/tk652 /tk701/technologies configuration_guide_chapter09186a00800eadf9.h tml [2] Daniel Collins, Carrier Grade Voice over IP, 2nd Ed., McGraw-Hill,September 2002. [3] A. Markopoulou, F. Tobagi, and M. Karam, "Assessment of VoIPquality over Internet backbones", in Proc. of IEEE INFOCOM, NewYork, NY, Jun. 2002. [4] Juniper Networks Campus LAN Design Guide [5] Welndell OdOM,Michael J.Cavanaugh, IP Telephony Self Study Cisco QOS Exam Guide, Edition Second 13