chapter 4 tcp/ip overview connecting people to information
TRANSCRIPT
Chapter 4
TCP/IP Overview
Connecting People To InformationConnecting People To Information
Co
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ecti
ng
Pe
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o In
form
ati
on
• Early protocol suite
Introduction to TCP/IP
UNIX Host
Internet
TCP/IP
UNIX Host
Co
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ecti
ng
Pe
op
le T
o In
form
ati
on
• Early protocol suite
• Universal
Introduction to TCP/IP
UNIX Host
Internet
TCP/IP
UNIX Host
Co
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ecti
ng
Pe
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o In
form
ati
on
Application Layer Overview
*Used by the router
Application
Transport
Internet
Network Interface
Hardware
File Transfer- TFTP *- FTP- NFS
E-Mail- SMTP
Remote Login- Telnet *- rlogin
Network Management- SNMP *
Name Management- DNS*
File Transfer- TFTP *- FTP- NFS
E-Mail- SMTP
Remote Login- Telnet *- rlogin
Network Management- SNMP *
Name Management- DNS*
Transport Layer
Co
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Pe
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Transport Layer Overview
Transmission ControlProtocol (TCP)
User Datagram Protocol (UDP)
Transmission ControlProtocol (TCP)
User Datagram Protocol (UDP)
Application
Transport
Internet
Network Interface
Hardware
Co
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Pe
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TCP Segment Format# Bits 616 32 416 6 32
SourcePort
Dest.Port
SequenceNumber
AcknowledgementNumber
HLEN Reserved CodeBits
16
Window
16
Check-sum
16
Urgent
0 or 32
Option Data...
Co
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Port Numbers
TCP
Port Numbers
FTP
TransportLayer
TELNET
DNS
SNMP
TFTP
SMTP
UDP
ApplicationLayer
21 23 25 53 69 161
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TCP Port Numbers
SourcePort
Dest.Port
…
Host A
Dest. port = 23.
Send packet to my
Telnet
application.
1028 23 …
SP DP
Host ZTelnet Z
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TCP Handshake/Open Connection
Send SYN (seq=100 ctl=SYN)
SYN received
Send SYN (seq=300 ack=101 ctl=syn,ack)
Established(seq=101 ack=301 ctl=ack)
Host A Host B
Established(seq=101 ack=301 ctl=ack Data)
1
2
3
4
SYN received
Co
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• Window size = 1
Sender Receiver
Send 1Receive 1
Receive ACK 2 Send ACK 2
Send 2Receive 2
Receive ACK 3Send ACK 3
Send 3Receive 3
Receive ACK 4 Send ACK 4
TCP Simple Acknowledgment
Co
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Window size = 3Send 5
Window size = 3Send 2
TCP WindowingSender ReceiverWindow size = 3
Send 1
Window size = 3Send 4
Window size = 3Send 3
ACK 1Window size = 2
ACK 2Window size = 2
ACK 3Window size = 2
ACK 4Window size = 2
ACK 5Window size = 2
Co
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TCP Sequence and Acknowledgment Numbers
I justsent #10.
I just got #10,now I need #11.
Source
Port
Dest.
Port…Sequence
#
Acknowledgement
#
1028 23
Source Dest.
1010
Seq.
1
Ack.
…
102823Source Dest.
1111Seq.
1Ack.
…
Co
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Pe
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o In
form
ati
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TCP Sequence and Acknowledgment Numbers
I justsent #10.
I just got #10,now I need #11.
SourcePort
Dest.Port
…Sequence#
Acknowledgement#
1028 23
Source Dest.
1010
Seq.
1
Ack.
…
1028 23
Source Dest.
1111
Seq.
2
Ack.
…
102823
Source Dest.
1111
Seq.
1
Ack.
…
Co
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• No sequence or acknowledgment fields
UDP Segment Format
16Source
Port
16Destination
Port
16Length
16Checksum Data…
# Bits
Internet Layer
Co
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Pe
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Network Layer Overview
• OSI network layer corresponds to the TCP/IP internet layer
Internet Protocol (IP)
Internet Control MessageProtocol (ICMP)
Address ResolutionProtocol (ARP)
Reverse AddressResolution Protocol (RARP)
Internet Protocol (IP)
Internet Control MessageProtocol (ICMP)
Address ResolutionProtocol (ARP)
Reverse AddressResolution Protocol (RARP)
Application
Transport
Internet
Network Interface
Hardware
Co
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IP Datagram
# Bits 616 32 416 6 32
VERS HLEN Type ofService
TotalLength
Identi-fication
Flags FragOffset
TTL
4
# Bits 16 32 416 32
Protocol HeaderChecksum
Source IPAddress
Destination IPAddress
IPOptions
Data…
4
Co
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• Determines destination upper-layer protocol
Protocol Field
TransportLayer
InternetLayer
TCP UDP
ProtocolNumbers
IP
176
Co
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Internet Control Message Protocol
Application
Transport
Internet
Network Interface
Hardware
ICMP
Destination Unreachable
Echo (Ping)
Other
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ICMP Testing
• Destination unreachable–Host or port unreachable
–Network unreachable
Host AI do not know how to get to Z.
Send ICMP.
To Z
Destination Unreachable
Send data to Z.
DataNetwork
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ICMP Testing (cont.)
• Generated by the ping command
AYes, I am here.
ICMP Echo Reply
Is B reachable?
B
ICMP Echo Request
Co
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Reverse ARP
• Map Ethernet IP
• ARP and RARP are implemented directly on top of the data link layer
Ethernet: 0800.0020.1111IP: 172.16.3.25
Ethernet: 0800.0020.1111 IP = ???
What is my
IP
address?
I heard that
broadcast.
Your IP
address is
172.16.3.25.