© introduction to internetworking – alex kooijman 04/04/2000 introduction to internetworking part...

© Introduction to Internetworking – Alex Kooijman04/04/2000

Introduction to internetworking

Part Two


Internet Protocol Suite

• IP and OSI/RM

• Internet Protocol

IP Packet

Type of Service

Address Resolution Protocol

• User Datagram Protocol

• Transmission Control Protocol

• IP addressing


Application

Presentation

Session

Transport

Network

Data Link

Physical

7

6

5

4

3

2

1

TCP

IP

UDP

6 17

23 21 25 69

telnet

ftp

smtp

tftp

IP and OSI/RM

IP = Internet ProtocolUDP = User Datagram Protocol


TIME TO LIVE PROTOCOL HEADER CHECKSUM

IDENTIFICATION

SERVICE TYPE

SOURCE IP ADDRESS

DESTINATION IP ADDRESS

IP OPTIONS (if any) PADDING

DATA

...

VERS HLEN TOTAL LENGTH

FRAGMENT OFFSET

0 4 8 16 19 24 31

FLAGS

IP Packet


Precedence Delay Througput Relialbility Cost MBZ

000 routine001 priority010 intermediate011 flash100 flash override101 critical110 internetwork control111 network control

0= normal1= low

0= normal1= high

0= normal1= low

0= normal1= high

0= normal1= high

IP Type of Service Field


10.16.69.56mac: 12345

10.16.69.205MAC: abcdeI want to connect to 10.16.69.205

what is the MAC address of 10.16.69.205?

Address Resolution Protocol (1)


10.16.69.56mac: 12345

10.16.69.205MAC: abcde

I am 10.16.69.205my MAC address is abcde

Address Resolution Protocol (2)


UDP uses no sequence or acknowledgment fields

UDP Datagram

SourcePort

Destination Port

Length Checksum Data

16 16 16


ACKNOWLEDGEMENT NUMBER

SEQUENCE NUMBER

SOURCE PORT

HLEN reserved CODE BITS

CHECKSUM URGENT POINTER

WINDOW

OPTIONS (if any) PADDING

DATA

...

DESTINATION PORT

0 4 10 16 24 31

TCP Segment


Send SYN (seq=100 ctl=SYN)

Host A Host B

1

TCP Three Way Handshake (1)



SYN received

Host A Host B

SYN received

1

2

Send SYN (seq=300 ack=101 ctl=syn,ack)




SYN received

Send SYN (seq=300 ack=101 ctl=syn,ack)

Send ACK(seq=101 ack=301 ctl=ack)

Host A Host B

SYN received

1

2

3

ACK receivedconnection is established



IP Addressing

• 32 bits represented in 4 decimal numbers, each representing 8 bits

• host part• network part• A, B, C, D, E class network numbers• two types of broadcast:

directed broadcast local network broadcast


32 Bits

IP Addressing

Class A : Network-part = 8 bits, Host-Part = 24 bitsClass B : Network-part = 16 bits, Host-Part = 16 bitsClass C : Network-part = 24 bits, Host-part = 8 bits

Class D : multicastClass E : experimental

Network part Host part


172.16.3.0/24

Broadcast to255.255.255.255

Notforwardedby router

172.16.4.0/24

172.16.5.0/24

IP Local Broadcast


Broadcast to172.16. 4.255

forwardedby router

172.16.3.0/24

172.16.4.0/24

172.16.5.0/24

IP Directed Broadcast


IP Subnetting

• Classless interdomain Routing (CIDR) route is known as address and mask supernetting and subnetting

• Variable Length Subnet Mask (VLSM) RFC1009 classfull networks can be split into multiple

networks with larger subnet masks


Class B Subnetting

# Bits Subnet Mask # Subnets # Hosts2 255.255.192.0 2 163823 255.255.224.0 6 81904 255.255.240.0 14 40945 255.255.248.0 30 20466 255.255.252.0 62 10227 255.255.254.0 126 5108 255.255.255.0 254 2549 255.255.255.128 510 12610 255.255.255.192 1022 6211 255.255.255.224 2046 3012 255.255.255.240 4094 1413 255.255.255.248 8190 614 255.255.255.252 16382 2

IP Subnetting


Internet Control Message Protocol

• Required on every IP stack• provides feedback about problems

time to live counter expires congestion failures destination not reachable

• direct into IP


Internet Control Message Protocol

• Messages: Echo request/reply Destination Unreachable Source quench Redirect Time Exceeded parameter problem timestamp request/reply information request/reply address mask request/reply

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