Transcript Slides

Performance Evaluation of SCTP in
wireless networks
Tutors: Tania Jimenez and Yezekael Hayel
VICUNA, Nelson
Planning
Introduction
Wireless Networks
SCTP
NS2
Performance Evaluation
Conclusion
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Introduction
Most of the variants TCP offer good benefits in wired
networks, based on the assumption that most of the losses
were due to the congestion.
But in a wireless network, packet losses are mainly due to
high rates of losses caused by bit poor conditions spread.
Additionally, wireless networks have certain characteristics
such as high latency, high packet loss and bandwidth variable
posed conflicts of the abilities of TCP.
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Wireless Networks, i
Several advantages
Mobility
Allows transmit real-time information anywhere
to anyone
Deployment
Flexibility
They can go where cable can not
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Wireless Networks, ii
Properties
High bit-error rate (BER): random loss
Bursty traffic: mixed voice/data, channel access problems
Disconnections: handoffs, interferences
Impact on TCP:
Fast retransmit, timeouts, large and varying delay.
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Wireless Networks, iii
Commonly used wireless networks
IEEE 802.11
Standard for wireless LANs, ratified by the Institute of Electrical and
Electronics Engineers (IEEE) in the year 1997.
UMTS (Universal Mobile Telecommunications System)
The intention is to create and extend the capability of today’s mobile, cordless
and other satellite technologies using the Global System for Mobile
communication (GSM) core infrastructure.
WiMAX (Worldwide Interoperability for Microwave Access)
Standards-based technology enabling the delivery of last mile
wireless broadband access as an alternative to cable and DSL.
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, i
Stream Control Transmission Protocol
Transport protocol, designed by the Signaling Transport
(SIGTRAN) group of the Internet Engineering Task Force (IETF)
Originally designed to support PSTN signaling messages
over IP Networks
Message-oriented protocol with all the necessary TCP-like
mechanisms
SCTP provides sequencing, flow control, reliability and fullduplex data transfer like TCP
SCTP has unique features including multihoming and
multistreaming
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, iii
IP reference model
SCTP, TCP and UDP
Packet Format
Association
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, iii
IP reference model
SCTP, TCP and UDP
Packet Format
Association
Protocol Feature
SCTP
TCP
UDP
State required at each endpoint
Reliable data transfer
Congestion control and avoidance
Message boundary conservation
Path MTU discovery and message fragmentation
Message bundling
Multihomed hosts support
Multistream support
Unordered data delivery
Security cookie against SYN flood attack
Built-in heartbeat (reachability check)
yes
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Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, iii
IP reference model
SCTP, TCP and UDP
Packet Format
Association
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, iii
IP reference model
SCTP, TCP and UDP
Packet Format
Association
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, iv
Congestion Control
Slow-start
Congestion Avoidance
Fast Retransmit
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP, v
Differences from TCP Congestion Control
cwnd, the initial congestion window, is suggested to be 2*MTU in
SCTP, which is usually one MTU in TCP
In SCTP, the increase of the cwnd is controlled by the number of
acknowledged bytes; while in TCP, it is controlled by the
number of new acknowledgement received.
In SCTP, fast retransmission is triggered by the fourth missing
report of a chunk; while in TCP, three duplicate ACK triggers
fast retransmission
SCTP has no explicit fast recovery algorithm that is used in TCP
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
NS-2, i
Network Simulator
Discrete-time simulator whose development began in 1989
with the development of REAL Network Simulator
Distribution has General Public License (GPL) condition
SCTP
The SCTP module for NS-2 has been contributed by a
group at the University of Delaware
Supports some features of RFC 2960
(with draft-ietf-tsvwg-sctpimpguide-04.txt)
Performance Evaluation of SCTP in wireless networks
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NS-2, ii
SCTP structure in NS-2
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, i
Schemas
Wired Network
802.11
UMTS
WiMAX
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, ii
Topologies
Wired Network
N1(1)
N0(1)
100Mbps
100Mbps
bottleneck
100Mbps
100Mbps
1Mbps
N0(2)
n0
100Mbps
N0(n)
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
N1(2)
n1
100Mbps
N1(m)
Performance Evaluation and Analysis, ii
Topologies
802.11, UMTS and WiMAX
N1(1)
N0(1)
100Mbps
bottleneck
N0(2)
100Mbps
1Mbps
BS
N1(2)
n1
100Mbps
N0(n)
N1(m)
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, iii
Measure variables
Throughput
Average of data per second per client delivered over the bottleneck
Delay
Average of time that a packet of data takes from the origin to the
destination
Packet loss
Packet loss due to network congestion.
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, iv
Experimental scenario
FTP transmission with different numbers of clients in wireless
networks stable state (no packet loss for link conditions)
FTP transmission with a fixed number of clients (50) with
different rates of packet loss in wireless networks
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, iv
Experimental
Scenario 1
Number of Clients:
1, 5, 10, 25, 50 and 100
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, iv
Experimental
Scenario 1
Number of Clients:
1, 5, 10, 25, 50 and 100
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Performance Evaluation and Analysis, iv
Experimental
Scenario 1
Number of Clients:
1, 5, 10, 25, 50 and 100
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
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Performance Evaluation and Analysis, iv
Experimental
Scenario 2
Link Error, in %:
0, 5, 10, 25 and 50
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Performance Evaluation and Analysis, iv
Experimental
Scenario 2
Link Error, in %:
0, 5, 10, 25 and 50
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Performance Evaluation and Analysis, iv
Experimental
Scenario 2
Link Error, in %:
0, 5, 10, 25 and 50
Loss Rate
Throughput
Delay
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
Conclusion
SCTP and TCP behaves in very similar ways in wireless
networks. It is natural the similarity of their behaviors
because both are based on the same algorithms of
control congestion. However, SCTP has better
performance than TCP, especially in the presence of
congestion.
Performance Evaluation of SCTP in wireless networks
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Questions
Performance Evaluation of SCTP in
wireless networks
Nelson Vicuña Z.
January - 2008
SCTP
Handshake
Performance Evaluation of SCTP in wireless networks
VICUNA, Nelson
SCTP
Chunk Types
ID
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 to 62
63
64 to 126
127
128 to 190
191
192 to 254
255
Value Chunk Type
Payload Data (DATA)
Initiation (INIT)
Initiation Acknowledgement (INIT ACK)
Selective Acknowledgement (SACK)
Heartbeat Request (HEARTBEAT)
Heartbeat Acknowledgement (HEARTBEAT ACK)
Abort (ABORT)
Shutdown (SHUTDOWN)
Shutdown Acknowledgement (SHUTDOWN ACK)
Operation Error (ERROR)
State Cookie (COOKIE ECHO)
Cookie Acknowledgement (COOKIE ACK)
Reserved for Explicit Congestion Notification Echo (ECNE)
Reserved for Congestion Window Reduced (CWR)
Shutdown Complete (SHUTDOWN COMPLETE)
reserved by IETF
IETF-defined Chunk Extensions
reserved by IETF
IETF-defined Chunk Extensions
reserved by IETF
IETF-defined Chunk Extensions
reserved by IETF
IETF-defined Chunk Extensions
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NS-2
SCTP
Supports the features in the following sections of RFC 2960:
• Section 5.1 Normal Establishment of an Association (rudimentary
handshake)
• Section 6.1 Transmission of DATA Chunks
• Section 6.2 Acknowledgement of Reception of DATA Chunks
• Section 6.3 Management Retransmission Timer
• Section 6.4 Multi-homed SCTP Endpoints
• Section 6.5 Stream Identifier and Stream Sequence Number
• Section 6.6 Ordered and Unordered Delivery
• Section 6.7 Report Gaps in Received DATA TSNs
• Section 7.2 SCTP Slow-Start and Congestion Avoidance
• Section 8.1 Endpoint Failure Detection
• Section 8.2 Path Failure Detection
• Section 8.3 Path Heartbeat (without upper layer control)
Performance Evaluation of SCTP in wireless networks
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SCTP, i
Acknowledging DATA
Chunks
SCTP
Endpoint A
SCTP
Endpoint B
DATA chunk TSN=100
TSN : Transmission
Sequence Number
DATA chunk TSN=101
DATA chunk TSN=102
DATA chunk TSN=103
DATA chunk TSN=104
DATA chunk TSN=105
DATA chunk TSN=106
DATA chunk TSN=107
DATA chunk TSN=108
SACK chunk Cumulative TSN=108
Performance Evaluation of SCTP in wireless networks
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SCTP, and ii
DATA chunk TSN=110
DATA chunk TSN=111
Acknowledging DATA
Chunks
DATA chunk TSN=112
DATA chunk TSN=113
DATA chunk TSN=114
TSN : Transmission
Sequence Number
DATA chunk TSN=115
DATA chunk TSN=116
X
X
DATA chunk TSN=117
DATA chunk TSN=118
DATA chunk TSN=119
DATA chunk TSN=120
DATA chunk TSN=121
DATA chunk TSN=122
DATA chunk TSN=123
DATA chunk TSN=124
DATA chunk TSN=125
DATA chunk TSN=126
SACK chunk Cumulative TSN=113
Gap Ack Block #1 Start = +1 End = +3
Gap Ack Block #2 Start = +10 End = +11
Performance Evaluation of SCTP in wireless networks
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X