a review paper: analysis of ospf & ripv2 over mpls vpn with opnet simulation ·  ·...

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Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in Imperial Journal of Interdisciplinary Research (IJIR) Page 469 A Review Paper: Analysis of OSPF & RIPv2 over MPLS VPN with OPNET simulation Edmira Xhaferra Lector, Computer Science Department, Aleksander Moisiu University ABSTRACT- There are many disadvantages (cost, lack of security, difficult to manage large networks, support to non- sensitive applications, delay, etc.) associated with traditional networking, IP network, ATM and Frame relay networking. In this thesis, we are trying to build a better understanding to MPLS VPN and we researched to analyze the behavior of OSPF and RIPv2 based MPLS- BGP VPN architectures by using intense VoIP traffic. Then it comes with an OPNET simulation process and scenarios for MPLS-BGP VPN. At last, the conclusion is made: OSPF based MPLS-BGP VPN architecture has lower VPN delay, background traffic Flow delay, LSP delay and point- to-point Queuing delay, and has better performance in VPN load and VPN throughput that can acquire customer satisfaction and confidence as compared to the RIPv2 based MPLS-BGP VPN architecture. Keywords- IP, VoIP, MPLS, VPN, QoS, MPLS VPN I. Introduction Voice over Internet Protocol (VoIP) is an umbrella term for a family of transmission technologies to provide voice communication over IP networks like the internet and Public Switched Telephone Network (PSTN). The basic step in the Internet phone call is the conversion of voice signals into digital format that outputs the translation of the signal into Internet Protocol (IP) packets for transmission over the Internet. The process is reversed at the receiving end [1]. In one of the Telecommunications Industry Association (TIA) report says that residential VoIP consumers are more than tripled in 2005 and predicted an annual growth of more than 40% during 2009. This would report more than 18 million VoIP connections. This shows that VoIP is not only growing rapidly, also it is here to stay. The adoption of VoIP in small to large businesses has also been great. Traditional communication systems are being replaced at a rapid pace by enterprise business communication tools that offer feature-rich and cheaper way of communicating with your contacts [2]. Recently VoIP technologies have advanced to provide tremendous opportunities for service providers, as one can use a single IP network for both data and voice communication in cost-effective and reliable manners. Service providers are now adopting VoIP technologies, to provide new services and applications to accommodate their customers needs. One major VoIP infrastructure deployment issue for service providers is to maintain high quality of communication services to the customers [3]. This paper will focus on the implementation of Quality of Service (QoS) in MPLS VPN backbone with VoIP, using the OPNET simulation tool. According to our knowledge and search, I couldn’t find any information regarding VoIP over MPLS VPN backbone with IP QoS. This motivated me to do scientific research to analyze the behavior of the MPLS VPN with QoS for VoIP traffic. The following steps will be involved to answer the questions and to get the results. Simulation design MPLS VPN configuration with interior routing protocols (RIPv2, OSPF) because it occurs within an autonomous system and exterior routing protocol (BGP) because it occurs between autonomous systems. VoIP traffic configuration MPLS VPN QoS and performance measuring parameters: This thesis presents the benefits of MPLS VPN with IP QoS backbone network with VoIP traffic when simulating the network using OPNET. Analysis of simulation results provide, which scenario will be a better voice communication solution for the customer with respect to MPLS VPN QoS and service reliability. The simulation configurations and results will be presented as images, tables and graphs. II. Voice over Internet Protocol (VoIP) Voice over Internet Protocol, also known as (VoIP/IP Telephony/Internet telephony/ Digital Phone) is the routing of voice over the IP network and the voice data travels through packet-switched network. Our home phone is based on an analogue system, while VoIP has digital one. In VoIP enabled phone, voice is converted into packets; compressed for efficiency and then transferred to the connection. The process is reversed on the other side of the connection. Protocols carry voice signals over the IP networks are referred to as VoIP protocols. VoIP traffic can be deployed on any IP network instead of private building wide Local Area Network (LAN) that lacks an internet connection [2]. VoIP Features With VoIP we can make calls with IP phones from anywhere we have access to our high speed internet connection to

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Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 469

A Review Paper: Analysis of OSPF & RIPv2 over MPLS

VPN with OPNET simulation

Edmira Xhaferra Lector, Computer Science Department, Aleksander Moisiu University

ABSTRACT- There are many disadvantages (cost, lack of security,

difficult to manage large networks, support to non- sensitive

applications, delay, etc.) associated with traditional networking, IP

network, ATM and Frame relay networking. In this thesis, we are

trying to build a better understanding to MPLS VPN and we

researched to analyze the behavior of OSPF and RIPv2 based MPLS-

BGP VPN architectures by using intense VoIP traffic. Then it comes

with an OPNET simulation process and scenarios for MPLS-BGP

VPN. At last, the conclusion is made: OSPF based MPLS-BGP VPN

architecture has lower VPN delay, background traffic Flow delay,

LSP delay and point- to-point Queuing delay, and has better

performance in VPN load and VPN throughput that can acquire

customer satisfaction and confidence as compared to the RIPv2

based MPLS-BGP VPN architecture.

Keywords- IP, VoIP, MPLS, VPN, QoS, MPLS VPN

I. Introduction

Voice over Internet Protocol (VoIP) is an umbrella term for a

family of transmission technologies to provide voice

communication over IP networks like the internet and Public

Switched Telephone Network (PSTN). The basic step in the

Internet phone call is the conversion of voice signals into

digital format that outputs the translation of the signal into

Internet Protocol (IP) packets for transmission over the

Internet. The process is reversed at the receiving end [1]. In one

of the Telecommunications Industry Association (TIA)

report says that residential VoIP consumers are more than

tripled in 2005 and predicted an annual growth of more than

40% during 2009. This would report more than 18

million VoIP connections. This shows that VoIP is not

only growing rapidly, also it is here to stay. The adoption

of VoIP in small to large businesses has also been

great. Traditional communication systems are being

replaced at a rapid pace by enterprise business

communication tools that offer feature-rich and cheaper way

of communicating with your contacts [2]. Recently

VoIP technologies have advanced to provide

tremendous opportunities for service providers, as one can

use a single IP network for both data and voice

communication in cost-effective and reliable manners. Service

providers are now adopting VoIP technologies, to provide

new services and applications to accommodate their

customers needs. One major VoIP infrastructure

deployment issue for service

providers is to maintain high quality of communication

services to the customers [3].

This paper will focus on the implementation of Quality of

Service (QoS) in MPLS VPN backbone with VoIP, using the

OPNET simulation tool. According to our knowledge and

search, I couldn’t find any information regarding VoIP over

MPLS VPN backbone with IP QoS. This motivated me to do

scientific research to analyze the behavior of the MPLS VPN

with QoS for VoIP traffic. The following steps will be

involved to answer the questions and to get the results.

• Simulation design

• MPLS VPN configuration with interior routing

protocols (RIPv2, OSPF) because it occurs within an

autonomous system and exterior routing protocol (BGP)

because it occurs between autonomous systems.

• VoIP traffic configuration

• MPLS VPN QoS and performance measuring

parameters:

This thesis presents the benefits of MPLS VPN with IP QoS

backbone network with VoIP traffic when simulating the

network using OPNET. Analysis of simulation results provide,

which scenario will be a better voice communication solution

for the customer with respect to MPLS VPN QoS and service

reliability. The simulation configurations and results will be

presented as images, tables and graphs.

II. Voice over Internet Protocol (VoIP)

Voice over Internet Protocol, also known as (VoIP/IP

Telephony/Internet telephony/ Digital Phone) is the routing of

voice over the IP network and the voice data travels

through packet-switched network.

Our home phone is based on an analogue system, while VoIP

has digital one. In VoIP enabled phone, voice is converted into

packets; compressed for efficiency and then transferred to the

connection. The process is reversed on the other side of the

connection. Protocols carry voice signals over the IP networks

are referred to as VoIP protocols. VoIP traffic can be deployed

on any IP network instead of private building wide Local

Area Network (LAN) that lacks an internet connection [2].

VoIP Features

With VoIP we can make calls with IP phones from anywhere

we have access to our high speed internet connection to

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 470

anyone. Some users use a specially developed softphone on

their computers to access their VoIP services. Most companies

that provide traditional phone services charge extra for

additional features but with VoIP these features come as

standard. Such as [4]:

Caller ID

Call waiting

Call transfer

Repeat dialing

Return Call

Conference calls

Call filtering

Voice mail

Fake call

Messaging

There are many cost saving benefits. Network administrators

have to maintain only one network for VoIP and Data instead

of two networks. The portability of the phone system is also

greatly simplified. VoIP systems are extremely portable

because its configuration can be done via using a web

interface. All these features lead to lower ongoing cost for an

organization [4].

Layers of VoIP Network

VoIP networking can be described in better way by using the

Open Systems Interconnect (OSI) reference model that

describes the data communications process. This reference

model consists of seven layers: physical, data link, network,

transport, session, presentation, and application. The main

purpose this model is to integration of different types of

networks and to provide standardized platform for engineers.

This model works similar with VoIP as it works with other

type of networks [4][2].

Fig 1: VoIP network layers

Protokollet

VOIP uses the Internet Protocol (IP) to transmit voice packets

for communication via internet, intranet or LAN. VoIP uses

combination of different methods to categorize areas:

Voice session control and data transmission protocols

used to set up, tear down calls and transformation of

information.

CODECs used for conversion and compression of

voice.

The main aim of protocols in VoIP is to initiate and

maintain communication links between endpoints. By

performing this task these protocols are known as

VoIP session protocols or VoIP signaling protocols

[5]. The main differentiating reason between these

signaling protocols is how these protocols were

designed to handle the different types of call paths.

III. Multiprotocol Label Switching (MPLS)

Multiprotocol Label Switching (MPLS) has been here in

communication industry for many years. As discussed in RFC-

3031, MPLS combined the advantages of ATM and Layer-3

approach of IP but it has an independent architecture for fast

packet switching and routing. MPLS is a way of tunneling IP

data-grams, within and among independent systems. It also

treats the encapsulated IP datagram as raw data and does not

access it in the tunnel.[6].

Fig 2. MPLS label encapsulation

In MPLS networking, simple and fixed length labels are used

to build a label to label mapping between network routers.

These labels are attached to packets to forward them through

the network by label switching instead of IP switching. The

label switching technique is not new, as it is used in Frame

Relay and ATM. This high speed switching mechanism in

MPLS is possible by inserting labels before the packets that

enable the hardware to switch packets between links. In

essence, the MPLS combines the advantages of IP routing and

the simplicity of label switching of Frame Relay or ATM.

MPLS devices operate on both the IP layer as well as the

label-switching layer. Because of this nature, MPLS devices

are called Label Switch Routers (LSRs).

The label-Switched Paths (LSPs) are virtual tunnels, used for

data transmission in MPLS network. These LSPs are formed

by a series of labels from source to destination. The “two-

label” approach is proposed by Martini, becomes the most

popular way for encapsulating the Layer-2 protocols. This

method uses the following labels :

1. Tunnel Label: decides which LSP will be use for the

packet transmission from the ingress to egress LSRs.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 471

2. VC Label: provides Layer-2 forwarding information

to egress LSR.Tunnel Label (etiketa tunel): vendos

cila LSP do të përdorë për transmetimin e paketës

nga hyrja në dalje e LSRs.

MPLS makes use of existing IP routing protocols like Border

Gateway Protocol (BGP), Resource Reservation Protocol

(RSVP), Open Shortest Path First (OSPF), and etc. MPLS has

defined a new set of signaling and routing protocols such as

Label distribution Protocol (LDP), Constraint-based LDP

(CR-LDP) and Resource Reservation Protocol – Traffic

Engineering (RSVP-TE). MPLS has traffic management and

QoS mechanisms to manage traffic flows. Specifically, MPLS

provides traffic management capabilities such as traffic

policing, congestion management, traffic shaping and priority

queuing. In summary, MPLS addresses many problems

concerning today’s networks such as speed, scalability, QoS

management and traffic engineering. With its powerful new

features, MPLS has become a next generation network (NGN)

solution for services such as data, voice and video over the

same network.

MPLS Architecture

Mainly an MPLS network consists of LSR and MPLS nodes.

An LSR runs the MPLS protocol to provide label binding to

Forward Equivalence Classes (FECs), IP packet forwarding,

and carry the IP forwarding decision. An MPLS node is an

LSR, except that it does not provide IP packet forwarding

based on prefixes [34]. The key advantage of MPLS

architecture is the division into two planes:

Data plane: that contains the information required to

transfer a packet.

Control/Signaling plane: that allocates the transfer

information.

This division allows many applications to be developed and

deployed in a flexible, scalable and reliable manner.[7]

FiG 3. Basic architecture of MPLS IP routing

Label Switched Routers (LSR)

An LSR is a router that has the capability to understand MPLS

labels and responsible for receiving and transmitting a

labeled packet on a data link in MPLS network [8].

Three operations are associated with LSRs, pop, push and

swap. In MPLS network, there are three types of LSRs:

Ingress LSRs: receive an unlabeled packet, add a

label to that packet and send it via data link.

Egress LSRs: receive labeled packets, remove the

label or set of labels and send them via data link.

Intermediate LSRs: perform an operation on

incoming labeled packet and switch the packet on the

correct data link.

Fig 4. Label Switched Routers (LSRs)

Label Switched Paths (LSP)

An LSP consists of a sequence of LSRs that switch a labeled

packet through an MPLS network. In MPLS network, the first

LSR of an LSP is the ingress LSR for that LSP, and the last

LSR of the LSP is the egress LSR. [8]. The intermediate

LSRs are working in between the ingress and egress LSRs.

Fig 5. Label Switched Paths (LSPs)

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 472

IV. Virtual Private Network (VPN)

There are many terms used to define, describe and categorize

the VPN functionalities have led to confusion about VPNs

[38]. The Internet Engineering Task Force (IETF) provides the

standardized definition of a VPN.

“A network in which connectivity among multiple private

Wide Area Networks (WANs) is deployed using shared IP

infrastructure with the same policies as a private network.”

A VPN is also described as: an extension of a private intranet

through a public network infrastructure to provide a secure,

cost effective and reliable communication channel between

two ends. The private tunnels provide help in this extension of

the private intranet to enable the point-to-point communication

for data exchange. [9]

Fig 7. Single MPLS tunnel used to connect multiple VPNs

MPLS VPN Architecture

VPN Devices

Fig 6. Typical VPN setup

By splitting the different technologies into overlay and

network based VPNs can help us to evaluate the current time

real time problems such as the overlay arrangement doesn’t

support scalability of client connections. The problem in this

case is because of the requirement policy for every connection

from site to many sites, and routing adjacencies over these site

to site connections. But in network based solutions sites are

connected to locally attached PE routes. So, the network based

category is more adoptable than overlay category. In 21st

century, we moved toward the deployment of network-based

Layer-3 VPN (2547bis) solution that is the main base line for

MPLS VPN architecture.

VPN devices are categorized in two main areas:

Customer network devices

Service Provider (SP) network devices

V. MPLS Virtual Private Network (MPLS VPN)

MPLS can be used to provide VPN solutions at either Layer-2

or Layer-3 of the OSI Reference Model. MPLS capable

network can provide support for MPLS tunnels, used to

establish layer-2 VPNs in Frame Relay, ATM, and etc. These

tunnels provide a virtual wire that connects source and

destination of the VPN. Alternatively, encapsulated MPLS

packets can provide some other tunneling mechanism for

transmission of these packets across the IP core network. This

tunneling mechanism can be useful when MPLS is used within

the VPN, and reduce the number of tunnels across the

network.

Fig 8. MPLS VPN architecture

MPLS VPN Network Components

MPLS VPN network has following types of devices as shown

in figure 9.

Customer network (C-network): a network

administered by the end user attached to the Layer 3

MPLS VPN service.

Customer Edge (CE) router: a router that provides a

gateway between the C-network and the P-network.

Provider network (P-network): the core MPLS

network administered by the service provider.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 473

Provider Edge (PE) router: edge router that provides

VPN and service delivery.

Provider (P) router: An MPLS router deployed

within the P-network with no edge service

attachments.

Autonomous System Boundary Router (ASBR):

provides attachment to an adjacent autonomous

system.

Fig 9. Basic components of MPLS VPN

VI. OPNET Simulation

The main task of this empirical study based on OPNET

simulation is to analyze the behavior of MPLS VPN with

respect to different performance metrics, i.e., VPN delay, VPN

load (bits/s and packets/s), and throughput (bits/s and

packets/s) according to our network design. To accomplish

this task VoIP traffic is used across the IP QoS enabled MPLS

VPN backbone that consists of interior gateway protocols

(IGP) RIPv2, OSPF, and exterior gateway protocol (EGP)

BGP. The results obtained by the simulation are analyzed to

determine the behavior of MPLS VPN backbone. This

facilitates to predict the weakness and strengths before real

time implementation of the model [10].

Network Scenarios

Depending on how the MPLS VPN is implemented by using

IGP (RIPv2 or OSPF) and EGP (BGP), we have the following

scenarios:

1. QoS enabled MPLS VPN backbone with IGP

(RIPv2) and EGP (BGP).

2. QoS enabled MPLS VPN backbone with IGP (OSPF)

and EGP (BGP).

The considered network topology of MPLS-BGP VPN for

both cases(RIPv2 or OSPF) is shown in figure 10.

Fig 10. MPLS-BGP VPN with IGP (RIPv2 or OSPF)

Network Components

All the above simulation models have the following network

elements.

Autonomous Systems AS

AS-1

4 Provider routers (P)

3 Provider Edge routers (PE)

AS-2

Enterprise A

Site-1

o 2 Customer routers (C)

o 1 Customer Edge router (CE)

Site-2

o 2 Customer routers (C)

o 1 Customer Edge router (CE)

MPLS VPN Configuration

All the scenarios illustrate the use of VPNs for communication

between two sites of Enterprise network A that uses a VPN

named "Yellow_VPN". All routers are interlinked by using

PPP_SONET_OC3 (155Mbps) links.

Fig 11. VPN configuration parameters on all PEs

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 474

BGP is configured between all PEs, i.e. all PEs are BGP

neighbors. Routes between PE and CE are shared using BGP,

i.e. PEs and CEs are BGP neighbors of each other.

Multiple cases of VoIP Traffic

In the analysis of MPLS VPN, we have used VoIP traffic. The

main reason of running VoIP traffic for analyzing MPLS VPN

is that it is highly delay sensitive as compared to video and

other data traffic. We have used following to cases of VoIP

traffic considering different call rate per hour. For 500calls per

hour the average traffic load in is app. 4,000,000 bits/sec, and

for 2500 calls per hour the average traffic load is app.

20,000,000 bits/sec.

Fig 12. Comparison of total VoIP traffic in bits/sec, for 500

and 2500 calls/hour

VII. DES Statistics

For analysis of results, following discrete event simulation

(DES) statistics are chosen:

• MPLS VPN

o VPN Delay (sec)

o VPN Load (bits/sec)

o VPN Load (pkts/sec)

o VPN Throughput (bits/sec)

o VPN Throughput (pkts/sec)

• IP background traffic Delay (sec)

• Site1-to-Site3 Path Statistics

o Flow Delay (sec)

o Flow Traffic In (bits/sec)

o Flow Traffic Out (bits/sec)

o LSP Delay (sec)

o LSP Traffic In (bits/sec)

o LSP Traffic Out (bits/sec)

Case 1 - VPN Load & Throughput (bits/sec) for 500 calls

In this case RIPv2 has greater load than OSPF. It is observed

that the sample mean of VPN load for RIPv2 is 3,863,662.369

bits/s and for OSPF is 3,814,132.303 bits/s.

Fig 13. VPN load (pkts/sec) & Throughput (bits/sec) for 500

VoIP calls

Case 2 - VPN Load & Throughput (bits/sec) for 2500 calls

Fig 14. VPN load (pkts/sec) & Throughput (bits/sec) for 2500

VoIP calls

In both cases, the RIPv2 has greater VPN throughput

according to the VPN load. This is because of the RIPv2

multicast of routing tables but higher load on network

means that RIPv2 is consuming more resources as

compared to OSPF. In this prospect OSPF has an

advantage over RIPv2. Similar with Load & Throughput

(pkts/sec) and OSPF has advantage over RIPv2.

Case 3 - IP Background Traffic Delay (sec)

It is observed that the RIPv2 has greater delay for

VoIP background traffic in MPLS-BGP VPN backbone as

compared to OSPF. The sample mean of traffic delay for

RIPv2 is 0.0001382s and for OSPF is 0.0001380s.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 475

Fig 15. IP background traffic delay (sec) for 500 VoIP calls

Similar with IP background traffic delay (sec) for 2500 VoIP

calls, in both cases, OSPF background traffic delay is less than

RIPv2.

Case 4 - Flow Delay (sec)

The packet flow delay in the LSP of MPLS-BGP VPN from

Site1_PE to Site3_PE with respect to RIPv2 and OSPF is

shown in figure 16. The sample mean of packet flow delay for

RIPv2 is 4.50E-006s, and the sample mean of packet low

delay for OSPF is 4.38E-006s.

Fig 16. Site1-to-Site3 flow delay (sec) for 500 VoIP calls

For 2500 VoIP calls

The sample mean of packet flow delay for RIPv2 is 1.09E-

005s, and the sample mean of packet flow delay for OSPF is

1.06E-005s is shown in figure 17. OSPF has an advantage

over RIPv2, but the extensive VoIP traffic has showed greater

effect on the performance of RIPv2 as compared to OSPF,

w.r.t the packet flow delay.

Fig 17. Site1-to-Site3 flow delay (sec) for 2500 VoIP calls

Case 4 - LSP Delay (sec)

Delay experienced by Packet in the LSP. i.e. Time spent by

the packet within the Label Switched Path.

The LSP delay of MPLS-BGP VPN from Site1_PE to

Site3_PE with respect to RIPv2 and OSPF is shown in figure

18. The sample mean of LSP delay for RIPv2 is 4.72E-006s,

and the sample mean of LSP delay for OSPF is 4.51E-006s.

Fig 18. Site1-to-Site3 LSP delay (sec) for 500 VoIP calls

And for 2500 calls, the sample mean of LSP delay for RIPv2

is 1.104E-005s, and the sample mean of LSP delay for OSPF

is 1.06E-005s. OSPF has advantage over RIPv2.

VIII. Conclusion

1. MPLS VPN with IP QoS influences delay in the

VoIP network

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-2 , 2016 ISSN : 2454-1362 , http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 476

2. MPLS VPN based on interior routing protocol

(OSPF) and exterior routing protocol (BGP) with IP

QoS is a best scenario for VoIP traffic w.r.t VPN

delay, load and throughput, and Site-to-Site Flow

delay and LSP delay, and End-to-End Queuing delay

3. MPLS-BGP VPN architecture (hybrid VPN solution)

and found out that this architecture is scalable and

flexible enough to provide well-organized voice

packet transmission, load balancing, consistency,

data security, network isolation from other networks

and end-to-end controlled connectivity with QoS

guaranteed.

Reference:

[1]. E. B. Fjellskål and S. Solberg, “Evaluation of Voice

over MPLS (VoMPLS) compared to Voice over IP

(VoIP),” Høgskolen I Agder, 2002.

[2]. J. Davidson, J. Peters, M. Bhatia, S. Kalidindi, and

S.Mukherjee, Voice over IP Fundamentals, 2nd ed. USA:

Cisco Press, 2006.

[3]. B. Alawieh, R. Ahmed, and H. T. Mouftah,

“Performance measurement for voice services in

heterogeneous wired networks,” Innsbruck, Austria, pp. 1-

5,2008.

[4]. B. Davie and A. Farrel, MPLS: Next Steps. USA:

Morgan Kaufmann, 2008.

[5]. D. Field, Fire the Phone Company: A Handy Guide to

Voice over IP. Peachpit Press, 2005.

[6]. J. C. Snader, VPNs Illustrated: Tunnels, VPNs, and IPsec.

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Morrow and A. Sayeed, MPLS and Next-Generation

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