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Performance Evaluation of IP Performance Evaluation of IP Telephony Telephony
over University Networkover University Network
A project funded by University Fast Track
ByM. Kousa, M Sait, A. Shafi, A. Khan
King Fahd Univ. of Petroleum & Minerals (KFUPM)
Dhahran, Saudi Arabia.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 22
Presentation OutlinesPresentation Outlines
Definition of VoIP. Performance and Quality Indicators. University Networks Assessment Designs. LAN Assessment Results Wi-FI Assessment Results. ADSL Assessment Results Conclusions.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 33
What is IPTWhat is IPT
Special telephone sets connected directly to a network port (RJ45)
Carrying voice traffic over the data network.
Circuit-Switched versus Packet-switched
Enabler: VoIP protocols.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 44
Performance and Quality IndicatorsPerformance and Quality Indicators Delay (or Latency): Time takes a packet to
make its way through a network end-to-end. Packet Loss: Due to errors in Header of
Buffer overflow. Jitter: The measure of the variation of
packet arrival time. Mean Opinion Square (MOS): The most
well-known measure of voice quality. MOS (Lower Limit) User Satisfaction
4.34 Very satisfied 4.03 Satisfied 3.60 Some users dissatisfied 3.10 Many users dissatisfied 2.58 Nearly all users dissatisfied
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 55
Coding and Compression AlgorithmsCoding and Compression Algorithms
Co
de
c
De
fau
lt D
ata
Ra
te
(kb
ps
)
Pa
ck
eti
zati
on
D
ela
y
Th
eo
reti
ca
l M
ax
imu
m M
OS
G.711u; G.711a 64 1.0 ms 4.40
G.723.1 ACELP 5.3 67.5 ms 3.69
The process of converting Analog voice signals to digital data signals is done with a coder-decoder (CODEC).
codec selection depends on bandwidth and quality.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 66
University NetworksUniversity Networks
Bldg . 3 Bldg . 4 Bldg . 5 Bldg . 6 Bldg . 24Bldg . 23Bldg . 22Bldg . 21Bldg . 20Bldg . 19Bldg . 17Bldg . 16Bldg . 15Bldg . 11Bldg . 10Bldg . 9Bldg . 8Bldg . 7
Bldg . 14
ITC
Bldg. 29 Bldg
. 45
Bld
g.
36
Bldg . 14
ITC
North Gate
Main Gate
Bldg 40
Press
Clinic
Tel . Exch
ELC
Bldg . 28
Schools
Tel . Exch
Bldg 53
Bldg 54
Bldg 34
ERL
Faculty Housing
DCC Internet(Awalnet)
ATM
Currently 4 Mbps
Voice over IP (VoIP) assessment is performed for all four kinds of university networks.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 77
University Academic Buildings considered for LAN University Academic Buildings considered for LAN Assessment Test DesignAssessment Test Design
List of University Academic Buildings, considered for VoIP Test
S. No.
Building Number
Reason Approx. No. of Telephone
Users 1 14 Core data network 250
2 34 Core voice network 35 3 21 Largest office building have the
highest number of telephone users and highest expected number of incoming and outgoing calls
700
4 5 Tallest academic building and situated on the edge of wireless connection to DCC.
100
5 55 Building with highest number of intermediate routers and home to telephone operators
65
6 59 Largest academic building 300
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 88
University LAN Assessment Test DesignUniversity LAN Assessment Test Design
LAN Assessment Physical Connectivity Diagram
B-34
B-55Tel . Exch
B-21
B-59BackboneNetwork
B-5
B-141000-Base LX
Uplink
Distribution LayerUTIL
STAT
DUPLX
SPEED
SYSTEM
RPSMODE
CATALYST 3550
1 2 3 4 5 6 7 8 9 10
11
12
UTILSTAT
DUPLEXSPEED
SYSTEMRPS
CATALYST 35503
4
5
6
7
8
9
10
11
12
1
2
15
16
17
18
19
20
21
22
23
24
13
14
1 2
Layer-3 Switch
Layer-2 Switch
1000
-Bas
e T
U
plin
k
1000-Base LX Uplink
Computer
Laptop
Access Layer
100-Base T
Inside a Building
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 99
University LAN Assessment Test DesignUniversity LAN Assessment Test Design
LAN Assessment Logical Connectivity Diagram
B-5
B-55B-59
B-14
B-34B-21
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1010
University LAN Assessment Test DesignUniversity LAN Assessment Test Design
Worst-case scenario: half of the telephone users are busy on calls.
Calls originating from any building are distributed to all other buildings according to their user intensity.
Figure shows concurrent number of calls between any two buildings.
All calls are assumed to last for 3 minutes, while the inter-call delay for the calls on the same link was set to 5 minutes.
B-14B-5
B-21
B-59 B-55
B-34
3
11
22
91
4
2
9
26
3
1
16
3Calls=7
Calls=37Calls=18
Calls=13
Calls=66
Calls=43
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1111
LAN Assessment ResultsLAN Assessment Results
Call Quality Summary- G723
Acceptable100%
Good0%
Poor< 1%Unavailable
< 1%
Good
Acceptable
Poor
Unavailable
Call Quality Summary- G711
Good100%
Acceptable0%
Poor< 1%
Unavailable< 1%
Good
Acceptable
Poor
Unavailable
Number of VoIP Probes 6
Number of links 15
Total number of concurrent calls emulated in the test
92
Schedule Duration of Test 5 days
Total number of calls emulated in the test 93748
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1212
LAN Assessment ResultsLAN Assessment ResultsMOS ResultsMOS Results
Call Quality Summary by Call Codec
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 4.38 3.65
G.711u (64 kbps) G.723.1-ACELP (5.3 kbps)
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1313
University LAN UtilizationUniversity LAN Utilization
Building 21 LAN Utilization for a Year 2007-08
Building 14 LAN Utilization for a Year 2007-08
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1414
University Wireless LAN (WiFi)University Wireless LAN (WiFi)
•IEEE 802.11g standard which supports up to 54 Mbps.• The wireless access points are back connected to the layer-2 switches• Layer-2 switches are connected to the building layer-3 switch.• Layer-3 switch forwards the data over the fiber-optic link to the university core network.
Distribution Layer
Layer-3 Switch
Layer-2 PoE Switch
Access Layer
UTIL
STAT
DUPLX
SPEED
SYSTEM
RPS
MODE
CATALYST 3550
1 2 3 4 5 6 7 8 9 10
11
12
SYST RPS
STRT DUPLXSPEEDUTIL
MODE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Catalyst 2950SERIES10Base-T/100Base-TX
LaptopLaptop
Access Point
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
LaptopLaptop
Access Point
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
Distribution Layer
Layer-3 Switch
Layer-2 PoE Switch
Access Layer
UTIL
STAT
DUPLX
SPEED
SYSTEM
RPS
MODE
CATALYST 3550
1 2 3 4 5 6 7 8 9 10
11
12
SYST RPS
STRT DUPLXSPEEDUTIL
MODE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Catalyst 2950SERIES10Base-T/100Base-TX
LaptopLaptop
Access Point
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
BackboneNetwork
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1515
WiFi Assessment Tests Design, WiFi Assessment Tests Design, Physical Connectivity (Bldg 59)Physical Connectivity (Bldg 59)
Room 0032 (very good signal)Room 0072 – PC1 (good signal)Room 0072 – PC2 (good signal, Linked with same AP as of PC1)Room 0081 (far from AP, poor signal)Room 1079 (far from AP, poor signal)Room 2078 (Excellent signal)
Distribution LayerLayer-3 Switch
Layer-2 PoE Switch
Access Layer
UTIL
STAT
DUPLX
SPEED
SYSTEM
RPS
MODE
CATALYST 3550
1 2 3 4 5 6 7 8 9 10
11
12
AP1
SYST RPS
STRT DUPLXSPEEDUTIL
MODE
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Catalyst 2950SERIES10Base-T/100Base-TX
R-0032
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
R-2078
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
R-0071-PC2
R-1079
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
R-0071-PC1
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
R-0081
CISCO AIRONET 1100 SERIES
WIRELESS ACCESS POINT
AP2
AP3
AP4
AP5
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1616
WiFi Assessment Tests Design, WiFi Assessment Tests Design, Logical ConnectivityLogical Connectivity
Three levels of traffic intensity
Low: one call is initiated between any pair Medium: 2 simultaneous calls are initiated between any pair High: 4 simultaneous calls are initiated between any pair.
R-2078
R-0071-PC1
R-0081
R-0071-PC2
R-0032
R-1079
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1717
WiFi Assessment Results WiFi Assessment Results G711 – 1 CallG711 – 1 Call
The performance seems to be pretty good for more than 99% of the calls. The average delay was always below 45 ms, which is quite acceptable. The lost data was negligible (less than 0.03%).
Number of Node 6
Number of Links 15
Number of concurrent calls between any two nodes 1
Number of concurrent calls per node 5 x 1 = 5
Total number of concurrent calls emulated in the test 15 x 1 = 15
Schedule Duration of Test 1 day
Total number of calls emulated in the test 2700
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1818
WiFi Assessment Results WiFi Assessment Results G711 – 2 Calls: Call Quality (MOS)G711 – 2 Calls: Call Quality (MOS)
Number of VoIP Probes 6
Number of Links 15
Number of concurrent calls between any two VoIP probes 2
Number of concurrent calls per VoIP probe 5 x 2 = 10
Total number of concurrent calls emulated in the test 15 x 2 = 30
Schedule Duration of Test 1 day
Total number of calls emulated in the test 5400
Call Quality Summary
Good67%
Poor33%
Acceptable< 1%
Unavailable< 1%
Good
Acceptable
Poor
Unavailable
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 1919
WiFi Assessment Results WiFi Assessment Results G711 – 2 Calls: Factors Affecting MOSG711 – 2 Calls: Factors Affecting MOS
The percentage effect of each of the other three factors; delay, jitter, lost data, is shown in figure. The source of poor quality is mainly due to delay (51%) and lost data (41%). The effect of jitter is much smaller (8%). Factors Affecting Call Quality
Delay51%
Jitter8%
Lost Data41%
Delay
Jitter
Lost Data
Codec
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2020
WiFi: G711 – 2 Calls: Call Quality by Call GroupWiFi: G711 – 2 Calls: Call Quality by Call Group
Call Quality Summary by Call Group - Bottom 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 1.30 1.31 1.32 1.32 1.35
59-0032-59-0081 : G.711u (64 kbps)
59-1079-59-0081 : G.711u (64 kbps)
59-0081-59-0071-P C1 : G.711u (64
kbps)
59-0071-P C2-59-0081 : G.711u (64
kbps)
59-0081-59-2078 : G.711u (64 kbps)
Call Quality Summary by Call Group - Top 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 4.38 4.38 4.38 4.38 4.38
59-0071-P C1-59-0071-P C2 : G.711u
(64 kbps)
59-0071-P C1-59-0032 : G.711u (64
kbps)
59-0071-P C2-59-0032 : G.711u (64
kbps)
59-0071-P C1-59-2078 : G.711u (64
kbps)
59-0071-P C2-59-2078 : G.711u (64
kbps)
Room 0081 and its AP is the source of trouble. All communications between 0081 and other nodes are poor, and they are the only poor links.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2121
WiFi: G711 – 2 Calls: DelayWiFi: G711 – 2 Calls: Delay
The delay varies between 300 and 310 ms, which is on the high side.
Delay Evaluation by Hour
0%
20%
40%
60%
80%
100%
294
298
302
306
310
314
Del
ay (
ms)
Good 67 67 67 67 67 67 67 67 67 65 67 67 67 67 67 67 67 67 67 67 67 67 67 67
Acceptable 0%0% 0% 0% 0% 0% 0%0% 0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0% 0%0% 0% 0%
P oor 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33
Unavailable 0%0% 0% 0% 0% 0% 0%0% 0% 3% 0% 0%0% 0% 0% 0%0% 0% 0% 0% 0%0% 0% 0%
Delay (ms) 301301301301304302301302308310306303303302302303303300301301301301301301
12 AM
1 AM
2 AM
3 AM
4 AM
5 AM
6 AM
7 AM
8 AM
9 AM
10 AM
11 AM
12 PM
1 PM
2 PM
3 PM
4 PM
5 PM
6 PM
7 PM
8 PM
9 PM
10 PM
11 PM
Room 0081 and its AP is the source of trouble. The delay on those pairs where this link is involved exceeds 800 ms, while the delay on other groups are very low (45 m sec).
Delay Summary by Call Group
0
100
200
300
400
500
600
700
800
900
Del
ay (
ms)
Delay (ms) 826 818 814 812 812 49 47 46 46 45
59-0032-59-0081 : G.711u
59-0071-P C2-59-
0081 :
59-1079-59-0081 : G.711u
59-0081-59-2078 : G.711u
59-0081-59-0071-
P C1 :
59-0032-59-1079 : G.711u
59-0071-P C2-59-
0032 :
59-0032-59-2078 : G.711u
59-0071-P C1-59-0032 :
59-0071-P C1-59-1079 :
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2222
On those poor groups the lost data exceeds 20%
Lost Data Evaluation by Hour
0%
20%
40%
60%
80%
100%
5.79%
6.29%
6.79%
7.29%
7.79%
8.29%
Lo
st D
ata
(%)
Good 63 67 67 67 67 67 67 67 67 62 67 67 67 67 67 67 67 67 67 67 67 67 67 67
Acceptable 4%0% 0%0%0% 0% 0%0%0%0% 0% 0%0%0%0% 0% 0%0% 0% 0%0% 0%0% 0%
P oor 33 33 33 33 33 33 33 33 33 36 33 33 33 33 33 33 33 33 33 33 33 33 33 33
Unavailable 0%0% 0%0%0% 0% 0%0%0%3% 0% 0%0%0%0% 0% 0%0% 0% 0%0% 0%0% 0%
Lost Data 6.6 6.6 6.66.6 7.2 6.7 6.7 6.97.6 7.2 7.7 7.2 7.37.1 7.0 7.0 6.96.8 6.6 6.6 6.7 6.66.6 6.5
12 AM
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7 AM
8 AM
9 AM
10 AM
11 AM
12 PM
1 PM
2 PM
3 PM
4 PM
5 PM
6 PM
7 PM
8 PM
9 PM
10 PM
11 PM
The lost data varies between 6.6% and 7.7%. In both plots, the high values are noticed in the hours 8:00 – 10:00 AM, indicating a slightly more traffic activity of the WiFi network at this period.
WiFi: G711 – 2 Calls: Lost DataWiFi: G711 – 2 Calls: Lost Data
Lost Data Summary by Call Group
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
Lo
st D
ata
(%)
Lost Data 22.36% 21.74% 21.19% 20.48% 18.10% 0.03% 0.03% 0.03% 0.02% 0.01%
59-0032-59-0081 : G.711u
59-1079-59-0081 : G.711u
59-0081-59-0071-
P C1 :
59-0071-P C2-59-
0081 :
59-0081-59-2078 : G.711u
59-0032-59-1079 : G.711u
59-2078-59-1079 : G.711u
59-0071-P C2-59-
1079 :
59-0071-P C1-59-1079 :
59-0032-59-2078 : G.711u
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2323
For the first group the quality is maintained well throughout the call duration, while the quality is poor throughout the duration of second call, with short intervals when the communication is lost.
Zooming in to the call level, the figure shows three random calls for a good group, while second figure shows three random calls for a poor group.
WiFi: G711 – 2 Calls: Sample Call QualityWiFi: G711 – 2 Calls: Sample Call Quality
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2424
WiFi Assessment Results WiFi Assessment Results G711 – 4 Calls: Call Quality (MOS)G711 – 4 Calls: Call Quality (MOS)
Figure shows the overall statistics of call quality. The Figure shows that the call quality is poor most of the time (75%). The quality is acceptable for 14% of the time, and good for 10% of the time.
Number of nodes 6
Number of Links 15
Number of concurrent calls between any two nodes 4
Number of concurrent calls per node 5 x 4 = 20
Total number of concurrent calls emulated in the test 15 x 4 = 60
Schedule Duration of Test 1 day
Total number of calls emulated in the test 10800
Call Quality Summary
Good10%
Acceptable14%
Poor75%
Unavailable1%
Good
Acceptable
Poor
Unavailable
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2525
WiFi Assessment Results WiFi Assessment Results G711 – 4 Calls: Factors Affecting MOSG711 – 4 Calls: Factors Affecting MOS
The percentage effect of the three performance factors is shown in Figure below. Here we can clearly see that the source of poor quality is lost data (52 %) and delay (44%). The effect of jitter is marginal (4%) therefore no further analysis of jitter is carried out.
Factors Affecting Call Quality
Delay44%
Jitter4%
Lost Data52%
Delay
Jitter
Lost Data
Codec
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2626
WiFi: G711 – 4 Calls: Call Quality by Call GroupWiFi: G711 – 4 Calls: Call Quality by Call Group
Call Quality Summary by Call Group - Top 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 3.98 3.89 3.55 3.25 2.96
59-0032-59-2078 : G.711u (64 kbps)
59-2078-59-1079 : G.711u (64 kbps)
59-0032-59-1079 : G.711u (64 kbps)
59-0071-P C2-59-2078 : G.711u (64
kbps)
59-0071-P C2-59-0032 : G.711u (64
kbps)
Call Quality Summary by Call Group - Bottom 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 1.20 1.20 1.16 1.04 1.03
59-0032-59-0081 : G.711u (64 kbps)
59-0081-59-2078 : G.711u (64 kbps)
59-1079-59-0081 : G.711u (64 kbps)
59-0081-59-0071-P C1 : G.711u (64
kbps)
59-0071-P C2-59-0081 : G.711u (64
kbps)
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2727
WiFi: G711 – 4 Calls: Call Quality by HourWiFi: G711 – 4 Calls: Call Quality by Hour
The Figure shows the effect of the data traffic on the quality of IPT traffic (MOS ~ 2.7 in light traffic hours 11 pm – 7 am) (MOS ~ 2.1 in Busy Hour (BH) 8am – 9 pm)
Call Quality Evaluation by Hour
0%
20%
40%
60%
80%
100%
1.00
1.70
2.40
3.10
3.80
4.50
MO
S
Good 6% 12%8% 18%14%11%21%23%8% 11%10%10%3% 9% 7% 7% 5% 9% 5% 8% 8% 7% 11% 11%
Acceptable 23%21%20%22%27%20%22%22%13%6% 8% 9% 11% 9% 9% 10%12%7% 10%11% 9% 11%14%22%
P oor 70%66%70%59%59%69%57%55%78%82%81%79%86%83%85%78%83%84%86%81%82%79%74%66%
Unavailable 1% 1% 2% 1% 1% 0% 0% 0% 1% 0% 1% 2% 0% 0% 0% 6% 1% 1% 0% 0% 2% 3% 0% 0%
M OS 2.6 2.7 2.6 2.8 2.8 2.7 2.8 2.8 2.3 2.132.16 2.2 2.0 2.172.13 2.112.122.13 2.0 2.10 2.112.12 2.4 2.71
12 AM
1 AM
2 AM
3 AM
4 AM
5 AM
6 AM
7 AM
8 AM
9 AM
10 AM
11 AM
12 PM
1 PM
2 PM
3 PM
4 PM
5 PM
6 PM
7 PM
8 PM
9 PM
10 PM
11 PM
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2828
WiFi: G711 – 4 Calls: Delay by HourWiFi: G711 – 4 Calls: Delay by Hour
Figure shows that the delay has been always excessive (average delay over 600 ms and in busy hours it even approaches 740 ms).
Delay Evaluation by Hour
0%
20%
40%
60%
80%
100%
0
160
320
480
640
800
Del
ay (
ms)
Good 28 33 27 38 33 25 43 43 26 29 27 30 17%25 20 19%18% 25 16%23 22 20 28 33
Acceptable 36 31% 35 28 32 42 22 22 31%17%23 24 36 30 33 25 30 25 31%25 24 27 30 31%
P oor 35 34 36 34 34 33 36 35 43 54 49 44 47 45 47 50 51% 50 53 52 53 50 43 36
Unavailable 1% 1% 2% 1% 1% 0% 0% 0% 1% 0% 1% 2% 0% 0% 0% 6% 1% 1% 0% 0% 2% 3% 0% 0%
Delay (ms) 637625655608617642615601653720687666697673690731721697717729733724678630
12 AM
1 AM
2 AM
3 AM
4 AM
5 AM
6 AM
7 AM
8 AM
9 AM
10 AM
11 AM
12 PM
1 PM
2 PM
3 PM
4 PM
5 PM
6 PM
7 PM
8 PM
9 PM
10 PM
11 PM
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 2929
WiFi: G711 – 4 Calls: Lost Data of Best and Worst Call by HourWiFi: G711 – 4 Calls: Lost Data of Best and Worst Call by Hour
The figure shows the lost data evaluation, the average percentage of lost data has been above 16%, and exceeding 28% during Busy hours.
Lost Data Evaluation by Hour
0%
20%
40%
60%
80%
100%
0.00%
7.00%
14.00%
21.00%
28.00%
35.00%
Lo
st D
ata
(%)
Good 0% 2%0% 1% 1% 1% 2% 5%2% 3%5% 2% 0%5% 1% 1% 3%4% 1% 1% 2%1% 0%0%
Acceptable 0% 0%0% 1% 1% 1% 1% 1% 1% 2%0% 1% 1% 1% 3%3% 2%1% 1% 2% 2%2% 1% 0%
P oor 99 97 98 97 96 97 97 95 96 95 94 95 99 94 96 90 95 94 99 97 94 94 99 100
Unavailable 1% 1% 2% 1% 1% 0%0% 0%1% 0%1% 2% 0%0% 0%6% 1% 1% 0%0% 2%3% 0%0%
Lost Data 19. 18. 18. 17. 17. 17. 16. 16. 25. 27.28. 26. 29.27. 28.28. 28.28. 28.26. 27.27. 21. 18.
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11 PM
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3030
WiFi: G711 – 4 Calls: Sample Call QualityWiFi: G711 – 4 Calls: Sample Call Quality
Finally, we show through-call evaluation of Call Quality and corresponding Lost Data of some selected calls on the best link. Two such calls are depicted in figures.
It is interesting to show that while a high MOS is maintained throughout the call duration there are intermittent periods when call quality drops to a poor level. These are the periods when the link suffers from large packet loss.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3131
WiFi Assessment Results WiFi Assessment Results G723 – 1 Call: Call Quality (MOS)G723 – 1 Call: Call Quality (MOS)
The performance is always acceptable. It should be noted that “acceptable” is the best quality that can be obtained for G723.
Call Quality Summary
Acceptable100%
Poor< 1%
Unavailable< 1%
Good
Acceptable
Poor
Unavailable
Number of nodes 6
Number of Links 15
Number of concurrent calls between any two nodes 1
Number of concurrent calls per node 5 x 1 = 5
Total number of concurrent calls emulated in the test 15 x 1 = 15
Schedule Duration of Test 1 day
Total number of calls emulated in the test 2700
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3232
WiFi Assessment Results WiFi Assessment Results G723 – 1 Call: Factors Affecting MOSG723 – 1 Call: Factors Affecting MOS
Therefore, that “acceptability” of the quality of the IPT call is mainly due to codec. The average delay is in the range of 130 ms. This is higher that the average delay for the G711 codec under same traffic load, due to the extra processing time for compression.
Factors Affecting Call Quality
Codec93%
Delay7%
Jitter< 1%
Lost Data< 1%
Delay
Jitter
Lost Data
Codec
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3333
WiFi Assessment Results WiFi Assessment Results G723 – 4 Calls: Call Quality (MOS)G723 – 4 Calls: Call Quality (MOS)
By increasing the number of calls to 4 between each pair, the quality gets severely affected. Figure shows that only 28% of the calls are now acceptable.
Number of nodes 6
Number of Links 15
Number of concurrent calls between any two nodes 4
Number of concurrent calls per nodes 5 x 4 = 20
Total number of concurrent calls emulated in the test 15 x 4 = 60
Schedule Duration of Test 1 day
Total number of calls emulated in the test 10800
Call Quality Summary
Acceptable28%
Poor72%
Unavailable< 1%
Good
Acceptable
Poor
Unavailable
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3434
WiFi: G723 – 4 Calls: Call Quality by Call GroupWiFi: G723 – 4 Calls: Call Quality by Call Group
The pattern of variation of performance between groups is very much similar to the 2-call case of G-711.
Call Quality Summary by Call Group - Top 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 3.60 3.59 3.59 3.58 3.56
59-0071-P C2-59-2078 : G.723.1-
ACELP (5.3 kbps)
59-0071-P C2-59-1079 : G.723.1-
ACELP (5.3 kbps)
59-0071-P C1-59-2078 : G.723.1-
ACELP (5.3 kbps)
59-0071-P C1-59-1079 : G.723.1-
ACELP (5.3 kbps)
59-2078-59-1079 : G.723.1-ACELP
(5.3 kbps)
Call Quality Summary by Call Group - Bottom 5
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
MOS 1.28 1.33 1.36 1.38 1.45
59-0032-59-0081 : G.723.1-ACELP
(5.3 kbps)
59-1079-59-0081 : G.723.1-ACELP
(5.3 kbps)
59-0071-P C2-59-0081 : G.723.1-
ACELP (5.3 kbps)
59-0071-P C1-59-0081 : G.723.1-
ACELP (5.3 kbps)
59-0081-59-2078 : G.723.1-ACELP
(5.3 kbps)
Namely, the groups are classified in two sets; always acceptable (MOS=3.6), and always poor (MOS=1.4).
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3535
WiFi: G723 – 4 Calls: Call Quality of Best and Worst Group by HourWiFi: G723 – 4 Calls: Call Quality of Best and Worst Group by Hour
Since data rate of G723 is low, there does not seem to be a Busy Hour effect on the MOS for either set.
Call Quality Evaluation by Hour
0%
20%
40%
60%
80%
100%
1.00
1.70
2.40
3.10
3.80
4.50
MO
S
Good 0%0% 0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0%0% 0% 0%
Acceptable 63 71%78 71%56 71%50 82 69 79 81%75 75 71%59 71%69 75 84 29 69 71% 78 79
P oor 38 29 22 29 44 29 50 11%31%21%19%25 25 29 41%29 31% 25 16%71%31%29 22 21%
Unavailable 0%0% 0% 0% 0% 0%0% 7% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0%0% 0% 0%
MOS 3.6 3.53.613.5 3.6 3.6 3.5 3.6 3.613.6 3.6 3.6 3.53.613.5 3.5 3.5 3.6 3.6 3.5 3.6 3.5 3.613.6
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Call Quality Evaluation by Hour
0%
20%
40%
60%
80%
100%
1.00
1.70
2.40
3.10
3.80
4.50
MO
S
Good 0%0% 0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0%0% 0% 0%
Acceptable 0%0% 0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0%0% 0% 0%
P oor 100100100 100100100100100 100100100100 100100100100100 100100100100100 100 86
Unavailable 0%0% 0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0% 0%0% 0% 0%0% 0%14%
MOS 1.161.151.241.271.291.481.261.241.231.281.291.351.371.261.251.241.251.341.281.261.251.381.281.23
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EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3636
The call quality within the duration of the call is maintained almost constant, for "acceptable groups" as well as poor groups.
WiFi: G723 – 4 Calls: Call Inside DetailsWiFi: G723 – 4 Calls: Call Inside Details
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3737
University ADSL NetworkUniversity ADSL Network
ADSL service provided on campus is at G-Lite rate (1.5 Mbps downlink and 0.5 Mbps uplink).
The ADSL system of university is of modular nature. There are total of 10 DSLAMs and each DSLAM has a capacity of approximately 100 ADSL lines. Each DSLAM uplink supports 100 Mbps and is connected to the layer-2 switch.
LAN
UTILSTAT
DUPLEXSPEED
SYSTEMRPS
CATALYST 35503
4
5
6
7
8
9
10
11
12
1
2
15
16
17
18
19
20
21
22
23
24
13
14
1 2
DSLAM 1
Layer-2 Switch
Computer
DSLAM 2 DSLAM 3
Computer Computer Computer Computer Computer Computer
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3838
University ADSL Assessment DesignUniversity ADSL Assessment Design
LAN
UTILSTAT
DUPLEXSPEED
SYSTEMRPS
CATALYST 35503
4
5
6
7
8
9
10
11
12
1
2
15
16
17
18
19
20
21
22
23
24
13
14
1 2
DSLAM 1
Layer-2 Switch
DSLAM 1-1
DSLAM 8
DSLAM 1-2 DSLAM 1-3 DSLAM 8-1
DSLAM 8-2
Local Loop
Local Loop
Local Loop
DSLAM 1-1
DSLAM 1-2 DSLAM 1-3
DSLAM 8-1 DSLAM 8-2
ADSL Assessment Test Physical Connectivity
ADSL Assessment Test Logical Connectivity
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 3939
ADSL Assessment ResultsADSL Assessment Results
ADSL Assessment Parameters used for VoIP Test
For G711 codec: 100% good result, Delay < 62 ms, Jitter and Lost Data almost negligible.
For G723 codec: Similar results, slightly lower MOS and higher delay.
Number of nodes 5
Number of Links 10
Number of concurrent calls between any two nodes 1
Number of concurrent calls per node 4 x 1 = 4
Total number of concurrent calls emulated in the test 10 x 1 = 10
Schedule Duration of Test 1 day
Total number of calls emulated in the test 1800
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4040
ADSL Assessment ResultsADSL Assessment ResultsCall Quality (MOS) for G711Call Quality (MOS) for G711
Call Quality Summary
Good100%
Good
Acceptable
Poor
Unavailable
Call Quality Evaluation by Hour
0%
20%
40%
60%
80%
100%
1.00
1.70
2.40
3.10
3.80
4.50
MO
S
Good 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Acceptable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
M OS 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3 4.3
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11 PM
Call Quality Summary by Call Group
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
M OS 4.38 4.37 4.37 4.37 4.37 4.37 4.37 4.37 4.37 4.37
DSLAM 1-2-
DSLAM 8-1 :
DSLAM 1-3-
DSLAM 8-1 :
DSLAM 1-2-
DSLAM 8-2 :
DSLAM 1-1-
DSLAM 1-2 :
DSLAM 8-2-
DSLAM 1-3 :
DSLAM 1-1-
DSLAM 8-1 :
DSLAM 1-2-
DSLAM 1-3 :
DSLAM 1-1-
DSLAM 1-3 :
DSLAM 1-1-
DSLAM 8-2 :
DSLAM 8-1-
DSLAM 8-2 :
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4141
ADSL Assessment ADSL Assessment ResultsResults
Delay and Lost Data Delay and Lost Data for G711for G711
Delay Evaluation by Hour
0%
20%
40%
60%
80%
100%
59
60
61
62
63
64
Del
ay (
ms)
Good 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Acceptable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Delay (ms) 61 62 61 61 61 62 60 61 61 60 60 62 61 61 61 61 62 62 61 62 61 61 61 61
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Lost Data Evaluation by Hour
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100%
0.00%
0.01%
0.02%
0.03%
0.04%
0.05%
Lo
st D
ata
(%)
Good 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Acceptable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Lost Data .01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.02 .03 .03 .03 .04 .04 .02 .01%.01%.01%.01%.01%.01%.01%
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EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4242
ADSL Assessment ResultsADSL Assessment ResultsCall Quality (MOS) for G723Call Quality (MOS) for G723
Call Quality Summary
Acceptable99%
Poor1%
Unavailable< 1%
Good
Acceptable
Poor
Unavailable
Factors Affecting Call QualityDelay9%
Codec91%
Jitter< 1%
Lost Data< 1%
Delay
Jitter
Lost Data
Codec
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4343
ADSL Assessment ADSL Assessment ResultsResults
Call Quality (MOS) by Call Quality (MOS) by Hour and by Group, Hour and by Group,
for G723for G723
Call Quality Evaluation by Hour
0%
20%
40%
60%
80%
100%
1.00
1.70
2.40
3.10
3.80
4.50
MO
S
Good 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Acceptable 100 100 100 100 100 100 100 100 100 100 100 100 96%97%95%100 99%100 100 87%98%100 100 100
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 4% 3% 0% 0% 1% 0% 0% 13%3% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 5% 0% 0% 0% 0% 0% 0% 0% 0% 0%
M OS 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6
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Call Quality Summary by Call Group
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
MO
S
M OS 3.63 3.63 3.62 3.62 3.62 3.62 3.62 3.62 3.62 3.62
DSLAM 1-2-
DSLAM 8-2 :
DSLAM 1-2-
DSLAM 8-1 :
DSLAM 8-2-
DSLAM 1-3 :
DSLAM 1-1-
DSLAM 1-3 :
DSLAM 1-3-
DSLAM 8-1 :
DSLAM 1-1-
DSLAM 1-2 :
DSLAM 1-2-
DSLAM 1-3 :
DSLAM 8-1-
DSLAM 8-2 :
DSLAM 1-1-
DSLAM 8-1 :
DSLAM 1-1-
DSLAM 8-2 :
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4444
ADSL Assessment ADSL Assessment ResultsResults
Delay and Lost Data Delay and Lost Data for G723for G723
Delay Evaluation by Hour
0%
20%
40%
60%
80%
100%
143
145
147
149
151
153
Del
ay (
ms)
Good 87%89%78%69%71%78%82%83%86%89%86%87%84%86%74%71%78%84%85%71%71%71%67%71%
Acceptable 13%11%23%31%29%22%18%18%14%11% 14%13%16%14%21%29%23%16%15%29%29%29%33%29%
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 5% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Delay (ms) 145 145 146 146 147 146 146 146 145 145 146 146 146 146 146 147 145 145 145 145 146 147 148 146
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Lost Data Evaluation by Hour
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0.00%
0.01%
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0.03%
0.04%
0.05%
Lo
st D
ata
(%)
Good 100 100 100 100 100 100 100 100 100 100 100 100 100 10095%100 100 100 100 100 100 100 100 100
Acceptable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
P oor 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Unavailable 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 5% 0% 0% 0% 0% 0% 0% 0% 0% 0%
Lost Data .01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.01%.03 .01%.01%.01%.01%
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EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4545
Conclusions: LANConclusions: LAN
The performance of IPT over LAN was perfect, even when an unrealistically exaggerated traffic was assumed (50% of users are busy on call).
The delay was at its minimum value (~ 40ms for G711 and ~130 ms for G723), and lost data and jitter loss was close to zero.
The MOS parameter was always approaching the maximum possible for each of the two codecs i.e. 4.38 for G711 and 3.65 for G723.
No noticeable variation on the call quality was observed during the span of 7 days nor during the span of the whole day.
No difference in performance may be attributed to the specific locations of the nodes or Busy Hour of data traffic.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4646
Conclusions on ADSLConclusions on ADSL Although the ADSL link is nowhere close to the
capacity of LAN, it is a dedicated link per house. For G711 codec call quality remained at maximum
possible throughout the duration of test. The delay was found to be well within the limits,
and jitter and lost data were almost negligible. All links behaved equally well without any effects
of local loop and of intra-DSALM or inter-DSLAM calls.
The results for the G 723 codec were similarly perfect, taking into considerations the slightly lower MOS value and slightly high delay due to the use of this compressed codec.
The DSLAM network can safely support maximum number of realistically expected calls from any typical house.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4747
ConclusionConclusion
Lowe traffic: The performance seems to be pretty good for more than
99% of the calls. The average delay was always below 45 ms Lost data was negligible (less than 0.03%). Moreover, all links performed equally well.
Medium Traffic: 33% of the calls became poor. High variation in call quality between different pairs of
nodes, some being consistently “good” and others being consistently “poor”.
By examining the poor links, we found one node common to all.
The channel between that node and the nearest Access Point is poor, therefore affecting all the communications where this node is involved.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4848
ConclusionConclusion
High Traffic call quality became poor most of the time (75%). we started to notice the effect of Busy Hours of
data traffic on IPT quality. The MOS of calls between 9 pm-8 am were
found to be 30% above that for calls between 8 am – 9 pm.
G723 results was similar in pattern to those of G711 with two differences: The best quality for this codec is “acceptable”
rather than “good”. It does not get much affected with data traffic
intensity.
EE Seminar, March 2009EE Seminar, March 2009 Evaluation of VoIP over University NetworksEvaluation of VoIP over University Networks 4949
Thank You