VoIP Call Processing in the MPLS Network

8/13/2019 VoIP Call Processing in the MPLS Network

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Architecture of End-to-End QoSfor VoIP Call Processingin the MPLS Network

2004. 9. 29

National Computerization Agency

(Republic of Korea)ChinChol Kim

[mail to] : [email protected]

Fifth International Workshop on Quality of future Internet Service(QofIS04)


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Contents

Abstract1. Introduction2. QoS Architecture for VolP in the NGN3. Architecture of End-to-End QoS for SIP

Call Signaling

4. Implementation5. Performance Analysis6. Conclusion


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Abstractq

This paper proposes the architecture of end-to-end QoS for VoIP callprocessing in the MPLS-based NGN supporting the IPv6

The architecture include QoS resource management and

differentiated call processing by extending SIPq Also, we analyze the performance of call processing

in the MPLS networkq

A performance analysis shows that there is a considerable difference in end-to-end call setup delay depending on service priority , insetting up SIP calls in the MPLS network


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1. Introduction (1)q

With the fast development of network technology, VoIP is one of the core technology of NGN and VoIPs

core protocols are H.323 and SIP signaling protocols At present, the text-based SIP has been adopted as the

standard for NGNq SIP must provide

a service quality better than the quality provided by thePSTN for call setup in NGN

and offer priority-based call processing , depending onthe traffic properties of application services


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1. Introduction (2)q

The VoIP service in NGN must guarantee call quality for voice data transfer and call setup quality forcall setup , in which the latter must precede the former

q On the other hand, call setup quality does notguarantee end-to-end QoS , since it goes through MPLSrouter and multiple SIP servers

q In order to resolve this problem, This paper proposes the architecture of end-to-end QoS for

VoIP call processing in an MPLS-based NGN QoS resource management coordinates service priority in call

processing Differentiated call processing technology processes calls,

applying the service priority negotiated in the SIP server


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2. QoS Architecture for VolP in the NG

q The call quality refers to speech coding distortion, terminal noise and

overall delay caused by packetization, buffering, codecs can be guaranteed by QoS technology, including MPSL,

Diffserv and IntServq On the other hand, call setup quality

refers to guaranteeing call setup, which is classified intocall setup delay in the network and VoIP server

Call setup delay in the network can be guaranteed throug

QoS technology, such as MPLS and DiffServ However, there is no standard technology that ensurescall setup delay in the VoIP server

q Therefore, we need various forms of QoS mechanisms in the VoIP server to

guarantee end-to-end QoS for call setup quality


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. rc ec ure o n - o- n ofor SIP Call Signaling

MPLS NetworkSIP Server SIP Server

Local Network A Local Network B

3. Priority Marking &Differentiated Call Processing

Router

LER

End-to-end QoS basedCall Processing

SIP UA SIP UA

R e s e r v e d L

S P

LSR

SIP Server

SIP UA

LER

Router

LSR

LSR

LSR

LER

Router

. LSP Setup

LER : Label Edge RouterLSR : Label Switching Router

2. Service Priority Negotiation

LERLER


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UDP

IPv6

UDP

IPv6

3.1 System structureUser Database

SIP6d Daemon

QRM

DQoSPSMP

Receiver

SMP : SIP Message ParserQRM : QoS Resource ManagementQRR : QoS Resource Requester

DQoSP : Differentiated QoS ProcessorSLS : SIP Location Server

UAC : User Agent ClientUAS : User Agent ServerSPC : SIP Proxy Server

SRS : SIP Redirect Server

SPS SRSSLS

SIP Ex-tension

UAS

QoSMarker

UAC

QRR

SIP6 UA


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3.2 SIP Message Extension and Flow (1)

QOSREQUESTQOSREQUEST method is used by SIP UA to negotiate servicepriority with the SIP server. It sets up the service priority requestedby the user through the Qosinfo header field.

Method Type Description

QOSWITHDRAW QOSWITHDRAW method is used by SIP UA to nullify negotiatedservice priority. It specifies the service priority to be nullified throughQosinfo header field.

Table 1. SIP Method extension

Qosinfo

Syntax Formalism : Qosinfo:desired/release=ServiceLevelDesired header option is used to set up the service priorityrequested by the user in QOSREQUEST method. It is also used to setup the negotiated service priority in 200 OK response messages.Release header option is used to release the service prioritynegotiated by the user in QOSWITHDRAW method and 200 OKresponse messages.

Header Type Description

Qosmark

Syntax formalism : Qosmark : ok / noThis is included in request/response message transferred to SIPmessage pass. If the header option in Qosmark header field is Ok,

the SIP server applies differentiated call processing technology.If it is No, the SIP server doesnt.

Table 2. SIP Header and Header Option extension


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IP UA Client SIP Server SIP Server SIP UA Ser

3.2 SIP Message Extension and Flow (2)

Q O S REQ U ES T 2 0 0 O K

I N V I T E

1 0 0 T r y i ng I N V I T E

I N V I T E 1 0 0 T r y i ng

1 8 0 R i ng i ng

2 0 0 O K

2 0 0 O K

Q O S W I T H DRAW

2 0 0 O K

...

1. Resource negot i at i on fl ow

2. Di fferent i at ed call processi ng fl ow

3. Resour ce rel ease f l ow

Qosmark header insert

1 8 0 R i ng i ng 1 8 0 R i ng i ng 2 0 0 O K

A C K

A C K

A C K


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3.3 Differentiated Call Processing AlgorithmMessage Processing Buffer

Insert Qosmark headerincluded No header option

to SIP Message

Premium Buffer Assured Buffer Normal Buffer

Scheduling

InsertExecution Buffer Message Parsing

Qosmark HeaderExit?

IPv6 Flow LabelField Value?

Premium Normal

Assured

Admission Controller

Classifier

Scheduler

Qosmark HeaderOption Value?

Yes Ok

No

Priority Authentication? No

Priority value set to IPv6 flow label field,Insert Qosmark header included Ok

header option to SIP Message

Yes No

l


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4. Implementation

qWe referred to the SIP source code fromColumbia University SIP6d is implemented using C language in Linu

system that supports IPv6 The SIP UA is implemented using Tcl/Tk and C++ MySQL is used to manage user information

The major modules are implemented using POSIXthread technology

5 P f A l i (1)


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5. Performance Analysis (1)

IPv6 DNSServer(Linux)

IPv6 MPLSRouter(Linux)

Test ProgramClient

SIP6d(Linux) SIP6d(Linux)

Test ProgramServer

SIP Signaling Data



It is composed of two Linux servers with SIP6d, two PCs with test programs, and

three Linux servers, which are used as routers with MPLSmodules based on the software provided by Sourceforge.net


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5. Performance Analysis (2)The experiment has adopted the following procedure

Firstly , the test client program generate equal number ofthree different INVITE messages and simultaneouslytransfers to SIP6d in the number of 50, 100, 150, 200, 250,and 300 messages of each priority.

Secondly , the two SIP6ds process the received messages,using differentiated call processing technology and transfethem to the test client server. Each message is moved alonthe LSP path predetermined in the three routers

Next , the test server program transfers 200OK responsemessages. Then, the test client program receives 200OKresponse messages coming through two SIP6ds, andmeasures session setup time, i.e. the average end-to-endcall setup delay time. For the comparison , INVITEmessages without priority are generated and sent to theSIP6d without a differentiated call processing function ithe number of 150, 300, 450, 600, 750, and 900.

5 P f A l i (3)


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00.050.1

0.150.2

0.250.3

0.350.4

0.450.5

0.550.6

0.650.7

0.750.8

0.850.9

0.951

50x3 100x3 150x3 200x3 250x3 300x3

Premium PriorityAssured Priority

Normal Priority

Time(sec)

MessageNumber

00.050.1

0.150.2

0.25

0.30.350.4

0.450.5

0.550.6

0.650.7

0.750.8

0.850.9

0.951

150 300 450 600 750 900

Time(sec)

MessageNumber

Fig. 6. End-to-End Call Setup Delay in SIP6d over MPLS Network

(a) End-to-end Call Setup Delay in SIP6dsupporting Differentiated Call Processing (b) End-to-end Call Setup Delay in SIP6d

As one can see from the graph , the SIP6d that supports differentiated call processingshows a difference in call setup delay when processing messages. In particular, INVITEmessages with premium priority have very short call setup delay. Therefore, we can seethat INVITE messages with higher service priority have far shorter call setup delay than

those with lower service priority. However, SIP6d that does not support differentiatedcall processing has no difference in call setup delay.

5 P f A l i (4)


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Fig. 7. End-to-End Call Setup Delay in SIP6d over Non-MPLS Network

(a) End-to-end Call Setup Delay in SIP6dsupporting Differentiated Call Processing

(b) End-to-end Call Setup Delay in SIP6d

00.050.1

0.150.2

0.250.3

0.350.4

0.450.5

0.550.6

0.650.7

0.750.8

0.850.9

0.951

50x3 100x3 150x3 200x3 250x3 300x3

Premium PriorityAssured PriorityNormal Priority

Time(sec)

MessageNumber

00.050.1

0.150.2

0.250.3

0.350.4

0.450.5

0.550.6

0.650.7

0.750.8

0.850.9

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150 300 450 600 750 900

Time(sec)

MessageNumber

Also, End-to-end call setup delay over MPLS Network show better performancethan end-to-end call setup delay over Non-MPLS Network

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6. ConclusionThis paper proposes an architecture of end-to-enQoS for VoIP call processing in the MPLS network

The differentiated call processing technology reserveresources by extending SIP , and minimizes end-to-encall setup delay for specific calls by using prioritscheduling technology in the application level

It also has an advantage of setting up the service prioritthrough the flow label field of IPv6 header , considerinfuture MPLS label mapping

A performance analysis has showed that SIP6d provides a very fast processing rate fomessages with high service priority These results prove that we can provide excellen

performance for call setups that require real-time oservice priority when providing future voice service ithe NGN based on MPLS


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VoIP Call Processing in the MPLS Network