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
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.
USA: Addison Wesley Professional, 2005.[7]. M.
Morrow and A. Sayeed, MPLS and Next-Generation
Networks: Foundations for
NGN and Enterprise Virtualization. USA: Cisco Press, 2006.
[8]. K. Jannu and R. Deekonda, “OPNET simulation of
voice over MPLS with considering Traffic
Engineering,” Blekinge Institue of Technology, 2010.[9]. M.
Gupta, Building a Virtual Private Network. Ohio: Premier
Press, 2003.
[10]. Gold Sim Technology Group, “Simulation,” What
is Simulation. [Online]. Available: http://
www.goldsim.com/Content.asp?PageID=91.
[Accessed: 10-Jun-2015].