SlideShare a Scribd company logo
1 of 31
The Transport Layer
Chapter 6
The Transport Service
a) Services Provided to the Upper Layers
b) Transport Service Primitives
c) Berkeley Sockets
Services Provided to the Upper Layers
The network, transport, and application layers.
Why the transport layer ?
1. The network layer exists on end hosts and routers in the
network. The end-user cannot control what is in the network. So
the end-user establishes another layer, only at end hosts, to
provide a transport service that is more reliable than the
underlying network service.
2. While the network layer deals with only a few transport
entities, the transport layer allows several concurrent applications
to use the transport service.
3. It provides a common interface to application writers,
regardless of the underlying network layer. In essence, an
application writer can write code once using the transport layer
primitive and use it on different networks (but with the same
transport layer).
Transport Service Primitives
The primitives for a simple transport service.
Transport Service Primitives (2)
The nesting of TPDUs, packets, and frames.
Transport Service Primitives (3)
A state diagram for a simple connection management scheme.
Transitions labelled in italics are caused by packet arrivals. The
solid lines show the client's state sequence. The dashed lines show
the server's state sequence.
Berkeley Sockets
The socket primitives for TCP.
Elements of Transport Protocols
a) Addressing
b) Connection Establishment
c) Connection Release
d) Flow Control and Buffering
e) Multiplexing
f) Crash Recovery
Transport Protocol
(a) Environment of the data link layer.
(b) Environment of the transport layer.
Both data link layer and transport layer do error control, flow control,
sequencing. The differences are:
1. Storage capacity in subnet. Frames must arrive sequentially,
TPDUs can arrive in any sequence.
2. Frames are delivered to hosts, TPDUs need to be delivered to
users, so per user addressing and flow control within the hosts is
necessary.
Addressing
TSAPs (Transport Service Access Point) , NSAPs (Network SAP).
TCP calls TSAP s ... ports
ATM calls TSAPs ... AAL-SAP
Connection Establishment (1)
How a user process in host 1 establishes a connection
with a time-of-day server in host 2.
Connection Establishment (2)
Three protocol scenarios for establishing a connection using a
three-way handshake. CR denotes CONNECTION REQUEST.
(a) Normal operation,
(b) Old CONNECTION REQUEST appearing out of nowhere.
(c) Duplicate CONNECTION REQUEST and duplicate ACK.
Connection Establishment (3)
(a) TPDUs may not enter the forbidden region.
(b) The resynchronization problem.
Connection Release
Abrupt disconnection with loss of data.
Connection Release (2)
The two-army problem.
Connection Release (3)
Four protocol scenarios for releasing a connection. (a) Normal case of a
three-way handshake. (b) final ACK lost.
6-14, a, b
Connection Release (4)
(c) Response lost. (d) Response lost and subsequent DRs lost.
6-14, c,d
Flow Control and Buffering
Dynamic buffer allocation. Buffer allocation info travels in separate TPDUs.
The arrows show the direction of transmission. ‘…’ indicates a lost TPDU.
Potential deadlock if control TPDUs are not sequenced or timed out
Multiplexing
(a) Upward multiplexing.
(b) Downward multiplexing. Used to increase the bandwidth, e.g., two
ISDN connections of 64 kbps each yield 128 kbps bandwidth.
The Internet Transport Protocols: UDP
• Introduction to UDP
• Remote Procedure Call
• The Real-Time Transport Protocol
Introduction to UDP
The UDP header.
UDP only provides TSAPs (ports) for applications to bind to. UDP
does not provide reliable or ordered service. The checksum is
optional.
Remote Procedure Call
Steps in making a remote procedure call. The stubs are shaded.
The Real-Time Transport Protocol
(a) The position of RTP in the protocol stack. (b) Packet nesting.
The Real-Time Transport Protocol (2)
The RTP header. X indicated the presence of an extension header.
CC says how many contributing sources are present (0 to 15).
Syn. Source Id. tells which stream the packet belongs to.
For feedback information is used an associated protocol called
RTCP (Real Time Control Protocol)
The Internet Transport Protocols: TCP
a) Introduction to TCP
b) The TCP Service Model
c) The TCP Protocol
d) The TCP Segment Header
e) TCP Connection Establishment
f) TCP Connection Release
g) TCP Connection Management Modeling
h) TCP Transmission Policy
i) TCP Congestion Control
j) TCP Timer Management
k) Wireless TCP and UDP
l) Transactional TCP
The TCP Service Model
Some assigned ports.
Port Protocol Use
21 FTP File transfer
23 Telnet Remote login
25 SMTP E-mail
69 TFTP Trivial File Transfer Protocol
79 Finger Lookup info about a user
80 HTTP World Wide Web
110 POP-3 Remote e-mail access
119 NNTP USENET news
The TCP Service Model (2)
(a) Four 512-byte segments sent as separate IP datagrams.
(b) The 2048 bytes of data delivered to the application in a single
READ CALL.
TCP Service Model (3)
All TCP connections are full-duplex and point-to-point.
TCP provides a byte stream. i.e it does not preserve message
boundaries
At sender TCP may immediately send or buffer data at its
discretion.
Sender can use a PUSH flag to instruct TCP not to buffer the
send.
Sender can use URGENT flag to have TCP send data
immediately and have the receiver TCP signal the receiver
application that there is data to be read.
Some TCP features
Every byte has its own 32 bit sequence number.
Sending and receiving entities exchange data in segments
Each segment is the 20 byte header and data (total up to 64K)
TCP may aggregate multiple writes into one segment or split one
write into several segments.
A segment size if the smaller of either 64K or the MTU of the
network layer (MTU of Ethernet is about 1500 bytes)
A segment must fit in a single IP payload.
Some TCP features
TCP uses the sliding window protocol as its base.
Sender sends segment, starts timer waits for ack. It no ack then
retransmit. Receiver acks in separate segment or “piggyback” on
data segment.
TCP must deal with reordred segments.
A lot of algorithms have been developed to make TCP efficient
under diverse network conditions. We will look at a few of them.

More Related Content

Similar to Transport layer issues and challenges - Guide

Iaetsd an effective approach to eliminate tcp incast
Iaetsd an effective approach to eliminate tcp incastIaetsd an effective approach to eliminate tcp incast
Iaetsd an effective approach to eliminate tcp incast
Iaetsd Iaetsd
 

Similar to Transport layer issues and challenges - Guide (20)

Transport layer
Transport layer Transport layer
Transport layer
 
Unit 4 tansport layer in the internat
Unit 4 tansport layer in the internatUnit 4 tansport layer in the internat
Unit 4 tansport layer in the internat
 
TCP Vs UDP
TCP Vs UDP TCP Vs UDP
TCP Vs UDP
 
Week10 transport
Week10 transportWeek10 transport
Week10 transport
 
MK-PPT Chapter 5.ppt advanced computer networks
MK-PPT Chapter 5.ppt advanced computer networksMK-PPT Chapter 5.ppt advanced computer networks
MK-PPT Chapter 5.ppt advanced computer networks
 
Transport layer.pptx
Transport layer.pptxTransport layer.pptx
Transport layer.pptx
 
IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...
IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...
IMPACT OF CONTENTION WINDOW ON CONGESTION CONTROL ALGORITHMS FOR WIRELESS ADH...
 
ch5-network.ppt
ch5-network.pptch5-network.ppt
ch5-network.ppt
 
Answer sheet of switching & routing
Answer sheet of switching & routingAnswer sheet of switching & routing
Answer sheet of switching & routing
 
Unit 5.Transport Layer.pptx
Unit 5.Transport Layer.pptxUnit 5.Transport Layer.pptx
Unit 5.Transport Layer.pptx
 
Transport layer
Transport layerTransport layer
Transport layer
 
Transport layer
Transport layerTransport layer
Transport layer
 
Polyraptor
PolyraptorPolyraptor
Polyraptor
 
Chapter03 sg
Chapter03 sgChapter03 sg
Chapter03 sg
 
Tcp
TcpTcp
Tcp
 
Iaetsd an effective approach to eliminate tcp incast
Iaetsd an effective approach to eliminate tcp incastIaetsd an effective approach to eliminate tcp incast
Iaetsd an effective approach to eliminate tcp incast
 
Transport_Layer (1).pptx
Transport_Layer (1).pptxTransport_Layer (1).pptx
Transport_Layer (1).pptx
 
Computer Network - Network Layer
Computer Network - Network LayerComputer Network - Network Layer
Computer Network - Network Layer
 
CCNA Interview.pdf
CCNA Interview.pdfCCNA Interview.pdf
CCNA Interview.pdf
 
Mcseminar
McseminarMcseminar
Mcseminar
 

Recently uploaded

一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
tuuww
 
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdfONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
Kamal Acharya
 
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdfDR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
DrGurudutt
 
Digital Signal Processing Lecture notes n.pdf
Digital Signal Processing Lecture notes n.pdfDigital Signal Processing Lecture notes n.pdf
Digital Signal Processing Lecture notes n.pdf
AbrahamGadissa
 

Recently uploaded (20)

一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
一比一原版(UNK毕业证)内布拉斯加州立大学科尼分校毕业证成绩单
 
Electrostatic field in a coaxial transmission line
Electrostatic field in a coaxial transmission lineElectrostatic field in a coaxial transmission line
Electrostatic field in a coaxial transmission line
 
Dairy management system project report..pdf
Dairy management system project report..pdfDairy management system project report..pdf
Dairy management system project report..pdf
 
2024 DevOps Pro Europe - Growing at the edge
2024 DevOps Pro Europe - Growing at the edge2024 DevOps Pro Europe - Growing at the edge
2024 DevOps Pro Europe - Growing at the edge
 
Electrical shop management system project report.pdf
Electrical shop management system project report.pdfElectrical shop management system project report.pdf
Electrical shop management system project report.pdf
 
Furniture showroom management system project.pdf
Furniture showroom management system project.pdfFurniture showroom management system project.pdf
Furniture showroom management system project.pdf
 
BRAKING SYSTEM IN INDIAN RAILWAY AutoCAD DRAWING
BRAKING SYSTEM IN INDIAN RAILWAY AutoCAD DRAWINGBRAKING SYSTEM IN INDIAN RAILWAY AutoCAD DRAWING
BRAKING SYSTEM IN INDIAN RAILWAY AutoCAD DRAWING
 
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdfONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
ONLINE VEHICLE RENTAL SYSTEM PROJECT REPORT.pdf
 
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdfDR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
DR PROF ING GURUDUTT SAHNI WIKIPEDIA.pdf
 
RM&IPR M5 notes.pdfResearch Methodolgy & Intellectual Property Rights Series 5
RM&IPR M5 notes.pdfResearch Methodolgy & Intellectual Property Rights Series 5RM&IPR M5 notes.pdfResearch Methodolgy & Intellectual Property Rights Series 5
RM&IPR M5 notes.pdfResearch Methodolgy & Intellectual Property Rights Series 5
 
Natalia Rutkowska - BIM School Course in Kraków
Natalia Rutkowska - BIM School Course in KrakówNatalia Rutkowska - BIM School Course in Kraków
Natalia Rutkowska - BIM School Course in Kraków
 
ENERGY STORAGE DEVICES INTRODUCTION UNIT-I
ENERGY STORAGE DEVICES  INTRODUCTION UNIT-IENERGY STORAGE DEVICES  INTRODUCTION UNIT-I
ENERGY STORAGE DEVICES INTRODUCTION UNIT-I
 
RESORT MANAGEMENT AND RESERVATION SYSTEM PROJECT REPORT.pdf
RESORT MANAGEMENT AND RESERVATION SYSTEM PROJECT REPORT.pdfRESORT MANAGEMENT AND RESERVATION SYSTEM PROJECT REPORT.pdf
RESORT MANAGEMENT AND RESERVATION SYSTEM PROJECT REPORT.pdf
 
Construction method of steel structure space frame .pptx
Construction method of steel structure space frame .pptxConstruction method of steel structure space frame .pptx
Construction method of steel structure space frame .pptx
 
KIT-601 Lecture Notes-UNIT-3.pdf Mining Data Stream
KIT-601 Lecture Notes-UNIT-3.pdf Mining Data StreamKIT-601 Lecture Notes-UNIT-3.pdf Mining Data Stream
KIT-601 Lecture Notes-UNIT-3.pdf Mining Data Stream
 
Pharmacy management system project report..pdf
Pharmacy management system project report..pdfPharmacy management system project report..pdf
Pharmacy management system project report..pdf
 
retail automation billing system ppt.pptx
retail automation billing system ppt.pptxretail automation billing system ppt.pptx
retail automation billing system ppt.pptx
 
RM&IPR M4.pdfResearch Methodolgy & Intellectual Property Rights Series 4
RM&IPR M4.pdfResearch Methodolgy & Intellectual Property Rights Series 4RM&IPR M4.pdfResearch Methodolgy & Intellectual Property Rights Series 4
RM&IPR M4.pdfResearch Methodolgy & Intellectual Property Rights Series 4
 
Digital Signal Processing Lecture notes n.pdf
Digital Signal Processing Lecture notes n.pdfDigital Signal Processing Lecture notes n.pdf
Digital Signal Processing Lecture notes n.pdf
 
Software Engineering - Modelling Concepts + Class Modelling + Building the An...
Software Engineering - Modelling Concepts + Class Modelling + Building the An...Software Engineering - Modelling Concepts + Class Modelling + Building the An...
Software Engineering - Modelling Concepts + Class Modelling + Building the An...
 

Transport layer issues and challenges - Guide

  • 2. The Transport Service a) Services Provided to the Upper Layers b) Transport Service Primitives c) Berkeley Sockets
  • 3. Services Provided to the Upper Layers The network, transport, and application layers.
  • 4. Why the transport layer ? 1. The network layer exists on end hosts and routers in the network. The end-user cannot control what is in the network. So the end-user establishes another layer, only at end hosts, to provide a transport service that is more reliable than the underlying network service. 2. While the network layer deals with only a few transport entities, the transport layer allows several concurrent applications to use the transport service. 3. It provides a common interface to application writers, regardless of the underlying network layer. In essence, an application writer can write code once using the transport layer primitive and use it on different networks (but with the same transport layer).
  • 5. Transport Service Primitives The primitives for a simple transport service.
  • 6. Transport Service Primitives (2) The nesting of TPDUs, packets, and frames.
  • 7. Transport Service Primitives (3) A state diagram for a simple connection management scheme. Transitions labelled in italics are caused by packet arrivals. The solid lines show the client's state sequence. The dashed lines show the server's state sequence.
  • 8. Berkeley Sockets The socket primitives for TCP.
  • 9. Elements of Transport Protocols a) Addressing b) Connection Establishment c) Connection Release d) Flow Control and Buffering e) Multiplexing f) Crash Recovery
  • 10. Transport Protocol (a) Environment of the data link layer. (b) Environment of the transport layer. Both data link layer and transport layer do error control, flow control, sequencing. The differences are: 1. Storage capacity in subnet. Frames must arrive sequentially, TPDUs can arrive in any sequence. 2. Frames are delivered to hosts, TPDUs need to be delivered to users, so per user addressing and flow control within the hosts is necessary.
  • 11. Addressing TSAPs (Transport Service Access Point) , NSAPs (Network SAP). TCP calls TSAP s ... ports ATM calls TSAPs ... AAL-SAP
  • 12. Connection Establishment (1) How a user process in host 1 establishes a connection with a time-of-day server in host 2.
  • 13. Connection Establishment (2) Three protocol scenarios for establishing a connection using a three-way handshake. CR denotes CONNECTION REQUEST. (a) Normal operation, (b) Old CONNECTION REQUEST appearing out of nowhere. (c) Duplicate CONNECTION REQUEST and duplicate ACK.
  • 14. Connection Establishment (3) (a) TPDUs may not enter the forbidden region. (b) The resynchronization problem.
  • 16. Connection Release (2) The two-army problem.
  • 17. Connection Release (3) Four protocol scenarios for releasing a connection. (a) Normal case of a three-way handshake. (b) final ACK lost. 6-14, a, b
  • 18. Connection Release (4) (c) Response lost. (d) Response lost and subsequent DRs lost. 6-14, c,d
  • 19. Flow Control and Buffering Dynamic buffer allocation. Buffer allocation info travels in separate TPDUs. The arrows show the direction of transmission. ‘…’ indicates a lost TPDU. Potential deadlock if control TPDUs are not sequenced or timed out
  • 20. Multiplexing (a) Upward multiplexing. (b) Downward multiplexing. Used to increase the bandwidth, e.g., two ISDN connections of 64 kbps each yield 128 kbps bandwidth.
  • 21. The Internet Transport Protocols: UDP • Introduction to UDP • Remote Procedure Call • The Real-Time Transport Protocol
  • 22. Introduction to UDP The UDP header. UDP only provides TSAPs (ports) for applications to bind to. UDP does not provide reliable or ordered service. The checksum is optional.
  • 23. Remote Procedure Call Steps in making a remote procedure call. The stubs are shaded.
  • 24. The Real-Time Transport Protocol (a) The position of RTP in the protocol stack. (b) Packet nesting.
  • 25. The Real-Time Transport Protocol (2) The RTP header. X indicated the presence of an extension header. CC says how many contributing sources are present (0 to 15). Syn. Source Id. tells which stream the packet belongs to. For feedback information is used an associated protocol called RTCP (Real Time Control Protocol)
  • 26. The Internet Transport Protocols: TCP a) Introduction to TCP b) The TCP Service Model c) The TCP Protocol d) The TCP Segment Header e) TCP Connection Establishment f) TCP Connection Release g) TCP Connection Management Modeling h) TCP Transmission Policy i) TCP Congestion Control j) TCP Timer Management k) Wireless TCP and UDP l) Transactional TCP
  • 27. The TCP Service Model Some assigned ports. Port Protocol Use 21 FTP File transfer 23 Telnet Remote login 25 SMTP E-mail 69 TFTP Trivial File Transfer Protocol 79 Finger Lookup info about a user 80 HTTP World Wide Web 110 POP-3 Remote e-mail access 119 NNTP USENET news
  • 28. The TCP Service Model (2) (a) Four 512-byte segments sent as separate IP datagrams. (b) The 2048 bytes of data delivered to the application in a single READ CALL.
  • 29. TCP Service Model (3) All TCP connections are full-duplex and point-to-point. TCP provides a byte stream. i.e it does not preserve message boundaries At sender TCP may immediately send or buffer data at its discretion. Sender can use a PUSH flag to instruct TCP not to buffer the send. Sender can use URGENT flag to have TCP send data immediately and have the receiver TCP signal the receiver application that there is data to be read.
  • 30. Some TCP features Every byte has its own 32 bit sequence number. Sending and receiving entities exchange data in segments Each segment is the 20 byte header and data (total up to 64K) TCP may aggregate multiple writes into one segment or split one write into several segments. A segment size if the smaller of either 64K or the MTU of the network layer (MTU of Ethernet is about 1500 bytes) A segment must fit in a single IP payload.
  • 31. Some TCP features TCP uses the sliding window protocol as its base. Sender sends segment, starts timer waits for ack. It no ack then retransmit. Receiver acks in separate segment or “piggyback” on data segment. TCP must deal with reordred segments. A lot of algorithms have been developed to make TCP efficient under diverse network conditions. We will look at a few of them.