Post on 31-Dec-2015
TCP/IP Basic Theory
V1.2
Course Outline
OSI model and layer function TCP/IP protocol suite Transfer Control Protocol Internet Protocol Address Resolution Protocol
N.Y. PekinTomJim
Post network
To Jim
Post code
Destination address
stamp
Post system
TCP/IP
First used protocol suite Universal De-facto standard Internet standard communication
Host A
Internet
TCP/IP
Host B
Data layer
Transport
Data link
Network
Physical
OSI Model
Upper layer
session
Presentation
Application Layer7
Layer6
Layer5
Layer4
Layer3
Layer2
Layer1
TelnetFTP
ASCIIEBCDICJPEG
Keep different applications independent Authentication
Example
Session
Upper Layer function
Network User InterfaceApplication
Presentation • Present data• Encryption, decryption
TCPUDPSPX
802.3 / 802.2HDLC
EIA/TIA-232V.35
IPIPX
Example
Data layer function
Transport
Network
Data Link
Physical
• Reliable and Unreliable transfer• Use retransmission to ensure reliability
• Combine bit to byte and byte to frame• Access media by MAC address• Error detection without error correction
Provide logical address and path-finding method for the working of routers
• Transfer bit between devices• Define voltage, bit rate, physical connection
Upper Layer Data
Upper Layer DataTCP Header
IP Header
0101110101001000010
MAC+LLC Header
Segment
Packet
Bits
Frame
PDU
FCS
Data Encapsulation
Transport
Data Link
Physical
Network
Presentation
Application
Session
Upper Layer Data
Upper Layer Data
Upper Layer Data
MAC+LLC Header IP + TCP + Upper Layer Data
TCP+ Upper Layer Data
IP Header
Upper Layer Data
TCP Header
0101110101001000010
Transport
Data Link
Physical
Network
Presentation
Application
Session
Data Decapsulation
Course Outline
OSI model and layer function TCP/IP protocol suite Transfer Control Protocol Internet Protocol Address Resolution Protocol
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Transport
Internet
Data Link
TCP/IP model vs OSI model
Application
Data Link
TCP
FTP
TELNET
DNS
TFTP
SMTP
UDP
21 23 25 53 69 161
IP176
SNMP
Application
Transport
Internet
Data Link
ARP ICMP
Ethernet II (RFC 894 )
080008061
TCP/IP Protocol Suite
Course Outline
OSI Model and Layer Function TCP/IP Protocol Suite Transfer Control Protocol Internet Protocol Address Resolution Protocol
Transport Layer
Segment upper layer data Establish end to end connection Ensure the reliability of data transfer
Logical connection
TCP Protocol
Source port (16) Destination port (16)
Sequence number (32)
Headerlength (4)
Acknowledgement number (32)
Reserved (6) Code bits (6) Window (16)
Checksum (16) Urgent (16)
Options (0 or 32 if any)
Data (varies)
20Bytes
Bit 0 Bit 15 Bit 16 Bit 31
well-known port number :1-1023 common port number: 1024-65535
Port Number range
Application
TCP
FTP
TELNET
DNS
TFTP
SMTP
UDP
21 23 25 53 69 161
SNMP
Application
Transport
Application
Transport
Internet
Data Link
Source Port Number
Destination Port Number
client
1028 23
SP DP
Telnet ZProcess #1
Port Number function
Destination port = 23Send packet to my
Telnet application
server
1029 23
Telnet ZProcess #2
Port multiplexing
Sender Receiver
Send 2Send 1
Send 3Ack 4
Send 5Send 4
Send 6Retransfer 5
Send 5Ack 7
1 2 3 4 5 6 1 2 3 4 5 6
Sequence and Ack Number
Code Bits
URG: Urgent Pointer field significant ACK: Acknowledgment field significant PSH: Push function RST: Reset the connection SYN: Synchronize sequence numbers FIN: No more data from sender
U
R
G
P
S
H
R
S
T
S
Y
N
F
I
N
A
C
K
Window size = 1
Send 1 Receive 1Ack 2
Send 2 Receive 2
Ack 3
Send 1
Send 2
Receive 1
Receive 2
Window size = 3
Send 3 Receive 3
Ack 4
Send 4
Sender Receiver
Sender Receiver
Window control
Establish connection (synchronize)
Data transfer (Send Segments)
Sender Receiver
Connection-oriented session
Tear down connection
1
3
2
TCP connection
Send SYN (seq=100 ctl=SYN) SYN received
Send SYN, ACK (seq=300 ack=101 ctl=SYN,ACK)
Established(seq=101 ack=301 ctl=ACK)
Host A Host B
1
2
3
SYN received
Establish Connection
TCP Three Way Handshake/Open Connection
Established
10281028 2323
Source Dest.
103103103103
Seq.
302302
Ack.
10281028 2323
Source Dest.
102102102102
Seq.
301301
Ack.
102810282323
Source Dest.
103103103103
Seq.
301301
Ack.
102810282323
Source Dest.
104104104104
Seq.
302302
Ack.
Data transfer
SP DP Seq. # Ack. #
Host A Host B
Upper layer data
ACK to FIN
ACK to FIN
FIN
FINClose application
Host A Host B
Close application
Tear down connection
TCP four way handshakes/connection terminating
1
2
3
4
UDP Protocol
No sequence and acknowledgement Unreliable and connectionless Efficient and fast
Source port (16) Destination port (16)
Length (16)
Data (if any)
Bit 0 Bit 15 Bit 16 Bit 31
Checksum (16)
8Bytes
TCP UDP
Connection oriented Or connectionless
Connection oriented
connectionless
Reliable or not Reliable unreliable
With traffic Control Or not Traffic control No traffic control
Transfer speed Slow Fast
overhead of protocol Big Small
TCP/UDP Comparison
Course Outline
OSI Model and Layer Function TCP/IP Protocol Suite Transfer Control Protocol Internet Protocol Address Resolution Protocol
Data Link
TCP UDP
IP176
Application
Transport
Internet
Data Link
ARP ICMP1
Internet/Network layer
Define logical address Provide path-finding method r
outers
IP packet format
Version(4)
Destination IP Address (32)
Options (0 or 32 if any)
Upper layer data (varies if any)
1Bit 0 Bit 15 Bit 16 Bit 31
HeaderLength (4)
Type of Service (8) Total Length (16)
Identification (16)Flags
(3) Fragment offset (13)
Time to live (8) Protocol (8) Header checksum (16)
Source IP Address (32)
20Bytes
Type of Service field
precedence D T R 0 0
Bits 0-2: PrecedenceBit 3: DelayBit 4: ThroughputBit 5: ReliabilityBits 6-7: Reserved for future use
0 3 7
MTU and fragmentation
0 15 16 17 18
Identification (16) Fragment offset (13)
Flags(3)
D
F0
M
F
Bit 16: Reserved, must be zero
Bit 17: (DF)0=May fragment, 1=Don’t fragment
Bit 18: (MF)0=Last fragment, 1=More fragmentHost A Host B
Ethernet
MTU 1000
IP(1500) HDLC IP(750)
HDLC IP(750)
Ethernet IP(750)
Ethernet IP(750)
RA RB
IP Address
Host A Host B
172.16.2.1 10.250.8.11172.16.2.1 10.6.24.2
Fei_1/1 Fei_1/2
255 255 255
DottedDecimal
Maximum
Network Host 255
128 64 32 16 8 4 2 1
11111111 11111111 11111111 11111111Binary
0 7 8 15 16 23 24 31
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
ICMP
Data LinkIP
Application
Transport
Internet
Data Link
ICMP1
Host A I am here.
ICMP echo reply
Hi B, are you there?
Host B
ICMP echo request
PING and reachability
Host or port unreachable Network unreachable
Destination Unreachable
Is B reachable?
ICMP echo request
no yes
Time Exceeded and TTL
Host A Host B
A: Tracert 10.1.1.2
1: 172.16.1.1
2: 200.1.1.2
3: 10.1.1.2
10.1.1.2
10.1.1.1
200.1.1.1200.1.1.2
172.16.1.2
172.16.1.1
RA RB
TTL=1
TTL=2
TTL=3
Course Outline
OSI Model and Layer Function TCP/IP Protocol Suite Transfer Control Protocol Internet Protocol Address Resolution Protocol
Data link Layer
Combine bit to byte and byte to frame
Access media by physical address (MAC address)
SAP associated with upper layer protocols type
Error detection without error correction
Data LinkIP
Application
Transport
Internet
Data Link
ARP ICMP
Ethernet II (RFC 894 )
080008061
DataSrc. Addr FCSTypeDest. Addr
Variable Length 46-1500266 4
00.d0.d0 xx.xx.xx
Sequence ID for NICIEEE assign toManufacturers
Ethernet II frame (RFC 894)
Preamble
8# Bytes
48-bits MAC Address
Address Resolution Protocol
Map IP to MAC Local broadcast
IP: 172.16.3.2 Ethernet: 0800.0020.1111 IP: 172.16.3.2 Ethernet: 0800.0020.1111
172.16.3.1 172.16.3.2
IP: 172.16.3.2 = ???IP: 172.16.3.2 = ???
I got the packet,I will reply with my MAC address.
I need the MAC address of IP 172.16.3.2
Host A Host B
Other hosts
Packet process procedure
FTP client
ftp://10.66.1.100:21 I wanna download a file
SP:1024 DP:21 Seq.100 Ack.200
FTP server
SIP:10.66.1.1 DIP:10.66.1.100,TTL=100, DF, Protocol=7
SA:01-00-39 DA:01-00-4A type=0800
01010010100010101010101010100010110111000101001
Summarization
OSI reference model TCP protocol suite Transport layer Network layer Data link layer