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Performance Analysis for VoIP System B92902088 邱柏儒 B92902093 紀忠毅 B92902106 莊典融...
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Transcript of Performance Analysis for VoIP System B92902088 邱柏儒 B92902093 紀忠毅 B92902106 莊典融...
PerformanceAnalysis for VoIP SystemPerformanceAnalysis for VoIP System
B92902088 邱柏儒B92902093 紀忠毅B92902106 莊典融B92902120 孟昭宏
B92902088 邱柏儒B92902093 紀忠毅B92902106 莊典融B92902120 孟昭宏
AgendaAgenda
Modeling VoIP (莊典融 )
VoIP in Ethernet (紀忠毅 )
An Example in Performance AnalysisVoIP in Wireless LAN (孟昭宏 )
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary (邱柏儒 )
Modeling VoIP (莊典融 )
VoIP in Ethernet (紀忠毅 )
An Example in Performance AnalysisVoIP in Wireless LAN (孟昭宏 )
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary (邱柏儒 )
AgendaAgenda
Modeling VoIPVoIP in Ethernet
An Example in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
Modeling VoIPVoIP in Ethernet
An Example in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
Modeling VoIPModeling VoIP
How to model VoIP trafficModeling by distributionModeling by state diagram
Pros and Cons
How to model VoIP trafficModeling by distributionModeling by state diagram
Pros and Cons
Modeling by Distribution(1)Modeling by
Distribution(1)Modeling data traffic
The data size distribution of Internet traffic which uses the TCP (many smaller files, few larger ones) seen as approximately Pareto-distributed.
Modeling data trafficThe data size distribution of Internet
traffic which uses the TCP (many smaller files, few larger ones) seen as approximately Pareto-distributed.
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2
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Modeling by Distribution(2)Modeling by
Distribution(2)
Model Phase Mean Comment
Web traffic generator
1.21.52
12(kB)0.5(sec)50,10(sec)
“ object size”“inter-object”“inter-page”
HTTP reply traces 1.04-1.14
FTP traffic 1.18 80(kB) Exponential session and burse inter-arrival time
Published Pareto distribution parameters used in modeling internet data traffic. Choose appreciate environment
Modeling data trafficModeling data traffic
Modeling by Distribution(3)Modeling by
Distribution(3)Run SimulatorAnalysis and diagnosis
DelayPacket lossJitters
Run SimulatorAnalysis and diagnosis
DelayPacket lossJitters
Modeling by State Diagram(1)
Modeling by State Diagram(1)
Modeling speech processModeling speech process
Modeling by State Diagram(2)
Modeling by State Diagram(2)
Modeling speech processModeling speech process
Pros and ConsPros and Cons
Inaccurate on modelingVariant and complex
Simulator is different from real worldUnexpected problems on hardware
Low costWe can implement solution after
getting good simulation.
Inaccurate on modelingVariant and complex
Simulator is different from real worldUnexpected problems on hardware
Low costWe can implement solution after
getting good simulation.
AgendaAgenda
Modeling VoIPVoIP in Ethernet
An Example in Performance AnalysisVoIP in Wireless Lan
Solutions to Performance Problems in VoIP over a 802.11 Wireless Lan
Summary
Modeling VoIPVoIP in Ethernet
An Example in Performance AnalysisVoIP in Wireless Lan
Solutions to Performance Problems in VoIP over a 802.11 Wireless Lan
Summary
Critical VoIP Performance Challenges
Critical VoIP Performance Challenges
Latency Jitter Packet
Loss Echo
Latency Jitter Packet
Loss Echo Receiver
(Packet Lost)
1 2 3 4 5
Packet Interval
Sender
Receiver (Jitter)
1 3 5
1 2 3 4 5
Receiver (Delay)
1 2 3 4
LatencyLatency
1. Good: < 80msAcceptable: 150~180ms (each way)
2. Must be addressed with VoIP protocols. Eg, SIP, H.323
3. Commonly associated with network congestion and poor bandwidth management. Not in LAN but at LAN/WAN boundary.
1. Good: < 80msAcceptable: 150~180ms (each way)
2. Must be addressed with VoIP protocols. Eg, SIP, H.323
3. Commonly associated with network congestion and poor bandwidth management. Not in LAN but at LAN/WAN boundary.
LatencyLatency
4. Minimize delay/latency Queuing techniques
Eq, DiffServ, 802.1p/q Voice packet priority over other traffic
More stringent, intelligent bandwidth management/QoS Guaranteed amount of bandwidth to
each traffic type.
4. Minimize delay/latency Queuing techniques
Eq, DiffServ, 802.1p/q Voice packet priority over other traffic
More stringent, intelligent bandwidth management/QoS Guaranteed amount of bandwidth to
each traffic type.
JitterJitter
1. Tolerance range: 20~30ms2. Possible solutions
Jitter buffer Temporarily store Smooth out the delivery of voice packet
Router queue
1. Tolerance range: 20~30ms2. Possible solutions
Jitter buffer Temporarily store Smooth out the delivery of voice packet
Router queue
JitterJitter
3. Prevent jitter TCP rate control (for data traffic) UDP rate control (for voice traffic)
Eq, Packeteer’s Application Traffic Management System
Policy-based bandwidth management or QoS strategy
3. Prevent jitter TCP rate control (for data traffic) UDP rate control (for voice traffic)
Eq, Packeteer’s Application Traffic Management System
Policy-based bandwidth management or QoS strategy
Packet LossPacket Loss
1. Loss rate < 1%: OK2. Loss rate > 3%: conversation
seems “breaking up”3. IP: best effort4. Serious packet loss may cause
dropped calls or even system failure
1. Loss rate < 1%: OK2. Loss rate > 3%: conversation
seems “breaking up”3. IP: best effort4. Serious packet loss may cause
dropped calls or even system failure
Packet LossPacket Loss
5. Prevent packet loss Apply more control IP: best effort predictable
5. Prevent packet loss Apply more control IP: best effort predictable
Solution to Improve Quality
Solution to Improve Quality
• PLC (Packet Lost Concealment) Packet Lost
• Dynamic Jitter Buffer Jitter
• Bandwidth Reservation / Packet Priorities / Queuing Delay
• G.168 Echo cancellation Echo
• VAD (Voice Active Detection) Save Bandwidth
• PLC (Packet Lost Concealment) Packet Lost
• Dynamic Jitter Buffer Jitter
• Bandwidth Reservation / Packet Priorities / Queuing Delay
• G.168 Echo cancellation Echo
• VAD (Voice Active Detection) Save Bandwidth
An Example in Performance Analysis
An Example in Performance Analysis
Testing coverageTesting environmentTesting Equipment & SoftwareREDCOM performer
QProMediaPro
Testing coverageTesting environmentTesting Equipment & SoftwareREDCOM performer
QProMediaPro
Testing CoverageTesting Coverage
1. Functionality e.g VoIP/PSTN call, QoS, SIP/Phone Setting
2. Performance e.g QoS/RTP measurement
3. Stress e.g VoIP call with data integration
1. Functionality e.g VoIP/PSTN call, QoS, SIP/Phone Setting
2. Performance e.g QoS/RTP measurement
3. Stress e.g VoIP call with data integration
Testing CoverageTesting Coverage
4. Reliability e.g Long term VoIP / Continuous VoIP call
5. Interoperability e.g Cisco ATA/IP Phone/SoftPhone
4. Reliability e.g Long term VoIP / Continuous VoIP call
5. Interoperability e.g Cisco ATA/IP Phone/SoftPhone
Testing Environment (1/2)Testing Environment (1/2)
Testing Environment (2/2)Testing Environment (2/2)
Pure EnvironmentDirect connection
Congestion EnvironmentSmart-bit tools
Pure EnvironmentDirect connection
Congestion EnvironmentSmart-bit tools
Testing Equipment & Software
Testing Equipment & Software
EXCEL 9000
• PSTN simulator
RADCOM Performer
• QPro –Voice quality measurement
• MediaPro – VoIP protocol analysis
ProLAB
• SIP Proxy server / H.323 Gateway
• SIP UA simulator / H.323 Client
VoIP Phone
• Cisco 7940 IP Phone
• XTEN / Windows Messenger
Analysis Tool
Ethereal / CoolEdit
REDCOM PerformerREDCOM Performer
QProProvide voice quality measurement
MediaProProvide VoIP protocol flow analysis
QProProvide voice quality measurement
MediaProProvide VoIP protocol flow analysis
QPro – Line ConfigurationQPro – Line Configuration
QPro – Phone ConfigurationQPro – Phone Configuration
QPro – Call SettingQPro – Call Setting
QPro – Test Result (1/2)QPro – Test Result (1/2)
QPro – Test Result (2/2)QPro – Test Result (2/2)
QPro - SummaryQPro - Summary
AgendaAgenda
Modeling VoIPVoIP in Ethernet
A Case Study in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
Modeling VoIPVoIP in Ethernet
A Case Study in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
VoIP in Wireless LAN - outline
VoIP in Wireless LAN - outline
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
The Problems faced by WLAN
The Problems faced by WLAN
System CapacitySystem capacity for voice can be quite low
Other data trafficData from traditional App can interfere with each other
System CapacitySystem capacity for voice can be quite low
Other data trafficData from traditional App can interfere with each other
VoIP in 802.11bVoIP in 802.11b
VoIP in WLAN can potentially support more than 500 sessions in theory
In practice, only 12 are supported due to various overhead
VoIP in WLAN can potentially support more than 500 sessions in theory
In practice, only 12 are supported due to various overhead
VoIP in 802.11bVoIP in 802.11b
Support data rate up to 11Mb/sA VoIP stream typically requires
less than 10kb/sThe number of simultaneous VoIP
streams that can be supported by an 802.11b in theory is around 11M/10K = 1100
About 550 VoIP sessions
Support data rate up to 11Mb/sA VoIP stream typically requires
less than 10kb/sThe number of simultaneous VoIP
streams that can be supported by an 802.11b in theory is around 11M/10K = 1100
About 550 VoIP sessions
VoIP in 802.11bVoIP in 802.11b
In practice, no more than a few VoIP sessions
If GSM 6.10 codec is used, the maximum is 12
The result is mainly due to added packet header overheads as well as the inefficiency inherent in the WLAN MAC
In practice, no more than a few VoIP sessions
If GSM 6.10 codec is used, the maximum is 12
The result is mainly due to added packet header overheads as well as the inefficiency inherent in the WLAN MAC
VoIP in 802.11bVoIP in 802.11b
IP + UDP + RTP header = 40bytesVoIP payload ranging from 10 to
30 bytesThe transmission time:
30 * 8 / 11 = 22 us40 * 8 / 11 = 29 us
Efficiency drops to less than 50%
IP + UDP + RTP header = 40bytesVoIP payload ranging from 10 to
30 bytesThe transmission time:
30 * 8 / 11 = 22 us40 * 8 / 11 = 29 us
Efficiency drops to less than 50%
VoIP in 802.11bVoIP in 802.11b
Physical layer have additional overhead more than 800 us
Attributed to the Physical preamble, MAC header, MAC backoff time, MAC ACK, Inter-transmission time
Overall efficiency drops to less than 3%
Physical layer have additional overhead more than 800 us
Attributed to the Physical preamble, MAC header, MAC backoff time, MAC ACK, Inter-transmission time
Overall efficiency drops to less than 3%
VoIP in 802.11bVoIP in 802.11b
TCP connection will cause unacceptably large increase in the delay and packet loss rate of VoIP traffic
TCP connection will cause unacceptably large increase in the delay and packet loss rate of VoIP traffic
VoIP in Wireless LAN - outline
VoIP in Wireless LAN - outline
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
An 802.11 WLAN is referred to as the basic service set (BSS) in the standard specification
There are two types of BSSs: Independent BSS and
Infrastructure BSS.
An 802.11 WLAN is referred to as the basic service set (BSS) in the standard specification
There are two types of BSSs: Independent BSS and
Infrastructure BSS.
Ad Hoc (Independent) BSSAd Hoc (Independent) BSS
Infrastructure BSSInfrastructure BSS
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Focus on infrastructure BSSAssume that all voice streams are
between stations in different BSSEach AP has two interfaces, an
802.11 interface, and an Ethernet interface which is connected to the voice gateway.
Focus on infrastructure BSSAssume that all voice streams are
between stations in different BSSEach AP has two interfaces, an
802.11 interface, and an Ethernet interface which is connected to the voice gateway.
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Within a BSS, there are two streams for each VoIP session.
M-M Scheme idea : Combine the data from several
downlink streams into a single packet for multicast over the WLAN to their destinations
Within a BSS, there are two streams for each VoIP session.
M-M Scheme idea : Combine the data from several
downlink streams into a single packet for multicast over the WLAN to their destinations
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
The voice multiplexer resides in the voice gateway for H.323
The MUX can also resides in a specially designed AP or a server between the voice gateway and AP
The voice multiplexer resides in the voice gateway for H.323
The MUX can also resides in a specially designed AP or a server between the voice gateway and AP
Multiplex-Multicast Procedure
Multiplex-Multicast Procedure
The download link VoIP traffic first goes through a MUX in the voice gateway
The MUX replaces the RTP, UDP, IP header of each packet with a compressed mini header
In mini header, there is an ID used to identify the session of the VoIP packet
The download link VoIP traffic first goes through a MUX in the voice gateway
The MUX replaces the RTP, UDP, IP header of each packet with a compressed mini header
In mini header, there is an ID used to identify the session of the VoIP packet
Multiplex-Multicast Procedure
Multiplex-Multicast Procedure
Then multicast the multiplexed packet to the WLAN through AP
The DEMUX at the receiver restores the original RTP header and necessary information
Then multicast the multiplexed packet to the WLAN through AP
The DEMUX at the receiver restores the original RTP header and necessary information
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Header
Data1
Header
Header
Data2
Data3
HeaderMinih + Data1 + Minih + Data2
…
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
AdvantagesAdvantages
Reduce the number of VoIP streams in one BSS from 2n to 1 + n, where n is the number of VoIP sessions.
Improve the bandwidth efficiency
Reduce the number of VoIP streams in one BSS from 2n to 1 + n, where n is the number of VoIP sessions.
Improve the bandwidth efficiency
TradeoffTradeoff
The MUX sends out a multiplexed packet every T ms, which is equal to or shorter than the VoIP inter-packet interval.
For GSM 6.10, the inter-packet interval is 20 ms.
Larger value of T can improve bandwidth efficiency
The MUX sends out a multiplexed packet every T ms, which is equal to or shorter than the VoIP inter-packet interval.
For GSM 6.10, the inter-packet interval is 20 ms.
Larger value of T can improve bandwidth efficiency
Tradeoff (cont.)Tradeoff (cont.)
But the larger T will cause more delay
One can control the tradeoff between bandwidth efficiency and delay by adjusting T
But the larger T will cause more delay
One can control the tradeoff between bandwidth efficiency and delay by adjusting T
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Multiplex-Multicast Scheme
Should be solved by encrypting the voice packet
Should be solved by encrypting the voice packet
VoIP in Wireless LAN - outline
VoIP in Wireless LAN - outline
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
CSMA/CA AlgorithmCSMA/CA Algorithm
Capacity AnalysisCapacity Analysis
n : maximum number of sessions that can be supported
Tdown & Tup: transmission times for downlink and uplink packets
Tavg: average time between the transmissions of two consecutive packets in a WLAN
NP : number of packets sent by one stream in one second
1/Tavg = number of streams * NP
n : maximum number of sessions that can be supported
Tdown & Tup: transmission times for downlink and uplink packets
Tavg: average time between the transmissions of two consecutive packets in a WLAN
NP : number of packets sent by one stream in one second
1/Tavg = number of streams * NP
Capacity of Ordinary VoIPCapacity of Ordinary VoIP
OHhdr = HRTP + HUDP + HIP + HMAC
OHsender = DIFS + averageCW + PHY if unicast packet:
OHreceiver = SIFS + ACK
Tdown = Tup = (Payload +OHhdr) * 8 / dataRate + OHsender + OHreceiver
OHhdr = HRTP + HUDP + HIP + HMAC
OHsender = DIFS + averageCW + PHY if unicast packet:
OHreceiver = SIFS + ACK
Tdown = Tup = (Payload +OHhdr) * 8 / dataRate + OHsender + OHreceiver
Capacity of Ordinary VoIPCapacity of Ordinary VoIP
n downlink and n uplink unicast streams
Tavg = (Tdown + Tup) / 2
1/Tavg = 2n *Np
n = 11
n downlink and n uplink unicast streams
Tavg = (Tdown + Tup) / 2
1/Tavg = 2n *Np
n = 11
Capacity of M-M SchemeCapacity of M-M Scheme
the RTP, UDP and IP header of each packet is compressed to 2 bytes
Tdown = [(Payload + 2) *n + HUDP + HIP + HMAC] * 8 / dataRate + OHsender
Tavg = (Tdown + n *Tup) / (n + 1)
1/Tavg = (n + 1) *Np n = 21.2
the RTP, UDP and IP header of each packet is compressed to 2 bytes
Tdown = [(Payload + 2) *n + HUDP + HIP + HMAC] * 8 / dataRate + OHsender
Tavg = (Tdown + n *Tup) / (n + 1)
1/Tavg = (n + 1) *Np n = 21.2
Capacities assuming Different Codecs
Capacities assuming Different Codecs
Codecs Ordinary VoIPMultiplex-Multicast
Scheme
GSM 6.10 11.2 21.2
G.711 10.2 17.7
G.723.1 17.2 33.2
G.726-32 10.8 19.8
G.729 11.4 21.7
SimulationsSimulations
increase the number of VoIP sessions until the per stream packet loss rate exceeds 1%
system capacity = max number of sessions
assume that the retry limit for each packet is 3
increase the number of VoIP sessions until the per stream packet loss rate exceeds 1%
system capacity = max number of sessions
assume that the retry limit for each packet is 3
SimulationsSimulations
For ordinary VoIP over WLAN, the system capacity is 12
Exceeding the system capacity leads to a large surge in packet losses for the downlink streams
For ordinary VoIP over WLAN, the system capacity is 12
Exceeding the system capacity leads to a large surge in packet losses for the downlink streams
Analysis V.S. SimulationAnalysis V.S. Simulation
Different Schemes Analysis Simulation
Original VoIP 11.2 12
Multiplex-MulticastScheme
21.2 22
VoIP in Wireless LAN - outline
VoIP in Wireless LAN - outline
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
IntroductionVoIP Multiplex Multicast
SchemeCapacity AnalysisConclusion
ConclusionsConclusions
M-M scheme can reduce the large overhead when VoIP traffic is delivered over WLAN
it requires no changes to the MAC protocol at the wireless end stations
more readily deployable over the existing network infrastructure.
it makes the voice capacity nearly 100% higher than ordinary VoIP
M-M scheme can reduce the large overhead when VoIP traffic is delivered over WLAN
it requires no changes to the MAC protocol at the wireless end stations
more readily deployable over the existing network infrastructure.
it makes the voice capacity nearly 100% higher than ordinary VoIP
AgendaAgenda
Modeling VoIPVoIP in Ethernet
A Case Study in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
Modeling VoIPVoIP in Ethernet
A Case Study in Performance AnalysisVoIP in Wireless LAN
Solutions to Performance Problems in VoIP over a 802.11 Wireless LAN
Summary
Summary(1/2)Summary(1/2)
Mathematical modeling- Queuing theory Poisson distribution Pareto distribution- Inaccuracy
Industrial testing method Performance in various
environments- Ethernet- Wireless
Mathematical modeling- Queuing theory Poisson distribution Pareto distribution- Inaccuracy
Industrial testing method Performance in various
environments- Ethernet- Wireless
Summary(2/2)Summary(2/2)
Improvement- e.g. priority queue, jitter absorption, loss concealment. - QoS absolute QoS level relative QoS level e.g. Expedited Forwarding, Assured Forwarding.
Improvement- e.g. priority queue, jitter absorption, loss concealment. - QoS absolute QoS level relative QoS level e.g. Expedited Forwarding, Assured Forwarding.
ReferenceReference
P.M. Fiorini: Voice over IP for Enterprise Networks: Performance Implications & Traffic Models
E. Noel & K.W. Tang: Performance Analysis of a VoIP Access Architecture
Wei Wang: Solutions To Performance Problems In VoIP Over A 802.11 Wireless LAN
P.M. Fiorini: Voice over IP for Enterprise Networks: Performance Implications & Traffic Models
E. Noel & K.W. Tang: Performance Analysis of a VoIP Access Architecture
Wei Wang: Solutions To Performance Problems In VoIP Over A 802.11 Wireless LAN
Q & AQ & A
Thanks for your listening…
Thanks for your listening…