Download TCP/IP Overview

Chapter 4
TCP/IP Overview
People To
Information
Connecting Connecting
People
To
Information
Introduction to TCP/IP
Connecting People To Information
UNIX Host
UNIX Host
Internet
TCP/IP
• Early protocol suite
Introduction to TCP/IP
Connecting People To Information
UNIX Host
UNIX Host
Internet
TCP/IP
• Early protocol suite
• Universal
Connecting People To Information
Application Layer Overview
Application
Transport
Internet
Network
Interface
Hardware
File Transfer
- TFTP *
- FTP
- NFS
E-Mail
- SMTP
Remote Login
- Telnet *
- rlogin
Network Management
- SNMP *
Name Management
- DNS*
*Used by the router
Transport Layer
Connecting People To Information
Transport Layer Overview
Application
Transport
Internet
Network Interface
Hardware
Transmission Control
Protocol (TCP)
User Datagram
Protocol (UDP)
TCP Segment Format
Connecting People To Information
# Bits 16
Source
Port
16
32
Dest.
Port
Sequence
Number
32
Acknowledgement
Number
16
16
16
0 or 32
Window
Checksum
Urgent
Option
4
6
6
HLEN
Reserved
Code
Bits
Data...
Connecting People To Information
Port Numbers
Application
Layer
Transport
Layer
F
T
P
T
E
L
N
E
T
S
M
T
P
D
N
S
T
F
T
P
S
N
M
P
21
23
25
53
69
161
TCP
UDP
Port
Numbers
TCP Port Numbers
Connecting People To Information
Source
Port
Telnet Z
Dest.
Port
…
Host A
Host Z
SP
DP
1028
23
…
Dest. port = 23.
Send packet to my
Telnet
application.
TCP Handshake/Open
Connection
Connecting People To Information
Host A
1
Send SYN
(seq=100 ctl=SYN)
SYN received
3
Established
(seq=101 ack=301 ctl=ack)
4
Established
(seq=101 ack=301 ctl=ack
Data)
Host B
SYN received
2
Send SYN
(seq=300 ack=101 ctl=syn,ack)
TCP Simple Acknowledgment
Sender
Receiver
Connecting People To Information
Send 1
Receive 1
Send ACK 2
Receive ACK 2
Send 2
Receive 2
Send ACK 3
Receive ACK 3
Send 3
Receive 3
Send ACK 4
Receive ACK 4
• Window size = 1
TCP Windowing
Sender
Window size = 3
Send 1
Receiver
Connecting People To Information
Window size = 3
Send 2
Window size = 3
Send 3
ACK 1
Window size = 2
ACK 2
Window size = 2
ACK 3
Window size = 2
Window size = 3
Send 4
Window size = 3
Send 5
ACK 4
Window size = 2
ACK 5
Window size = 2
Connecting People To Information
TCP Sequence and
Acknowledgment Numbers
Source
Port
Dest.
Port
Sequence
#
Source Dest. Seq.
23
…
I just got #10,
now I need #11.
I just
sent #10.
1028
Acknowledgement
#
10
Ack.
1
…
Source Dest. Seq.
23
1028
1
Ack.
11
…
TCP Sequence and
Acknowledgment Numbers
Connecting People To Information
Source
Port
Dest.
Port
Sequence
#
I just
sent #10.
I just got #10,
now I need #11.
Source Dest. Seq.
1028
23
…
Acknowledgement
#
10
Ack.
1
…
Source Dest. Seq.
23
Source Dest. Seq.
1028
23
11
Ack.
2
…
1028
1
Ack.
11
…
UDP Segment Format
Connecting People To Information
# Bits
16
16
16
16
Source
Port
Destination
Port
Length
Checksum
Data…
• No sequence or acknowledgment fields
Internet Layer
Network Layer Overview
Internet Protocol (IP)
Connecting People To Information
Application
Transport
Internet
Internet Control Message
Protocol (ICMP)
Address Resolution
Protocol (ARP)
Network Interface
Hardware
Reverse Address
Resolution Protocol (RARP)
• OSI network layer corresponds to the
TCP/IP internet layer
IP Datagram
Connecting People To Information
# Bits 16
VERS
# Bits16
Protocol
16
32
HLEN
Type of
Service
32
Total
Length
4
4
6
6
Identification
Flags
Frag
Offset
TTL
16
32
32
4
4
Header
Checksum
Source IP
Address
Destination IP
Address
IP
Options
Data…
Protocol Field
Connecting People To Information
Transport
Layer
UDP
TCP
6
Internet
Layer
17
Protocol
Numbers
IP
• Determines destination upper-layer
protocol
Internet Control Message
Protocol
Connecting People To Information
Application
Transport
Destination
Unreachable
ICMP
Echo (Ping)
Internet
Network
Interface
Hardware
Other
ICMP Testing
Send data to Z.
I do not know how to get to Z.
Send ICMP.
Connecting People To Information
Host A
Data
Network
To Z
Destination Unreachable
• Destination unreachable
–Host or port unreachable
–Network unreachable
ICMP Testing (cont.)
Is B reachable?
Yes, I am here.
B
Connecting People To Information
A
ICMP Echo Request
ICMP Echo Reply
• Generated by the ping command
Reverse ARP
I heard that
broadcast.
Your IP
address is
172.16.3.25.
Connecting People To Information
What is my
IP
address?
Ethernet: 0800.0020.1111 IP = ???
Ethernet: 0800.0020.1111
IP: 172.16.3.25
• Map Ethernet
IP
• ARP and RARP are implemented directly on
top of the data link layer