Performance Evaluation of SCTP in wireless networks

Tutors: Tania Jimenez and Yezekael Hayel

VICUNA, Nelson

Planning

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Introduction

Wireless Networks

SCTP

NS2

Performance Evaluation

Conclusion

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 anywhereto anyone

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Deployment

Flexibility

They can go where cable can not

Wireless Networks, ii

Properties

High bit-error rate (BER): random loss

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Bursty traffic: mixed voice/data, channel access problems

Disconnections: handoffs, interferences

Impact on TCP: Fast retransmit, timeouts, large and varying delay.

Wireless Networks, iii

Commonly used wireless networks

IEEE 802.11Standard for wireless LANs, ratified by the Institute of Electrical and Electronics Engineers (IEEE) in the year 1997.

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

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.

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.

SCTP, i

Stream Control Transmission Protocol

Transport protocol, designed by the Signaling Transport (SIGTRAN) group of the Internet Engineering Task Force (IETF)

Message-oriented protocol with all the necessary TCP-like mechanisms

SCTP provides sequencing, flow control, reliability and full-duplex data transfer like TCP

SCTP has unique features including multihoming and multistreaming

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Originally designed to support PSTN signaling messages over IP Networks

SCTP, iii

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

IP reference model

SCTP, TCP and UDP

Packet Format

Association

SCTP, iii

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

IP reference model

SCTP, TCP and UDP

Packet Format

Association

Protocol Feature SCTP TCPUDP

State required at each endpoint yes yes no

Reliable data transfer yes yes no

Congestion control and avoidance yes yes no

Message boundary conservation yes no yes

Path MTU discovery and message fragmentation yes yes no

Message bundling yes yes no

Multihomed hosts support yes no no

Multistream support yes no no

Unordered data delivery yes no yes

Security cookie against SYN flood attack yes no no

Built-in heartbeat (reachability check) yes no no

SCTP, iii

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

IP reference model

SCTP, TCP and UDP

Packet Format

Association

SCTP, iii

IP reference model

SCTP, TCP and UDP

Packet Format

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Association

SCTP, iv

Congestion Control

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Slow-start

Congestion Avoidance

Fast Retransmit

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.

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

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

NS-2, i

Network SimulatorDiscrete-time simulator whose development began in 1989with the development of REAL Network Simulator

SCTPThe SCTP module for NS-2 has been contributed by agroup at the University of Delaware

Supports some features of RFC 2960 (with draft-ietf-tsvwg-sctpimpguide-04.txt)

Distribution has General Public License (GPL) condition

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

NS-2, ii

SCTP structure in NS-2

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Performance Evaluation and Analysis, i

Schemas

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Wired Network

802.11

UMTS

WiMAX

Performance Evaluation and Analysis, ii

Topologies

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Wired Network

100Mbps

100Mbps

100Mbps

100Mbps

1Mbps

100Mbps

100Mbps

N1(1)

n1N1(2)

N1(m)

n0

N0(1)

N0(2)

N0(n)

bottleneck

Performance Evaluation and Analysis, ii

Topologies

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

802.11, UMTS and WiMAX

100Mbps

100Mbps

100Mbps

1Mbps

N1(1)

n1N1(2)

N1(m)

bottleneck

BS

N0(1)

N0(2)

N0(n)

Performance Evaluation and Analysis, iii

Measure variables

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Throughput

Delay

Packet loss

Average of data per second per client delivered over the bottleneck

Average of time that a packet of data takes from the origin to the destination

Packet loss due to network congestion.

Performance Evaluation and Analysis, iv

Experimental scenario

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

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) withdifferent rates of packet loss in wireless networks

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 1

Number of Clients: 1, 5, 10, 25, 50 and 100

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 1

Number of Clients: 1, 5, 10, 25, 50 and 100

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 1

Number of Clients: 1, 5, 10, 25, 50 and 100

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 2

Link Error, in %: 0, 5, 10, 25 and 50

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 2

Link Error, in %: 0, 5, 10, 25 and 50

Performance Evaluation and Analysis, iv

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

Loss Rate

Throughput

Delay

Experimental Scenario 2

Link Error, in %: 0, 5, 10, 25 and 50

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

VICUNA, Nelson

Performance Evaluation of SCTP in wireless networks

Questions

Nelson Vicuña Z.January - 2008

SCTP

Handshake

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

SCTP

Chunk Types

ID Value Chunk Type0 Payload Data (DATA)1 Initiation (INIT)2 Initiation Acknowledgement (INIT ACK)3 Selective Acknowledgement (SACK)4 Heartbeat Request (HEARTBEAT)5 Heartbeat Acknowledgement (HEARTBEAT ACK)6 Abort (ABORT)7 Shutdown (SHUTDOWN)8 Shutdown Acknowledgement (SHUTDOWN ACK)9 Operation Error (ERROR)10 State Cookie (COOKIE ECHO)11 Cookie Acknowledgement (COOKIE ACK)12 Reserved for Explicit Congestion Notification Echo (ECNE)13 Reserved for Congestion Window Reduced (CWR)14 Shutdown Complete (SHUTDOWN COMPLETE)15 to 62 reserved by IETF63 IETF-defined Chunk Extensions64 to 126 reserved by IETF127 IETF-defined Chunk Extensions128 to 190 reserved by IETF191 IETF-defined Chunk Extensions192 to 254 reserved by IETF255 IETF-defined Chunk Extensions

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

NS-2

SCTPSupports 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

VICUNA, Nelson

SCTP, i

Acknowledging DATA Chunks

TSN : Transmission Sequence Number

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

SCTPEndpoint A

SCTPEndpoint B

DATA chunk TSN=100

DATA chunk TSN=101

DATA chunk TSN=102

DATA chunk TSN=103

DATA chunk TSN=104

DATA chunk TSN=105

SACK chunk Cumulative TSN=108

DATA chunk TSN=106

DATA chunk TSN=107

DATA chunk TSN=108

SCTP, and ii

Performance Evaluation of SCTP in wireless networks

VICUNA, Nelson

DATA chunk TSN=112

DATA chunk TSN=113

DATA chunk TSN=117

DATA chunk TSN=119

DATA chunk TSN=120

DATA chunk TSN=116

SACK chunk Cumulative TSN=113Gap Ack Block #1 Start = +1 End = +3Gap Ack Block #2 Start = +10 End = +11

DATA chunk TSN=111

DATA chunk TSN=110

DATA chunk TSN=121

DATA chunk TSN=122

XDATA chunk TSN=123

DATA chunk TSN=124

DATA chunk TSN=125

DATA chunk TSN=126

DATA chunk TSN=114X

DATA chunk TSN=115X

DATA chunk TSN=118

Acknowledging DATA Chunks

TSN : Transmission Sequence Number