NS Simulator Studying For Stream Control Transmission Protocol

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NS Simulator Studying ForStream Control
Transmission Protocol

• CSCI8211 Project Presentation
• Ke Zhang
• Computer Science Engineering
• University of Minnesota

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Outline

• Myself
• Motivation for this project
• Background
• My work
• Results
• Conclusions Future Work
• References

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Who am I?

• Working as a full-time Programmer _at_ Silicon
  Graphics, Inc (SGI, famous for its graphics
  technology and IRIX OS)
• Currently, pursuing master degree of MICS program
  _at_ Computer Science Engineering Department of U
  of Minnesota
• First time coming to University campus
• Planning to graduate Fall, 2003

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Motivation for Steaming video/audio Technology

• I am directly benefit from this technology
  taking every class by streaming video offered by
  Unite program of U of M
• Original topic Security issue for streaming
  video/audio for RealNetwork technology
• Case study Only allow users view the stream
  video/audio. Dont allow save!
• Give it up due to technical difficulties

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Motivation for developing SCTP

• Transportation of telephony signaling messages
  over IP networks rigid timing and reliability
  requirements (Driven by moving from PSTNpublic
  switched telephone network or Plain Old Telephone
  Service to packet based Internet for
  telecommunication connection)
• Problems for TCP and UDP
• TCP
• Byte-Stream Oriented
• Provides strict ordering of information, which
  causes Head of Line Blocking(HOL) problem
• No built-in support for multi-homed IP hosts
• Vulnerable for SYN flooding attacks
• UDP
• Unreliable data transfer
• No congestion/flow control (application must
  handle it by itself)
• Solution need a new Transport Layer Protocol ?
  SCTP

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What is SCTP?

• An end-to-end, connection-oriented transport
  protocol that transports data in independent
  sequenced streams
• The Signaling Transport (SIGTRAN) group of the
  Internet Engineering Task Force (IETF) defines
  SCTP standards in RFC 2960 (October 2000)
• Transport layer protocol which operates on top of
  an unreliable connectionless network layer such
  as IP.
• SCTP could be implemented in network systems and
  applications that deliver voice/data and support
  quality real-time services (e.g., streaming video
  and multimedia).

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SCTP Features

• End-to-end reliable transportation service over
  IP networks
• Support multiple streams
• Multiple streams per assocation
• solves HOL blocking problem and enables partial
  ordering.
• Support for multi-homed hosts
• Multiple IP addresses per host
• More tolerant to network failures
• Message-oriented conserves message boundaries
• Unordered delivery SCTP can deliver message as
  ordered or unordered.
• Congestion Control SCTP congestion control is
  similar to TCP.
• Enables seamless introduction of SCTP into IP
  networks
• SCTP is rate adaptive similar to TCP.
• AIMD (Additive Increase/Multiplicative Decrease)
  algorithm with slow start, congestion avoidance,
  fast retransmit and fast recovery. SCTP uses
  delayed SACKs and duplicate SACKs.

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Feature Comparison
Feature SCTP TCP UDP
State required at endpoints X X
Reliable Data Transfer X X
Multi-homed Host Support X
Multi-Stream Support X
Security against SYN attacks X
Unordered Data Delivery X X
Failure detection (Heartbeat) X
Message bundling X
Congestion control and avoidance X X
Message boundary conservation X X
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SCTP Packets

• Each SCTP packet contains 1 or more Chunks
• Each Chunk has a common header type, flags,
  length
• Example Chunk types DATA, SACK, INIT

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SCTP Packets Another view
32 bits
Source Port
Dest. Port
SCTP
Verification Tag
Common
Header
Checksum
Type
Flags
Length
Chunk 1 Control/Data
Data Segment 1
MTU
Resv.U,B,E
Type
Length
n
TSN
Chunk Data Chunk
Stream Sequence n
Stream Identifier S
Payload Protocol Identifier
User Data (seq n of Stream S)
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SCTP Packet details

• The common headers includes
• The source port address
• The destination port address
• The verification tag
• The checksum of the entire packet
• The chunk fields includes
• The chunk-type field identifies the type of
  chunk being transmitted (Currently, 16 different
  types of chunks 1 DATA chunk 15 control
  chunks)
• The chunk flag specifies whether bits will be
  used in the association
• The chunk length determines the size of the
  entire chunk in bytes
• The chunk data includes the actual data payload
  of the chunk

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SCTP Basic terms

• SCTP Endpoint is the logical end of the SCTP
  transport protocol.
• Multi-homed SCTP Endpoint a list of SCTP
  transport addresses on the machine that share a
  single SCTP port.
• E.g. endpoint A 123.23.45.5, 137.38.84.4 100
• SCTP Association Similar to TCP connection.
• An association between two SCTP end points allows
  the transfer of both application data and control
  data
• Association begins with an initiation and is
  maintained until all data has been successfully
  transmitted and received. Once all data is
  successfully received, the association is
  gracefully terminated through a shutdown
• Denotes by a pair of two SCTP endpoints. E.g.
  association 123.23.45.5, 137.38.84.4 100
  35.43.121.34200

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Responsibility of STCP Endpoints
SCTP user application
Stream sequence delivery
Association startup and shutdown
Message fragmentation
Acknowledgement Congestion control
Message bundling
Packet validation
Path Management
IP Network
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SCTP Unordered Messages

• Any message may be marked as Unordered.
• Unordered message 3 will not wait for lost
  message 1 in this case
• Unordered Message avoid Head of Line Blocking
  problem.

4 csci8211
4 hello
3U world
Receiver
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Multiple stream feature of SCTP

• SCTP stream represents a sequence of messages
• SCTP accomplishes multistreaming by creating
  independence between
• Data transmission (uses Transport Sequence
  Number)
• Data delivery ( uses Stream Sequence Number)

• In the normal case, each message is delivered to
  the receiver in its order of transmission within
  the stream
• A message may also be specified by the sending
  application as unordered

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Multihoming

• SCTP can support multiple IP addresses in an
  association
• Requires multiple Network Interface Cards
• Peer need to select primary transport address

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Flow Control Congestion Control

• SCTP uses an end-to-end window based flow and
  congestion control (similar to TCP)
• AIMD algorithm with Slow Start and Congestion
  Avoidance, fast retransmit and fast recovery
• SCTP uses selective Acknowledgement (SACK)

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NS-2 Simulations

• Why choosing NS-2?
• NS-2 is a popular tool for network simulation
  study
• SCTP is available for NS-2
• Features of SCTP module for NS-2
• Establishment of association
• Multi-homed SCTP endpoints
• Ordered and Unordered Delivery
• SCTP Slow-start and Congestion Control
• Endpoint and Path Failure Detection

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Problems in NS2 Installation and Simulation

• Need install cygwin first (www.cygwin.com) on my
  laptop
• Only ns2 versions for window-based cygwin env are
  ns-2.1b.9a and ns-2.26
• Installation packet _at_ http//www.cs.virginia.edu
  /nc2y/ns-cygwin.shtml
• Installed latest ns-2.26 on my laptop
• SCTP patch for ns-2 is contributed by a group at
  the University of Delware.
• Installation packet _at_ http//pel.cis.udel.edu/
• Only works for ns-2.1b8 version
• My strategy
• Install ns-2.1b8 on my laptop first
• Apply SCTP patch to ns-2.1b8 to get the list of
  all files that are touched by SCTP packet
• Go through the whole patch file for SCTP and
  applies the changes to each files for ns-2.26
  installation on my laptop
• Compile ns-2.26

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Fairness between TCP and SCTP

• Simulation setting
• TCP
• packet size 1000 bytes window_ 20
• SCTP
• Data Chunk Size 1448 bytes MTU 1500 bytes
  outstream_number 1
• Simulation time 6.0 seconds
• 60 samples
• Metrics Total number of packets received by
  TCP/SCTP receiver

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Multihoming study

• Case 1 Change the primary address in the middle
  of an association
• SCTP Chunk size 1448 bytes MTU 1500 one
  HEARTBEAT is shared for all destination.
• Both nodes have two network interfaces.
• 20 second simulation switching happens at 15
  second
• Expected result
• The association should not be tear down between
  two SCTP nodes
• the normal data transfer should not be
  interrupted.

SCTP Sender
SCTP Receiver
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Multihoming study

• Case 2 SCTP vs. TCP for the network path failure
• SCTP host and TCP host share the same bottleneck
  network link
• SCTP
• SCTP Chunk size 1448 bytes MTU 1500 each
  destination has its own HEARTBEAT.
• Both nodes have two network interfaces.
• One TCP Agent and TCP Sink Agent
• 20 second simulation network failure between
  10, 15
• Expected result
• Continually delivering data for SCTP
• no data transfer using TCP during the network
  failure

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Alternate path for SCTP
Shared Bottleneck link
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TCP
SCTP
No data transfer during network failure 10, 15
During the network failure, SCTP using alternate
path to continually delivering data
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Conclusion and Future Work

• SCTPs multi-homing feature
• Learned a lot from this project
• In the future
• Study the flow control and congestion control
  mechanism of SCTP
• Investigate user-space SCTP reference
  implementation

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References

• SCTP RFC http//www.ietf.org/rfc/rfc2960.txt
• Randall Stewart and Qiaobing Xie, Stream Control
  Transmission Protocol (SCTP) A Reference,
  Publisher Addison-Wesley
• NS2 internet site http//www.isi.edu/nsnam/ns/ind
  ex.html
• NS2 SCTP patch internet site http//pel.cis.udel.
  edu/
• A.Jungmaier, M.Schopp, et al. - Performance
  Evaluation of the Stream Control transmission
  Protocol - Proceedings of the IEEE Conference on
  High Performance Switching and Routing, June
  2000.
• Rajesh Rajamani, S. Kumar, et al., SCTP versus
  TCP Comparing the Performance of Transport
  Protocols for Web Traffic, Computer Sciences
  Department, University of WisconsinMadison, May
  13, 2002
• A.Jungmaier, M.Schopp, et al SCTP A
  multi-link end-to-end protocol for IP-Based
  Networks International Journal of Electronics
  and Communications-2001
• SCTP in Battlefield networks - Phillip T. Conrad,
  Gerard J. Heinz - Computer and Information
  Science Department, Temple University,
  Philadelphia
• SCTP Web site http//www.sctp.de/sctp.html
• SCTP Web site http//www.sctp.org/index.html
• SCTP for Beginners http//tdrwww.exp-math.uni-ess
  en.de/pages/forschung/sctp_fb/
• Atifquzzaman, M., Performance of Stream Control
  Transmission Protocol (SCTP), PowerPoint slides,
  School of Computer Science, University of
  Oklahoma
• Chang D., and Grimm J., IBM Linux Technology
  Center, An Introduction to SCTP and the LKSCTP
  Project , PowerPoint slides
• Nicolas Christin, Build NS-2 on Cygwin,
  http//www.cs.virginia.edu/nc2y/ns-cygwin.shtml

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• ?

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Quiz

• The Signaling Transport group of IETF defines
  SCTP standards in _______
• A) RFC 2890
• B) RFC 2780
• C) RFC 2960
• D) RFC 2360
• In SCTP, data is transmitted only when a
  connection is established by creating a
  relationship, which is referred to as _______
• A link
• An association
• A collaboration
• An affiliation

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• SCTP closely monitors the transmission paths to
  the peer endpoint using _____ chunks that test
  the connectivity of each path.
• A) INIT
• B) SACK
• C) HEARTBEAT
• D) Shutdown
• The ______ feature enables SCTP endpoints to
  support multiple addresses.
• A) Chunk bundling
• B) multi-streaming
• C) address management
• D) multi-homing

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Thank You!