Comparative Analysis of LLQ Traffic Scheduler to FIFO and CBWFQ on IP Phone-Based Applications (VoIP) Using Opnet (Riverbed)

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1 Comparative Analysis of LLQ Traffic Scheduler to FIFO and CBWFQ on IP Phone-Based Applications (VoIP) Using Opnet (Riverbed) Rizal Broer Bahaweres 1, Ahmad Fauzi 2, Mudrik Alaydrus 3 rizalbroer@ieee.org, ahmad0303.fauzi@gmail.com, mudrikalaydrus@mercubuana.ac.id 1 Department of Electrical Engineering, Mercu Buana University, Jakarta, Indonesia 2 PGII Vocational High School, Bandung, Indonesia Abstract- Nowadays, world is on going to Convergence Era, where data, voice, and video overcome to pass through same network, like IP network. Unfortunately, the fast growth of application technology has not been supported yet by default IP network in the case of quality of service. We have known, that voice over IP services have sensitivity to delay, jitter and latency. And it require of different bandwidth which is also required some service guarantee. How to comparing queue mechanism of VoIP attributed to QoS?. In this case, we need to give guarantee of QoS relied on operation of data packages to be delivered along with its scheduling. Scheduling represent queue mechanism from an applying of network QoS s, that is an arrangement process of an exit and entry of assumed data packages queuing exceed CIR (Committed Information Rate) specified. Regulation of this data exit and entry can be formed with specified classification. This research compare queue method of First In First Out ( FIFO) with two algorithm type of WFQ scheduling which at most used, that is Class Based Weighted Fair Queuing (CBWFQ) and Low Latency Queuing (LLQ). Based on delay, jitter, and MOS (Mean Opinion Score) obtained, LLQ give a better network performance Keyword: VoIP, QoS, CIR, LLQ, Riverbed. I. INTRODUCTION In supporting growth of a sustainable development, a development of friendly environment technology is urgently needed. Technological environmental friendliness earn is also marked with existence of a better technology development giving effectiveness. Among other is development of technology giving the increases of our network performance. Human internet activity is being progressively in time. Taken from survey, obtained at just 2011, the activity in most business sector is often by to send and accept equal to 97.69%, while the lowest percentage activity is hotel promotion equal to 0.03%, teleconference through VoIP its self equal to 13.54% [16]. This percentage is indicate that the requirement of VoIP technology need excellence of good network. With an early hypothesizing that queue mechanism of LLQ have better performance [16], [13], this research conducted to know as for how comparing VoIP queue mechanism to it s QoS? In this case, by comparing traffic scheduler of VoIP with algorithm of Low Latency Queuing (LLQ) with First In First Out ( FIFO) and Class Based Weight Fair Queuing (CBWFQ). As for limitation, this research concern on several things, that network only focused at two router and also in application of VoIP, then this research use simulation software of Riverbed Academic Edition in it s perception. II. THEORY Information for the classification process in the IP header field or in other words the process of classification on layer 3 of the OSI standard, there are two kinds, namely IP Precedence and Differential Service Code Point (DSCP). This classification information specified in the first three or six bits of the field Type of Service (ToS) in the IP packet header. Based on the timeline-based categories, there are 3 Network QoS parameters, namely Delay, Jitter and Response Time [15]. In here, we are only use the Delay and Jitter parameters because these parameters have the greatest influence on the Network. This research are also used mean opinion score (MOS) to analized the performance of network. A. Delay Delay is the time it takes a bit of data to pass through a network from a node to another node. There are three pieces of delay, namely - Transmission Delay - Propagation Delay - Delay processing Performance is considered good if the value of the resulting delay getting smaller. To compute a delay can be formulated as follows: Delay = Time of Arrival - Post time (1) In OPNET tutorial outlined on its website[18], the delay represented by End-to-end delay, ie a total delay of voice packets (analog-to-analog) mathematically written: Packet end-to-end network delay = delay + delay + delay encoding decoding + compression decompression delay + delay + delay dejitter_buffer (2) /15/$ IEEE

2 B. Jitter Jitter is a variation of delay caused by long queues in a data processing time. There are two types of jitter, which is one way jitter and inter-arrival jitter. Mathematically written as follows. total _ time average _ delay = (3) packet _ arrival The ITU-T standard value of jitter is still tolerable is 30 ms. C. Mean Opinion Score (MOS) Mean opinion score ITU Recommendation P.800 is used to measure the performance of a multimedia communications over a network based on a view of the end user. In the multimedia communication network (such as audio, video, or voice telephony), especially when the codec used to compress the bandwidth required for the communication, it takes MOS to measure the extent to which the quality of the communication is based on the perspective of the end user. End users will provide an assessment of the range of numbers 1-5 wherein, figure 1 means very poor quality and number 5 is very good quality. Fig. 2. LLQ Architecture (Implementing Cisco QoS, 2006) III. RESEARCH METHODS The research method used is the application and measurement of simulation network using Opnet/riverbed software. As for the mind set of simulation/research is can be depicted at picture below. D. Traffic Scheduller 1) First In First Out (FIFO) traffic scheduller FIFO queuing technique refers to the FCFS (First Come First Serve), the data packets are processed first come first. Data packets that come out first in the input into the FIFO queue, and then issued in accordance with the order of arrival. FIFO queuing technique is suitable for medium-sized networks with bandwidth of 64kbps but spend enough processor and memory resources. Start Literatur Study above VoIP, queuing method, dan OPNET/Riverbed simulation Network Configuration Initialisation Network topology state Fig. 1. FIFO queue [6] Data Taking Simulation / research duration Simulation Scenario state 2) Weighted Fair Queuing (WFQ) traffic scheduller WFQ consists of two types of algorithms, ie CBWFQ and LLQ as described later. WFQ mathematically expressed by SN (Sequence Number) in the equation: Then, SN = Previous_SN + (Weight * New_Packet_Length) (4) Quantitative Delay: 1. FIFO 2. CBWFQ 3. LLQ Jitter: 1. FIFO 2. CBWFQ 3. LLQ Qualitative MOS (Mean Opinion Score) Weight = 32384/(IP Precedence +1) (5) CBWFQ in initial mode on an interface separates traffic into flows, determining the transmission speed of each queue, and then weighting the priority of each queue. From the perspective of WFQ, there are two categories of data flows: a session high bandwidth and low bandwidth session. Low-bandwidth traffic effectively given priority over high-bandwidth traffic, and high bandwidth traffic transmission service proportionally dividing joint according to a predetermined weighting. No Data Analysis End of Simulation Yes Conclusion End Fig. 3. Research Design

3 Scheme of simulation used to design network system to be used at this research, as well as designing topology for the VoIP nodes. Making of simulation, that is to make simulation in OPNET/Riverbed Academic Edition based to devices which have been made before. The measurement done with measuring performance from three queue method of FIFO, CBWFQ and LLQ at parameter of Packet End to End Delay, Jitter, and Mean Opinion Score ( MOS). Data retrieval is steps to be taken after the results of the measurements obtained. The data obtained from simulations using OPNET/Riverbed Academic Edition. From the results of the processing of this data will be created statistics from the data obtained. Then, do the analysis and drawing conclusions on all results of data retrieval. As for application settings and configurations can be done as option following, pursuant to topology settings and of the following atribute. Profile configuraton in network above is: FTP Profile (Application: Aplikasi FTP, with Start Time Offset : constant (5), and Repeatability: Once at Start Time, Operation Mode: Simultaneous, Start Time: constant (100), duration: end of simulation); Video Profile (Application: Aplikasi Video, with Start Time Offset: constant (5), and Repeatability: Once at Start Time, Operation Mode: Simultaneous, Start Time : constant (100), duration: end of simulation); Voice/VoIP Profile (Application : Aplikasi Voice, with Start Time Offset: constant (5), and Repeatability: Once at Start Time., Operation Mode: Simultaneous, Start Time: constant (100), duration: end of simulation). IV. RESEARCH RESULTS A. Voice Traffic Average FIFO, CBWFQ, and LLQ Voice Traffic Sent to be obtained from FIFO, CBWFQ, and LLQ in the measurement have same values. This means that all of the method of queuing is observed, ie FIFO, CBWFQ and LLQ, experiencing the same conditions. Fig. 4. Network Topology [9] Network topology above consist of: 4 workstation 10BaseT, link 10BaseT, 2 Router, FTP Server, Video Server, and PPP DS1 link with capacities of link 1,544 Mbps with average packet size 200 byte. That workstations is: FTP Client is conduct transmission of FTP with FTP Server, by 50% command put and 50% command get, inter request time generated with constant distribution, and mean outcome is 10, file size 500 kbps. With Type of Service: Best Effort. Video client, by default consist of 1 user asking for video service of video server Voice over IP - VoIP 1, to get communications voice with VoIP 2. Voice over IP - VoIP 2, to get communications voice with VoIP 1. In the network there are 3 applications: FTP Application (Parameter for the application of this FTP is: High Load with Type of Service (ToS) is Best Effort (0)); Video of Application (Parameter for the video application is: VCR Quality Video, with ToS Streaming Multimedia (4)); Voice Application (Parameter for the application of this FTP is: PCM Quality Speech, with ToS Interactive Voice (6)). Fig. 5. Average in Voice Traffic Sent of FIFO, CBWFQ, and LLQ Fig. 6. Average in Voice Traffic Received of FIFO, CBWFQ, dan LLQ

4 By this data, we obtained that Voice Traffic Received to be obtained from result is that maximum number reach 3,105kbps. Then, Voice traffic received to be obtained from result that maximum number reach 3,741.4kbps, and Voice traffic received to be obtained from result is that maximum number reach 3,741.7kbps. B. Voice Packet End-to-End Delay of FIFO, CBWFQ, LLQ From the above results, it can be concluded that the result of the jitter value obtained is within the limits of the ITU-T standard value of jitter is still tolerable is 30 ms. The graph also shows that for every scenario jiiter greatest value obtained in the FIFO scenario, this is due to the instability of the network delay when using the FIFO than CBWFQ and LLQ. So, Higher jiiter values to be got at FIFO scenario, this matter because of instability of delay when using FIFO compared to CBWFQ and LLQ. D. Mean Opinion Score (MOS) of FIFO, CBWFQ, and LLQ Fig. 7. Voice Packet End-to-End Delay of FIFO, CBWFQ and LLQ At FIFO, delay happened until number 2s, while CBWFQ and LLQ delay at spanning 0,01s. LLQ data and CBWFQ relatively have same value, some this LLQ data below CBWFQ is equal to 105ms. But some other CBWFQ delay data doesn t. It s means that this LLQ can degrade delay compared to CBWFQ but relative unstable yet. At some data, LLQ have smaller delay than CBWFQ, that is about 105ms. Both queue method, that is CBWFQ and LLQ, have value of delay below 150ms. Its mean can be well accepted by user. This matter refers to recommendation of ITU-T G.114 concerning delay at one way communication. The application network delay of VoIP, including best range ms (acceptable for most application). C. Jitter of FIFO, CBWFQ, and LLQ Fig. 9. MOS of FIFO, CBWFQ and LLQ By refers to ITU-T P.800 recommendation, from result of average value of MOS for CBWFQ obtained value 4. While at LLQ obtained by value at 4 also. Differ from FIFO at value 1. Thereby, CBWFQ and LLQ have Good in opinion, while FIFO have very bad in opinion. Related research conducted by Miftah Rahman [16]. In this study, Miftah Rahman analyzed the network quality in the network that integrates VoIP by comparing various kinds of encoding such as G.711 and G.729. Any study found that the congestion management method LLQ produce better delay (time delay is more stable) than CBFWQ method. It is based on Priority Queuing features adopted by the LLQ. Related to this research, analysis of network quality in the network that integrates VoIP, based on parameters of delay, jitter, and MOS, obtained that some of the LLQ voice data congestion management method transfer quality produce better, characterized by a time delay which is smaller than the CBFWQ method. Then, in the qualitative parameters, MOS (Mean Opinion Score) of LLQ and CBWFQ at better than FIFO V. CONCLUSIONS Fig. 8. Voice Packet End-to-End Delay of FIFO, CBWFQ and LLQ The conclusion of this research is Quality of Service condition can be better using LLQ scheduling technique. And for the voice application which is sensitive to delay can still fulfill voice delay standard even network in a overload state.

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