Marina Papatriantafilou – Transport layer part2 Based on the book Computer Networking: A Top Down Approach, Jim Kurose, Keith Ross, Addison-Wesley. Course.

Marina Papatriantafilou ndash Transport layer part2

Based on the book Computer Networking A Top Down Approach Jim Kurose Keith Ross Addison-Wesley

Course on Computer Communication and Networks

Lecture 5 Chapter 3 Transport Layer Part B

EDA344DIT 420 CTHGU

Marina Papatriantafilou ndash Transport layer part2 3b-3

Roadmap Transport Layer

bull transport layer servicesbull multiplexingdemultiplexingbull connectionless transport UDPbull principles of reliable data transferbull connection-oriented transport TCP

ndash reliable transferbull Acknowledgements bull Retransmissions bull Connection managementbull Flow control and buffer space

ndash Congestion controlbull Principlesbull TCP congestion control

Marina Papatriantafilou ndash Transport layer part2 3-4

TCP Overview RFCs 79311221323 2018 5681 full duplex data

bi-directional data flow in same connection

MSS maximum segment size

connection-oriented handshaking (exchange of control

msgs) inits sender amp receiver state before data exchange

flow control sender will not overwhelm

receiver

congestion control sender will not flood network with

traffic (but still try to maximize throughput)

bull point-to-pointndash one sender one receiver

bull reliable in-order byte steam

bull pipelinedndash TCP congestion and flow

control set window size

socketdoor

T C Psend buffer

T C Preceive buffer

socketdoor

segm ent

applicationwrites data

applicationreads data

TCP segment structure

dest port

32 bits

sequence number

acknowledgement number

receive window

Urg data pointerchecksum

FSRPAUheadlen

notused

options (variable length)

ACK ACK valid

URG urgent data (generally not used)

PSH push data now(generally not used)

RST SYN FINconnection estab(setup teardown

commands)

countingby bytes of data(not segments)

Internetchecksum

(as in UDP)

bytes rcvr willingto accept(flow control)

applicationdata (variable length)

source port

TCP seq numbers ACKs

sequence numbersndashldquonumberrdquo of first byte in

segmentrsquos dataacknowledgements

ndashseq of next byte expected from other side

ndashcumulative ACKsource port dest port

sequence number

checksum

incoming segment to sender

sent ACKed

sent not-yet ACKed(ldquoin-flightrdquo)

usablebut not yet sent

not usable

window size N

sender sequence number space

source port dest port

sequence number

checksum

outgoing segment from sender

Usertypes

lsquoCrsquo

host ACKs receipt

of echoed lsquoCrsquo

host ACKs receipt of lsquoCrsquo echoes back lsquoCrsquo

Simple example scenarioBased on telnet msg exchange

Host BHost A

Seq=42 ACK=79 data = lsquoCrsquo

Seq=43 ACK=80

Always ack next in-order expected byte

TCP cumulative Ack - retransmission scenarios

Cumulative ACK (Premature) timeout

Host BHost A

Seq=92 8 bytes of data

ACK=100

Seq=92 8bytes of data

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP ACK generation [RFC 1122 RFC 5681]

in-order segment arrival no gapseverything else already ACKed

in-order segment arrival no gapsone delayed ACK pending

out-of-order segment arrivalhigher-than-expect seq gap detected

arrival of segment that partially or completely fills gap

TCP Receiver action

Delayed ACK Wait up to 500msfor next segment If no next segmentsend ACK

immediately send singlecumulative ACK

send (duplicate) ACK indicating seq of next expected byte

immediate send ACK if segment startsat lower end of gap

Marina Papatriantafilou ndash Transport layer part2 13

applicationtransportnetwork

linkphysical

networklink

physical

segment

TCP round trip time timeout (1)

Q how to set TCP timeout value

longer than RTT but RTT varies

too short premature timeout unnecessary retransmissions

too long slow reaction to segment loss

EstimatedRTT = (1-)EstimatedRTT + SampleRTT

exponential weighted moving average influence of past sample decreases exponentially fast

typical value = 0125

DevRTT = (1-)DevRTT + |SampleRTT-EstimatedRTT|

(typically = 025)

TimeoutInterval = EstimatedRTT + 4DevRTT

estimated RTT ldquosafety marginrdquo

RTT gaiacsumassedu to fantasiaeurecomfr

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

)SampleRTT Estimated RTT

sampleRTTEstimatedRTT

time (seconds)

TCP fast retransmit (RFC 5681) time-out period often

relatively long long delay before resending lost

packet

IMPROVEMENT detect lost segments via duplicate ACKs

if sender receives 3 duplicate ACKs for same data

bull resend unacked segment with smallest seq

likely that unacked segment lost so donrsquot wait for timeout

TCP fast retransmit

Implicit NAKQ Why need at least 3

Host BHost A

ACK=100

Connection Managementbefore exchanging data senderreceiver ldquohandshakerdquobull agree to establish connection (each knowing the other willing

to establish connection)bull agree on connection parameters

connection state ESTABconnection variables

seq client-to-server server-to-clientrcvBuffer size at serverclient

application

network

connection state ESTABconnection Variables

application

network

Socket clientSocket = newSocket(hostnameport

number)

Socket connectionSocket = welcomeSocketaccept()

Marina Papatriantafilou ndash Transport layer part2 Transport Layer

Setting up a connection TCP 3-way handshake

SYN=1 Seq=x

choose init seq num xsend TCP SYN msg

SYN=1 Seq=yACK=1 ACKnum=x+1

choose init seq num ysend TCP SYNACKmsg acking SYNReserve buffer

ACK=1 ACKnum=y+1

received SYNACK(x) indicates server is livesend ACK for SYNACK

this segment may contain client-to-server data

received ACK(y) indicates client is live

SYNSENT

SYN RCVD

client state server state

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

ACK=1 ACKnum=x+1 wait for server

can stillsend data

can no longersend data

LAST_ACK

CLOSED

TIME_WAIT

timed wait (typically 30s)

CLOSED

TCP closing a connection

FIN_WAIT_1 FIN=1 seq=xcan no longersend but can receive data

clientSocketclose()

ESTABESTAB

simultaneous FINscan be handled

RST alternative way to close connection immediately when error occurs

Is TCP stateful or stateless

TCP flow controlapplicationprocess

TCP socketreceiver buffers

TCPcode

IPcode

application

receiver protocol stack

applicationmight remove data from

TCP socket buffers hellip

hellip slower than TCP is delivering

(ie slower than sender is sending)

from sender

receiver controls sender so sender wonrsquot overflow receiverrsquos buffer by transmitting too much too fast

flow control

TCP flow control

buffered data

free buffer spacerwnd

RcvBuffer

TCP segment payloads

to application process

bull receiver ldquoadvertisesrdquo free buffer space by including rwnd value in TCP header of receiver-to-sender segmentsndash RcvBuffer size set via

socket options (typical default is 4096 bytes)

ndash many operating systems autoadjust RcvBuffer

bull sender limits amount of unacked (ldquoin-flightrdquo) data to receiverrsquos rwnd value

bull guarantees receive buffer will not overflow

receiver-side buffering

sequence numberacknowledgement number

checksum

rwndATo sender

congestionbull informally ldquotoo many sources sending too much data

too fast for network to handlerdquobull manifestations

ndash lost packets (buffer overflow at routers)ndash long delays (queueing in router buffers)

Principles of congestion control

Need for flow control Need for congestion control

Fig A TanenbaumComputer Networks

Causescosts of congestion scenario 1 (unrealistic)

two senders two receivers average rate of data is lin

one router infinite buffers output link capacity R (no retransmission in the

ldquopicturerdquo yet)

maximum per-connection throughput R2

unlimited shared output link buffers

Host A

original data lin

Host B

throughput lout

lin R2d

large delays as arrival rate lin approaches capacity

when sending at R2 some packets are retransmissions including duplicated that are delivered

ldquocostsrdquo of congestion more work (retrans) for given ldquogoodputrdquo

(application-level throughput) unneeded retransmissions links carry multiple

copies of pkt

Causescosts of congestion scenario 2 Realistic buffers

bounded =gt duplicates

packets can be lost dropped at router due to full buffers

sender times out sending two copies

another cost of congestion when packets dropped any ldquoupstream

transmission capacity used for that packet was wasted

Causescosts of congestion scenario 3

linrsquo(incl Retransmisions)

Consider 4 streams

Approaches towards congestion control

two broad approaches towards congestion control

end-end congestion control

no explicit feedback from network

congestion inferred from end-system observed loss delay

approach taken by TCP

network-assisted congestion control

routers provide feedback to end systems eg a single bit indicating

congestion explicit rate for sender

to send at

TCP congestion control additive increase multiplicative decrease end-end control (no network assistance) sender limits transmissionHow does sender perceive congestion

loss = timeout or 3 duplicate acks TCP sender reduces rate (Congestion Window) then

Additive Increase increase cwnd by 1 MSS every RTT until loss detected Multiplicative Decrease cut cwnd in half after loss To start with slow start

AIMD saw toothbehavior probing

for bandwidth

additively increase window size helliphellip until loss occurs (then cut window in half)

rate ~~cwnd

RTTbytessec

TCP Slow Start

when connection begins increase rate exponentially until first loss event initially cwnd = 1 MSS double cwnd every RTT done by incrementing cwnd for

every ACK received

summary initial rate is slow but ramps up exponentially fast

Host A

one segment

Host B

two segments

four segments

Q when should the exponential increase switch to linear

A when cwnd gets to 12 of its value before timeout

Implementation variable ssthresh (slow start

threshold) on loss event ssthresh is set to

12 of cwnd just before loss event

TCP cwnd from exp to linear growth + reacting to loss

Reno loss indicated by timeout or 3 duplicate ACKscwnd is cut in half then grows linearly

Non-optimized loss indicated by timeoutcwnd set to 1 MSS window then grows as in slow start to threshold then grows linearly

fairness goal if K TCP sessions share same bottleneck link of bandwidth R each should have average rate of RK

TCP connection 1

bottleneckroutercapacity R

TCP Fairness

TCP connection 2

How many windows does a TCPrsquos sender maintain

TCP combined flow-ctrl congestion ctrl windows

sender limits transmission

cwnd is dynamic function of perceived network congestion rwnd dymanically limited by receiverrsquos buffer space

TCP sending rate roughly send min cwnd

rwnd bytes wait RTT for ACKS then send more bytes

Mincwnd rwnd

last byteACKed sent not-

yet ACKed(ldquoin-flightrdquo)

last byte sent

LastByteSent-LastByteAcked

lt Mincwnd rwnd

Chapter 3 summary

principles behind transport layer services Addressing reliable data transfer flow control congestion control

instantiation implementation in the Internet UDP TCP

nextbull leaving the network

ldquoedgerdquo (application transport layers)

bull into the network ldquocorerdquo

Some review questions on this part

bull Describe TCPrsquos flow controlbull Why does TCp do fast retransmit upon a 3rd ack and not a 2ndbull Describe TCPrsquos congestion control principle method for detection

of congestion reactionbull Can a TCPrsquos session sending rate increase indefinitelybull Why does TCP need connection managementbull Why does TCP use handshaking in the start and the end of

connectionbull Can an application have reliable data transfer if it uses UDP How or

why not

Reading instructions chapter 3

bull KuroseRoss book

bull Other resources (further study)ndash Eddie Kohler Mark Handley and Sally Floyd 2006 Designing DCCP congestion

control without reliability SIGCOMM Comput Commun Rev 36 4 (August 2006) 27-38 DOI=10114511516591159918 httpdoiacmorg10114511516591159918

ndash httpresearchmicrosoftcomappsvideodefaultaspxid=104005

ndash Exercisethroughput analysis TCP in following slides

Careful Quick

31 32 34-37 33

Extra slides for further study

3 Transport Layer 3b-45

TCP throughput

bull avg TCP throughput as function of window size RTTndash ignore slow start assume always data to send

bull W window size (measured in bytes) where loss occursndash avg window size ( in-flight bytes) is frac34 Wndash avg trhoughput is 34W per RTT

avg TCP trhoughput = 34

WRTTbytessec

TCP Futures TCP over ldquolong fat pipesrdquo

bull example 1500 byte segments 100ms RTT want 10 Gbps throughput

bull requires W = 83333 in-flight segmentsbull throughput in terms of segment loss probability L

[Mathis 1997]

to achieve 10 Gbps throughput need a loss rate of L = 210-10 ndash a very small loss rate

bull new versions of TCP for high-speed

TCP throughput = 122 MSSRTT L

Why is TCP fair

two competing sessions additive increase gives slope of 1 as throughout increases multiplicative decrease decreases throughput proportionally

equal bandwidth share

Connection 1 throughput

h pu t

congestion avoidance additive increaseloss decrease window by factor of 2

Fairness (more)

Fairness and UDPmultimedia apps often

do not use TCP do not want rate

throttled by congestion control

instead use UDP send audiovideo at

constant rate tolerate packet loss

Fairness parallel TCP connections

application can open multiple parallel connections between two hosts

web browsers do this eg link of rate R with 9

existing connections new app asks for 1 TCP gets rate

R10 new app asks for 11 TCPs gets R2

Marina Papatriantafilou ndash Transport layer part2 3 Transport Layer 3b-50

TCP delay modeling (slow start ndash related)

Q How long does it take to receive an object from a Web server after sending a request

bull TCP connection establishmentbull data transfer delay

Notation assumptionsbull Assume one link between client

and server of rate Rbull Assume fixed congestion

window W segmentsbull S MSS (bits)bull O object size (bits)bull no retransmissions (no loss no

corruption)bull Receiver has unbounded buffer

TCP delay Modeling simplified fixed window

Case 1 WSR gt RTT + SR ACK for first segment in window returns before windowrsquos worth of data nsentdelay = 2RTT + OR

Case 2 WSR lt RTT + SR wait for ACK after sending windowrsquos worth of data sentdelay = 2RTT + OR+ (K-1)[SR + RTT - WSR]

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

TCP Delay Modeling Slow Start

initia te TCPconnection

requestobject

first w indow= S R

second w indow= 2S R

third w indow= 4S R

fourth w indow= 8S R

com pletetransm issionobject

delivered

tim e atc lient

tim e atserver

Examplebull OS = 15 segmentsbull K = 4 windowsbull Q = 2bull Server idles P = minK-1Q = 2 times

Delay componentsbull 2 RTT for connection estab and requestbull OR to transmit objectbull time server idles due to slow start

Server idles P = minK-1Q times

where - Q = times server stalls until cong window is larger than a ldquofull-utilizationrdquo window (if the object were of unbounded size)

- K = (incremental-sized) congestion-windows that ldquocoverrdquo the object

TCP Delay Modeling (slow start - cont)

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

th window after the timeidle 2 1 kR

ementacknowledg receivesserver until

segment send tostartsserver whenfrom time RTTR

window kth the transmit totime2 1

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

Calculation of Q number of idles for infinite-size objectis similar

Recall K = number of windows that cover object

How do we calculate K

Course on Computer Communication and Networks Lecture 5 Chap

TCP Overview RFCs 79311221323 2018 5681

Roadmap Transport Layer (2)

TCP seq numbers ACKs (2)

TCP fast retransmit (RFC 5681)

Connection Management

TCP flow control

TCP flow control (2)

TCP congestion control additive increase multiplicative decre

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

receiver

socketdoor

T C Psend buffer

T C Preceive buffer

socketdoor

segm ent

dest port

32 bits

sequence number

receive window

FSRPAUheadlen

notused

ACK ACK valid

commands)

Internetchecksum

(as in UDP)

source port

sequence number

checksum

sent ACKed

not usable

window size N

sequence number

checksum

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

receiver

socketdoor

T C Psend buffer

T C Preceive buffer

socketdoor

segm ent

dest port

32 bits

sequence number

receive window

FSRPAUheadlen

notused

ACK ACK valid

commands)

Internetchecksum

(as in UDP)

source port

sequence number

checksum

sent ACKed

not usable

window size N

sequence number

checksum

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

dest port

32 bits

sequence number

receive window

FSRPAUheadlen

notused

ACK ACK valid

commands)

Internetchecksum

(as in UDP)

source port

sequence number

checksum

sent ACKed

not usable

window size N

sequence number

checksum

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

sequence number

checksum

sent ACKed

not usable

window size N

sequence number

checksum

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

sequence number

checksum

sent ACKed

not usable

window size N

sequence number

checksum

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Usertypes

lsquoCrsquo

host ACKs receipt

Host BHost A

Seq=43 ACK=80

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Host BHost A

ACK=100

ACK=120

SendBase=100

SendBase=120

SendBase=92

Host BHost A

ACK=100

ACK=120

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP Receiver action

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

linkphysical

networklink

physical

segment

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

(typically = 025)

1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106

time (seconnds)

time (seconds)

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

packet

TCP fast retransmit

Host BHost A

ACK=100

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

application

network

application

network

number)

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

SYN=1 Seq=x

ACK=1 ACKnum=y+1

SYNSENT

SYN RCVD

LISTEN

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

FIN_WAIT_2

CLOSE_WAIT

FIN=1 seq=y

ACK=1 ACKnum=y+1

can stillsend data

LAST_ACK

CLOSED

TIME_WAIT

CLOSED

clientSocketclose()

ESTABESTAB

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCPcode

IPcode

application

from sender

flow control

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP flow control

buffered data

RcvBuffer

checksum

rwndATo sender

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Host A

original data lin

Host B

throughput lout

lin R2d

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

copies of pkt

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Consider 4 streams

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

to send at

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

for bandwidth

rate ~~cwnd

RTTbytessec

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP Slow Start

every ACK received

Host A

one segment

Host B

two segments

four segments

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP connection 1

TCP Fairness

TCP connection 2

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Mincwnd rwnd

last byte sent

lt Mincwnd rwnd

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Chapter 3 summary

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

why not

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Careful Quick

31 32 34-37 33

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

TCP throughput

WRTTbytessec

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

[Mathis 1997]

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Why is TCP fair

h pu t

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Fairness (more)

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

K= OWS

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

SRTTPRTT

idleTimeRTTR

)12(][2

2delay

requestobject

first w indow= S R

third w indow= 4S R

delivered

tim e atc lient

tim e atserver

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

)1(log

)1(logmin

222min

OSSSkK

TCP flow control

TCP Slow Start

TCP Fairness

Chapter 3 summary

TCP throughput

Why is TCP fair

Fairness (more)

TCP Delay Modeling

Marina Papatriantafilou – Transport layer part2 Based on the book Computer Networking: A Top Down Approach, Jim Kurose, Keith Ross, Addison-Wesley. Course.

Documents

bytes of data

data exchange flow control

urgent data

duplex data

bidirectional data flow

segments data acknowledgements

receiver congestion

tcp udp