Jose Saldana, Jenifer Murillo, Julian Fernandez-Navajas, Jose Ruiz-Mas, Eduardo Viruete, Jose I. Aznar. "QoS and Admission Probability Study for a SIP-based Central Managed IP Telephony System". In Proc. New Technologies, Mobility and Security, NTMS 2011, 5th International Conference on, Paris. Feb. 2011. ISBN: 978-1-4244-8704-2

1. Presentación
<>
Jose Saldana
Jenifer Murillo
Julián Fernández Navajas
G RUPO DE
T ECNOLOGÍAS DE LAS
COMUNICACIONES
CPS - University of Zaragoza, Spain
José Ruiz Mas
Eduardo Viruete Navarro
José I. Aznar

2. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

3. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

4. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 4
Introduction
- VoIP is replacing traditional telephony
systems.
- Software-based solutions allow a simple
PC to assume the role of the PBX.
- This is interesting for SME that want to
avoid the costs of proprietary systems.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

5. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 5
Introduction
- VoIP is a real-time service, but it uses a
network designed for best effort services.
- Users demand a QoS similar to PSTN.
- Need of solutions to add quality to IP
networks.
- Overprovisioning is not the best solution.
- Call Admission Control (CAC) can be used.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

6. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 6
Introduction
- The offices are grouped into countries and
geographical zones.
Zone 2
Country 4
Country 3
IP network
Zone 3
PSTN
Country 5
Country 2
Country 1
Zone 1
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

7. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 7
Introduction
- Central managed system: connection of
different offices via IP, and sharing lines
between offices. Cost savings by
establishing calls from the GW of the
destination country.
Country 1
Gateway
Country 2
Gateway
PSTN
Office 2
Office 1
IP network
IP call
NTMS February 7-10, 2011. Paris
Local call
QoS and Admission Probability for a SIP-based Telephony System

8. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 8
Introduction
- Control element: Local agent (SIP proxy)
Local
agent
Gateway
Data centre
PBX
Office i
IP network
Local
agent
Local
agent
Gateway
Gateway
Office 1
NTMS February 7-10, 2011. Paris
Office 2
QoS and Admission Probability for a SIP-based Telephony System

9. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 9
Introduction
- Control element: Local agent (SIP proxy)
Local
agent
Gateway
Data centre
PBX
Office i
IP network
Local
agent
Local
agent
Gateway
Gateway
Office 1
NTMS February 7-10, 2011. Paris
Office 2
QoS and Admission Probability for a SIP-based Telephony System

10. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 10
Introduction
- SIP proxy allows the CAC to be seamlessly
integrated into the system.
- The PBX and the terminals do not have to
be modified.
- SIP Redirect messages can be used to
decrease blocking probability.
- A SIP proxy does not require a high
processing capacity.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

11. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 11
Motivation of this work
Study the system in terms of
- QoS parameters
-
OWD (One Way Delay)
Packet Loss
Jitter
R-factor
- Establishment delay
- Admission probability
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

12. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 12
R-factor
-
Defined by ITU G.107 (E-Model)
Ranges from 0 (bad quality) to 100 (good)
Acceptable for R > 70
Dependence on delay and packet loss
Widely accepted quality estimator for VoIP
services
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

13. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

14. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 14
Signaling protocols
- H.323: Used by many proprietary
solutions.
- SIP (Session Initiation Protocol): Becoming
very popular. Many open-source PBX use
it.
- SIP proxies: Used to add scalability,
transferring workload from the network core
to the borders.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

15. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 15
CAC systems
- Measurement-based: Use the state of the
network to take admission decisions
- Parameter-based: Some measurements
are carried out during system’s set up, and
a maximum number of calls is set.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

16. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 16
Buffer size and buffer policies
- «Rule of the thumb»: Bandwidth-delay
product.
- «Stanford model»: Division by sqrt(N)
(N:number of TCP flows).
- Other proposal: time-limited buffer.
Interesting for this work. Limits OWD. But
penalizes big packets.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

17. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

18. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 18
IP Telephony system
-
Offices in different countries
Dial plan only at the PBX
Internet used for VoIP traffic
The system does not use any reservation
protocol
- VoIP traffic is the only real-time one we
are going to take care of in a special way
- A parameter-based CAC is used
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

19. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 19
Local Agent
- All signaling messages pass through it
- Counts the number of calls
- In charge of admission decissions
database
IP phone
Local agent
PBX
Local agent
IP phone
INVITE
100 Trying
183 Session
Progress
rarily
480 Tempo
e
Unavailabl
Office 1
NTMS February 7-10, 2011. Paris
INVITE
100 Trying
183 Session
Progress
rarily
480 Tempo
e
Unavailabl
INVITE
raril
480 Tempo
e
Unavailabl
y
Office i
QoS and Admission Probability for a SIP-based Telephony System

20. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 20
Local Agent
- All signaling messages pass through it
- Counts the number of calls
- In charge of admission decissions
database
IP phone
Local agent
PBX
Local agent
IP phone
INVITE
100 Trying
183 Session
Progress
rarily
480 Tempo
e
Unavailabl
Office 1
NTMS February 7-10, 2011. Paris
There is no place
for this call
INVITE
100 Trying
183 Session
Progress
rarily
480 Tempo
e
Unavailabl
INVITE
raril
480 Tempo
e
Unavailabl
y
Office i
QoS and Admission Probability for a SIP-based Telephony System

21. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 21
Different call types
Type 2
IP network
Type 1
Type 6
Type 4
Type 5
Type 3
Gateway
Office 1
NTMS February 7-10, 2011. Paris
User in a country
without office
Gateway
Office 2
QoS and Admission Probability for a SIP-based Telephony System

22. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 22
Redirected calls
- Calls to PSTN can be redirected if there are
no available lines in a gateway
database
SIP proxy
PBX
Gateway
Office 1
100 Trying
183 Sessio
Progress
n
Office i
INVITE
INVITE
100 Trying
n
183 Sessio
ress
Prog
INVITE
302 Moved
ly
Temporari
database
SIP proxy
Gateway
INVITE
100 Trying
Office j
SIP proxy
IP phone
INVITE
100 Trying
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

23. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 23
Redirected calls
- Calls to PSTN can be redirected if there are
no available lines in a gateway
database
SIP proxy
PBX
Gateway
INVITE
Office 1
183 Sessio
Progress
n
There is no place
for this call
Office i
100 Trying
INVITE
100 Trying
n
183 Sessio
ress
Prog
INVITE
302 Moved
ly
Temporari
database
SIP proxy
Gateway
INVITE
100 Trying
Office j
SIP proxy
IP phone
INVITE
100 Trying
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

24. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 24
Redirected calls
- Calls to PSTN can be redirected if there are
no available lines in a gateway
database
SIP proxy
PBX
Gateway
Office 1
100 Trying
183 Sessio
Progress
n
Can it be
established from
another office?
Office i
INVITE
INVITE
100 Trying
n
183 Sessio
ress
Prog
INVITE
302 Moved
ly
Temporari
database
SIP proxy
Gateway
INVITE
100 Trying
Office j
SIP proxy
IP phone
INVITE
100 Trying
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

25. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 25
Redirected calls
- Calls to PSTN can be redirected if there are
no available lines in a gateway
database
SIP proxy
PBX
Gateway
Office 1
100 Trying
183 Sessio
Progress
n
Office i
INVITE
INVITE
100 Trying
n
183 Sessio
ress
Prog
INVITE
302 Moved
ly
Temporari
database
Try Office j
SIP proxy
Gateway
INVITE
100 Trying
Office j
SIP proxy
IP phone
INVITE
100 Trying
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

26. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 26
Redirected calls
- Calls to PSTN can be redirected if there are
no available lines in a gateway
database
SIP proxy
PBX
Gateway
Office 1
100 Trying
183 Sessio
Progress
n
Office i
INVITE
INVITE
100 Trying
n
183 Sessio
ress
Prog
INVITE
302 Moved
ly
Temporari
Accept
database
SIP proxy
Gateway
INVITE
100 Trying
Office j
SIP proxy
IP phone
INVITE
100 Trying
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

27. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

28. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 28
Testbed
- Xen Virtualization-based testbed
- Each computer is translated into a VM
- Bandwidth of office’s routers emulated
with Linux tc (Traffic Control)
- Codec used: G.729a with 2 samples per
packet
Public IP address
xenbr0
Physical
machine
Virtual network
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

29. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 29
Software tools
- Off-the-self tools:
- SIP Proxy: OpenSIPS 1.4
- PBX: Asterisk 1.6.0.1
- Softphone: PJSUA 1.0
pj
- Gateways: Emulated with PJSUA 1.0
- Admission probability: We need a bigger
scenario (Testbed has size limitations).
Matlab simulations.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

30. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

31. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 31
QoS measurements
Real Traffic in a testbed
VoIP
Offline post-processing
Buffer
policies
Network
delays
+
Dejitter
buffer
Background
Router
Traffic
Generation
Traffic
Capture
Traffic
Trace
Final
Results
- Generator: D-ITG
- Network delays and dejitter buffer effect
are added offline
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

32. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 32
Background traffic
- Size distribution
- 50% 40 bytes
- 10% 576 bytes
- 40% 1500 bytes
- Only UDP, in order to avoid flow control:
always the same background traffic.
- Different rates to saturate the access
router
- Network does not loose packets
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

33. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 33
High capacity buffer
- Step-like graphs
- When the bandiwidht is not enough, QoS
falls dramatically
1 call
5 calls
10 calls
15 calls
20 calls
R-factor
R-factor
80
75
70
400
450
500
550
600
650
700
750
800
850
900
950
1000
background traffic (kbps)
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

34. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 34
Time-limited buffer (60ms)
- The graphs present a slope
- Acceptable R values are obtained with
more background traffic
R-factor
1 call
5 calls
10 calls
15 calls
20 calls
85
R-factor
80
75
70
65
60
400
450
500
NTMS February 7-10, 2011. Paris
550
600
650
700
750
background traffic (kbps)
800
850
900
950
1000
QoS and Admission Probability for a SIP-based Telephony System

35. INTRODUCTION
RELATED WORKS
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 35
SYSTEM ARCHITECTURE
Time-limited buffer (60ms)
- Limits the maximum delay
- But increases packet loss for BG traffic
Packet loss of each traffic
RTP
45
1500 bytes
40
572 bytes
35
40 bytes
% packet loss
30
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Number of calls. Background traffic=800kbps
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

36. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 36
Time-limited buffer (60ms)
- VoIP traffic is protected because of its
small size
RTP
1500 bytes
572 bytes
40 bytes
1000
900
Bandwidth of each traffic
Bandwidth (kbps at eth level)
800
700
600
500
400
300
200
100
0
1
2
NTMS February 7-10, 2011. Paris
3
4
5
6
7
8
9
10
Number of calls. Background traffic=800kbps
11
12
13
14
15
QoS and Admission Probability for a SIP-based Telephony System

37. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 37
Time-limited buffer (60ms)
- OWD presents a limit
175
150
OWD (ms)
One Way Delay
1 call
5 calls
10 calls
15 calls
20 calls
125
100
75
400
450
500
NTMS February 7-10, 2011. Paris
550
600
650
700
750
background traffic (kbps)
800
850
900
950
1000
QoS and Admission Probability for a SIP-based Telephony System

38. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 38
Time-limited buffer (60ms)
- Packet loss grows indefinitely
6
percentage of discarded packets
Percentage of packet loss
1 call
5 calls
10 calls
15 calls
20 calls
5
4
3
2
1
0
400
450
500
550
NTMS February 7-10, 2011. Paris
600
650
700
750
background traffic (kbps)
800
850
900
950
1000
QoS and Admission Probability for a SIP-based Telephony System

39. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 39
Time-limited buffer (60ms)
- Jitter (IPDV)
1 call
5 calls
10 calls
15 calls
20 calls
10
9
IPDV
IPDV (ms)
8
7
6
5
4
3
2
400
450
500
NTMS February 7-10, 2011. Paris
550
600
650
700
750
background traffic (kbps)
800
850
900
950
1000
QoS and Admission Probability for a SIP-based Telephony System

40. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 40
Establishment delay
- Redirecting calls can increase this delay.
- Measured with simulation: From INVITE to
arrival at the destination.
- Considered delays:
-
Network delay at the LANs: Negligible
Processing time: Proxy and PBX
Queuing delay at the router
Network delay at the WAN
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

41. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 41
Establishment delay
SIP proxy
IP phone
IP phone
SIP proxy
PBX
INVITE
Office i
Proc. Proxy
Queuing
Network
INV
ITE
Office 1
Proc. PBX
Network
INV
ITE
Proc. Proxy
Queuing
M
302
ove
d
Processing delays
Network
Network
INV
ITE
Proc. Proxy
INVITE
NTMS February 7-10, 2011. Paris
Office j
Proc. PBX
QoS and Admission Probability for a SIP-based Telephony System

42. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 42
Establishment delay
SIP proxy
IP phone
IP phone
SIP proxy
PBX
INVITE
Office i
Proc. Proxy
Queuing
Network
INV
ITE
Office 1
Proc. PBX
Network
INV
ITE
Proc. Proxy
Queuing
M
302
ove
d
Queuing delays
Network
Network
INV
ITE
Proc. Proxy
INVITE
NTMS February 7-10, 2011. Paris
Office j
Proc. PBX
QoS and Admission Probability for a SIP-based Telephony System

43. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 43
Establishment delay
SIP proxy
IP phone
IP phone
SIP proxy
PBX
INVITE
Office i
Proc. Proxy
Queuing
Network
INV
ITE
Office 1
Proc. PBX
Network
INV
ITE
Proc. Proxy
Queuing
M
302
ove
d
WAN delays
Network
Network
INV
ITE
Proc. Proxy
INVITE
NTMS February 7-10, 2011. Paris
Office j
Proc. PBX
QoS and Admission Probability for a SIP-based Telephony System

44. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 44
Establishment delay
- Different RTT values
- Independent of the number of offices
2 offices
4 offices
6 offices
8 offices
Establishment delay
350
Establishment delay (ms)
300
250
200
150
100
50
25
50
75
100
125
RTT (ms)
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

45. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 45
Admission probability
-
Matlab simulations
Each office has 25 users
Gateways have 6 lines
CAC limit=6 (variable in some tests)
Different values of and number of offices
...
...
M2
IP network
AI21
AP2
N2
...
...
PSTN
...
N1
M1
...
AI12
AP1
AO1
Office 1
NTMS February 7-10, 2011. Paris
PSTN
AO2
Office 2
QoS and Admission Probability for a SIP-based Telephony System

46. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 46
Admission probability
Admission probability
3 offices
5 offices
7 offices
10 offices
15 offices
Percentage of admitted conferences (%)
100
95
90
85
80
3
NTMS February 7-10, 2011. Paris
3,5
4
4,5
λ (conferences per hour per user)
5
QoS and Admission Probability for a SIP-based Telephony System

47. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 47
Admission probability
Admission probability
3 offices
5 offices
7 offices
10 offices
15 offices
Percentage of admitted conferences (%)
100
95
90
Increasing the number of offices is beneficial
85
80
3
NTMS February 7-10, 2011. Paris
3,5
4
4,5
λ (conferences per hour per user)
5
QoS and Admission Probability for a SIP-based Telephony System

48. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 48
Admission probability
- Influence of CAC limit
2 offices and isolated mode
2 offices and sharing mode
4 offices and isolated mode
4 offices and sharing mode
6 offices and isolated mode
6 offices and sharing mode
100
Admission probability
Admission probability (%)
95
90
85
80
1
2
3
NTMS February 7-10, 2011. Paris
4
5
6
7
CAC limit
8
9
10
11
12
13
QoS and Admission Probability for a SIP-based Telephony System

49. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 49
Admission probability
- Influence of CAC limit
2 offices and isolated mode
2 offices and sharing mode
4 offices and isolated mode
4 offices and sharing mode
6 offices and isolated mode
6 offices and sharing mode
100
Admission probability
Sharing mode is better than isolated mode
Admission probability (%)
95
90
85
80
1
2
3
NTMS February 7-10, 2011. Paris
4
5
6
7
CAC limit
8
9
10
11
12
13
QoS and Admission Probability for a SIP-based Telephony System

50. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 50
Admission probability
- Influence of CAC limit
2 offices and isolated mode
2 offices and sharing mode
4 offices and isolated mode
4 offices and sharing mode
6 offices and isolated mode
6 offices and sharing mode
100
Admission probability
Increasing the number of offices is beneficial
Admission probability (%)
95
90
85
80
1
2
3
NTMS February 7-10, 2011. Paris
4
5
6
7
CAC limit
8
9
10
11
12
13
QoS and Admission Probability for a SIP-based Telephony System

51. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 51
Admission probability
- Influence of CAC limit
2 offices and isolated mode
2 offices and sharing mode
4 offices and isolated mode
4 offices and sharing mode
6 offices and isolated mode
6 offices and sharing mode
100
Admission probability
In Sharing mode, the increase of CAC limit
improves the Asmission probability
Admission probability (%)
95
90
85
80
1
2
3
NTMS February 7-10, 2011. Paris
4
5
6
7
CAC limit
8
9
10
11
12
13
QoS and Admission Probability for a SIP-based Telephony System

52. Index
INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION
TESTS AND RESULTS
CONCLUSIONS

53. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 53
Conclusions
- A SIP-based IP telephony system has been
designed and tested.
- SIP proxies are used in order to implement
a CAC.
- QoS measurements show the better
performance of a time-limited buffer.
- Establishment delay does not depend on
the number of offices.
- Sharing the gateways improves admission.
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

54. Presentación
Jose Saldana
Jenifer Murillo
Julián Fernández Navajas
G RUPO DE
T ECNOLOGÍAS DE LAS
COMUNICACIONES
CPS - University of Zaragoza, Spain
José Ruiz Mas
Eduardo Viruete Navarro
José I. Aznar

55. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 55
Xen Virtualization
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System

56. INTRODUCTION
RELATED WORKS
SYSTEM ARCHITECTURE
SYSTEM IMPLEMENTATION RESULTS CONCLUSIONS 56
PJSUA interface
NTMS February 7-10, 2011. Paris
QoS and Admission Probability for a SIP-based Telephony System