International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 6, June 2015

Performance Analysis of MPLS over VOIP 1

2

Jyoti Aggarwal Akansha Dhall

M-Tech Student1, Assit. Prof. 2 & Department of ECE & Shri Ram College of Engg. & Mgmt Palwal, Haryana, India

Abstract— The recent developments of IP networks are viewing IP applications getting more complicated and requiring more bandwidth consumption. More lately, IP networks are using MPLS, a technique that can be utilized to enhance the IP networks performance. By employing MPLS, data packets can be propagated based on labels instead of destination address. MPLS supports various features like QoS, traffic engineering (TE) and VPNs (Virtual Private networks) etc. The primary feature of MPLS is its Traffic Engineering (TE), which makes a vital part for decreasing the congestion by effective management and load balancing of the network resources. Because of less network delay, effective forwarding mechanism, scalability, improving the speed of packet transmission and determinable performance of the services given by MPLS technology builds it more suitable for carrying out real-time applications i.e. video Conferencing and VoIP. This paper measured the performance matrices i.e. delay, delay variation, throughput, page response time and packet loss for various kinds of traffic (voice, data, video) in their motion in a congested network for both conventional IP network and MPLS-TE. For simulating the both networks OPNET modeler is used. In this paper, the simulation study is carried out to clarify the advantages of employing MPLS-TE for multimedia applications Keywords: MPLS, VoIP, TE, MPLS-TE, IP, OPNET.

I.

INTRODUCTION

traffic performance by simulation between both MPLS and non-MPLS. In this paper, we design a network model by using OPNET simulator for comparison of Video Conferencing and VoIP traffic performance in addition to general data FTP(File Transfer Protocol) on both MPLS and non-MPLS networks. II. TRADITIONAL IP ROUTING The main purpose of IP is to deliver the data from the source node to destination node. Data is made as a series of packets. All the packets are propagated via a chain of routers and various networks to arrive at destination. When a packet reaches at a router, the router has to look up its routing table to determine the next hop for that packet on the basis of packets destination address in the packets IP header as described in Fig. 1. To construct routing tables every router operates IP routing protocols i.e. Open Shortest Path First (OSPF), Border Gateway Protocol (BGP) or Intermediate System-toIntermediate System (IS-IS). When a packet passes over the network, every router does the same steps for discovering the next hop for the packet until it arrive at the destination [7][12]. To provide more interactive application flows with less delay and packet drop thresholds, there is a clear requirement to more effectively use the existing network resources. The process by which it is obtained is called traffic engineering and MPLS provides these features. [6].

Recently the Internet provides us with real-time applications which require to have the minimum possible end-to-end delay. These applications involve voice and video conferencing. Such applications are bandwidth requiring and mostly, a new more capacity connection is required for providing the needed delays, somewhat that it is not cost efficient. Thus, a new way is required in order to operate these applications and even preserve the less end-to-end delay without spending more money on enhancing the network. In interactive applications of real time sound transmission, the whole one way delay requires to be less in order to provide the user an impression of real time reactions. A higher value in the order of 0.1 to 0.5 seconds is needed to achieve this goal. For video application, a video stream should not greater than 250ms. The best attempt protocols cannot assure such limits. MPLS has came out as the primary integration technology for transporting data, voice and video traffic throughout the same network by supplying TE (traffic engineering) and Quality of Service (QoS). Recent works concentrates on comparison of network

Fig. 1 Traditional IP routing

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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 6, June 2015

III. MPLS

MPLS (Multi-Protocol Label Switching) , is a packet switching technology of layer 3 that transmits traffic efficiently and supports Quality of Service (QoS) on the Internet. It is required that MPLS enhance the routing performance in the network layer. MPLS is utilized in Internet Service Provider (ISP) networks and as a backbone to Internet Protocol (IP) to give assured Quality of Service (QoS) and effective bandwidth provisioning in the network [4][5][15]. MPLS provide support to various Layer 2 protocols i.e. Frame relay, ATM and Ethernet. MPLS is capable to demonstrate end to- end IP connections with several QoS characteristics linked with the many transport media [16], its aim is to provide the router a strong power of communication [4]. So it bases particularly on a label (number) introduced between the layer 2(data link layer) and the layer 3(network layer) in the OSI model as depicted in Fig. 2; thus it is called layer 2.5 protocol [2] [4].

Applications TCP

UDP IP MPLS

PPP

FR

ATM

Physical ( Optical- Electrical)

Fig. 2 OSI reference model for MPLS

In a MPLS network, incoming packets are assigned a "label" by a “LER (label edge router)”. Packets are forwarded along a "label switch path (LSP)" where each "LSR (label switch router)" makes forwarding decisions. A. MPLS Shim Header Data packets when arrives at the LER, “Shim Header” is located in between layer 2 and 3 of the OSI model. MPLS Shim Header is integrated into four parts has a overall length of 32 bits; 20 bits for Label, 3 bits for Experimental (EXP), 1 bit for Bottom of Stack and 8 bits for Time to Live (TTL) which is depicted in Fig. 3.

Link Layer Header

MPLS SHIM Header

Network (IP) Layer Header

HH

H

Label (20 bits)

Header

IP Packet data

The MPLS Shim Header contains an identifier is called “Label”. It behaves as an identifier of Forwarding Equivalence Class (FEC), and it is also used for finding the Label Switched Path (LSP). Second field is Experimental field (EXP) which is preserved for the experimental use or are frequently used for providing QoS. Stack field (S) shows whether the label is at the rear of Stack. If the Label is the last entry in stack then the value is adjusted to one otherwise it is zero. The last field is the (TTL) value which decreases by one on each hop as it passes through the LSRs. When the TTL value arrives zero the packet is lost. Label plays a very significant role among all the fields of MPLS shim header. B. MPLS Elements Label: It helps to discover the route that the packet must adopt in the MPLS network which allow the routers to enhance the routing speed. Label Switch Router (LSR): A router which is placed in the MPLS domain and routes the packets on the basis of label switching is known as LSR. When LSR gets a packet it examines the lookup table and finds the next hop, then before sending the packet to next hop it attaches the new label to the header and removes the old label. Label Edge Router (LER): LER manages L3 lookups that is responsible for removing or adding the labels from the packets when they enter into or exit from the MPLS domain. When a packet is entering or leaving the MPLS domain then it has to pass over LER router Label Distribution Protocol (LDP): This is the protocol by which the label mapping information is interchanged among LSRs. It is responsible for demonstrating and preserving labels among routers and switches. Forward Equivalence Class (FEC): FEC is collection of packets where they have related features which are propagated on the same path with the same priority. Label Switched path (LSP): LSP is the path in MPLS domain which is set by signaling protocols. There are number of LSPs in MPLS domain that are developed at ingress router and passes over one or more core LSRs and ends at egress router. MPLS has two planes: 1. Control Plane: Control Plane is used for the label distribution and routing information exchange among adjacent devices. 2. Data Plane: Data Plane is used for propagating packets on the basis of label or destination IP address using LFIB controlled by the control plane. IV. TRAFFIC

EXP S (1 Bit) 3

Fig. 3. MPLS Shim Header

TTL (8 bit)

ENGINEERING IN MPLS NETWORKS The recently developed networks are converged networks; they can transport normal data, voice, videos by utilization of same network resources. Some user data traffics i.e. videos, voice or SQL bank Transactions are more significant and less liberal to delay so they are preferred and dealt on the basis of

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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 6, June 2015

their delivery needs i.e. maximum affordable delay and bandwidth. If the increased number of internet users and various network data traffic types are considered, internet service providers (ISP) dealt with a challenge in the form of Traffic Engineering [20]. The condition of traffic engineering by conventional IP networks is truly a challenging work. In these kinds of networks, IP packets are routed by taken into consideration the Open shortest path first (OSPF) protocol which selects the shortest path from source node to destination node. Though the choice of the shortest paths may preserve network resources, still they may cause to many problems [11]. To manage the problem of packet drop and low delay in the transfer of multimedia applications, it is essential to think of enhancements methods to employ more efficiently on the existing network resources. MPLS-TE is a process that gives this functionality [9]. Though the original thought behind the growth of MPLS was to make easier fast packet switching, presently its primary objective is to support traffic engineering and supply quality of service [14]. When the objective is to obtain the performance aims i.e. traffic placement on particular links and optimization of network resources, Traffic engineering is primarily required. The abstract idea of traffic trunk has been demonstrated for implementing TE in a MPLS area. A traffic trunk is described as a collection of traffic flows placed within a LSP [21][22]. V. SIMULATION METHODOLOGY OPNET Simulator 16.0 is used to create the configuration as indicated in Fig.5 and Fig. 6 for both conventional and MPLS networks. Two scenarios are consisted in the simulation by considering the same network configuration. Scenario 1 is based on IP network without TE and Scenario 2 is based on MPLS network with TE. The results obtained by these simulations are utilized to compare the two networks.

Fig. 4 (Scenario 1)

Fig. 5 (Scenario 2)

The network contains several components: six LSRs (LSR_1, LSR_2, LSR_3, LSR_4, LSR_5 and LSR_6), Two LERs (Ingress LER1and Egress LER2), these routers are connected by PPP adv link work at data rate of 4.5Mbps, Four clients (client_1, client_2, client_3, client_4), two switches (SW1 and SW2), and three servers (voice server, video server and FTP server) are used. The simulation time for each scenario is 400 seconds. The traffic initiates at the 110th second and terminates at the 400th second of the simulation time. One of the primary elements of this simulation is that it considers various network loads condition in the two scenarios. VI SIMULATION AND RESULTS We have compared performance matrices of IP model networks and MPLS_TE. The compared parameters are Delay Variation, End to-End Delay, FTP Response Time and Packet Receive and Send. MPLS TE performs better than conventional IP network model for all the performance parameters. The better performance of MPLS_TE is more apparent, in the situation of heavy load (worst possible network load). All routers are usual IP routers in scenario 1(Fig.4). MPLS definition attribute is not taken into consideration and the packets are propagated by using OSPF protocol, thus all packets are routed over the shortest path only (LER1LSR_4LER2) and doesn't take into account the other two paths. In Scenario2 (Fig. 5) MPLS_TE is carried out by generating LSPs, and describing how traffic is allotted to the corresponding LSPs. The network load is equally disseminated among the three LSPs :(LER1LSR_1LSR_2< >LSR_3,LER1LSR_4LER2 and LER1LSR_5LSR_6LER2) this makes MPLS an effective technology.

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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 6, June 2015

Fig. 6 Video Packet Send and Received

Fig.6 and Fig.7 provides the mean number of packets sent and obtained in both conventional IP networks and MPLS for both video and voice traffic. Simulation result presents that MPLS model provides more throughput as compared to the IP model, and indicates that in the IP network Video and voice packets start to loss sooner in comparison of MPLS network In heavy load condition, Fig. 8 and Fig 9 shows the end to end delay of video and voice traffics. It is clear that MPLS has lesser delay as compared to the IP model in the situation of heavy load (worst network load). In the situation of both interactive voice the delay is less than 200 ms and in video the delay is less than 250ms. The delay or jitter variation is approximately (30-50) ms. The delay variation of video and voice traffics are shown in Fig.10 and Fig. 11. The delay variation result presents that MPLS TE has lesser delay in comparison of IP network model in the case of worst possible load like the end to end delay results. By the simulation results in Fig.12 we observe that Voice Packet Jitter enhanced in both network model but in MPLS TE jitter is much lesser as compared to IP network model. The FTP response time of MPLS TE (Traffic Enigineering) was more lesser than IP network model as in Fig. 13, also the mean of packet obtained in MPLS TE better than IP network model as shown in Fig. 14.

Fig. 8 Video Packet End to End Delay

Fig. 9 Voice Packet End to End Delay

Fig. 10 Video Packet Delay Variation

Fig. 7 Voice Packet Send and Received

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International Journal of Science, Engineering and Technology Research (IJSETR), Volume 4, Issue 6, June 2015

Fig. 11 Voice Packet Delay Variation

Fig. 14 FTP Traffic Received

CONCLUSION

Fig. 12 Voice Packet Jitter

The primary aim of the paper is based on the performance evaluation of MPLS TE and conventional IP network for Non Real Time applications and multimedia applications (Video Conferencing, VoIP). After the simulation results it can be concluded that MPLS TE gives best solution in carrying out these applications in comparison of conventional IP networks. Also this paper describes poor link usage in conventional IP networks. It is found that network set up with OSPF routing techniques are not able of managing the incoming traffic effectively. With the increment in network traffic, shortest path from source to destination is heavily congested and cause to drop of transmission data. We have presented and simulated the MPLS TE is able of managing incoming traffic effectively by disseminating the traffic over many LSPs according to FEC which is not capable to obtain in conventional routing protocol. By the results analysis, it is clear that with suitable MPLS TE employed to the network, the performance of the network is importantly enhanced. Thus, network providers and Internet service providers appear to have been taking the benefit of this technology to give flexible support for a broad range of services i.e. construct reliable internet services, simplify network architecture and overcome some available infrastructure restrictions. REFERENCES

Fig. 13 FTP Download Response Time

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