1

OSI Seven Layer

A B

Router 1 Router 2Session

Application Application

PressentationPressentation

Session

TransportTransport

Network Network Network Network

Data LinkData LinkData Link Data Link

Physical PhysicalPhysical Physical

2

Physical Layer(1)

1 0100 11

+6 V

0 V

3

Physical Layer(2) RS-232C

0 10 11

+V

-V

00 1

Data bits End bitStart bit

0 1 2 3 4 5 6 7

4

Physical Layer(3) Manchester

0 11 10

+V

-V

01 1

bit duration

010

5

Physical Layer(4) Differential Manchester

0. Signal voltage changes in the middle of the bit ； Signal voltage changes in the beginning of the bit

1. Signal voltage changes in the middle of the bit ； Signal voltage do not change in the beginning

Control Signal voltage do not change in the middle of the bit

0 10 01

+V

-V

10 1 111

6

Data Link Layer

MAC information:

http://map-ne.com/Ethernet/vendor.html

7

Some of the Routing Protocols:

RIP RIPv2 OSPF IGRP EIGRP IS-IS BGP

Network Layer

8

Routed Protocols ：

IP IPX

Apple Talk

DecNET

Network Layer

9

Network Layer Address ：  

Hierarchical

Network Number Host Number

Logical Address

MAC Address ：  

Flat

Physical Address

Network Layer

10

TCP/IP Model

DOD Reference Model OSI Model

Application Presentation Process/Application Session

Host-to-Host Transport

Internet Network

Data Link Network Access Physical

11

TCP/IP Model

Telnet FTP LPD SNMP

Process/ Application TFTP SMTP NFS X window

Host-to-Host TCP UDP

ICMP BootP ARP RARP Internet IP

Network Access Ethernet

Fast Ethernet

Token Ring

FDDI

12

TCP/IP Model

IEEE 802 Standard

802.1 Higher Layer LAN Protocols Working Group

802.2 Logical Link Control Working Group (Inactive)

802.3 Ethernet Working Group

802.4 Token Bus Working Group (Inactive)

802.5 Token Ring Working Group

802.6 Metropolitan Area Network Working Group (Inactive)

802.7 Broadband TAG (Inactive)

13

TCP/IP Model

802.8 Fiber Optic TAG

802.9 Isochronous LAN Working Group

802.10 Security Working Group

802.11 Wireless LAN Working Group

802.12 Demand Priority Working Group

802.13 Not Used

IEEE 802 Standard(Cont’d)

14

TCP/IP Model

802.14 Cable Modem Working Group (Archive information is currently being moved, not available)

802.15 Wireless Personal Area Network (WPAN) Working Group

802.16 Broadband Wireless Access Working Group

802.17 Resilient Packet Ring Working Group

IEEE 802 Standard(Cont’d)

http://grouper.ieee.org/groups/802/dots.html

15

Summary

OSI Model Functions:

Compression/Decompression

Encryption/Decryption

Connection Establishing/Terminating

Segmentation/Reassembly

Flow Control

Error Control

Addressing/Routing

16

Summary

OSI Model Functions: (Cont’d)

Sequencing

Encapsulation/Decapsulation

Encoding/Decoding

Multiplexing

Synchronization

Positive Acknowledgement and Retransmission (PAR)

Windowing

17

Internet ProtocolFirst Octet Rule

DefaultClass First Octet Range Idea Subnet Mask------ ------------- ---------- ----------- ------------------A 0xxx xxxx 0~127 N.H.H.H 255.0.0.0B 10xx xxxx 128~191 N.N.H.H 255.255.0.0C 110x xxxx 192~223 N.N.N.H 255.255.255.0D for multicastE for research

18

Class Networks Nodes in each network

A B C

128 256 x 256 x 256

64 x 256 256 x 256

32 x 256 x 256 256

Internet Protocol

19

Subnet

Calss Default Host bits

Maximum borrowing

A 24 22

B 16 14

C 8 6

20

Example 1 172.16.40.4 255.255.255.0

10101100.00010000.00101000.0000010011111111.11111111.11111111.00000000

10101100.00010000.00101000.00000000172 . 16 . 40 . 0

AND

AND

0 0 01 0 00 1 01 1 1

Network Number

172 . 16 . 40 . 4255 . 255 . 255 . 0172 . 16 . 40 . 0

Subnet

AND

21

Example 2 172.16.40.4 255.255.224.0

10101100.00010000.00101000.0000010011111111.11111111.11100000.00000000

10101100.00010000.00100000.00000000172 . 16 . 32 . 0

AND

AND

0 0 01 0 00 1 01 1 1

Network Number

172 . 16 . 00101000 . 4255 . 255 . 11100000 . 0172 . 16 . 00100000 . 0

Subnet

22

Example 3 172.16.0.0 255.255.224.0

11111111.11111111.11100000.00000000 172 . 16 .000xxxxx.xxxxxxxx .001xxxxx.xxxxxxxx .010xxxxx.xxxxxxxx .011xxxxx.xxxxxxxx .100xxxxx.xxxxxxxx .101xxxxx.xxxxxxxx .110xxxxx.xxxxxxxx .111xxxxx.xxxxxxxx

Subnet Mask

Continuous 0 to 1

Subnets 23

Valid subnets 23 -2Total nodes in each subnet 213

Valid nodes in each subnet 213 -2Abbreviation: 172.16.0.0/19

Subnet

23

Example 4 172.16.0.0 / 255.255.255.0

11111111.11111111.11111111.00000000 172 . 16 .00000000.xxxxxxxx .00000001.xxxxxxxx .00000010.xxxxxxxx . … .11111111.xxxxxxxx

Subnet Mask

Continuously borrowing bits from the right

Subnets 28

Total nodes in each subnet 28

172.16.0.0/24

Subnet

24

Network Number: The first node of each networkBroadcast address: The last node of each network

172.16.0.0/20 172.16.32.0172.16.47.255

172.16.0.0/24 172.16.15.0172.16.15.255

172.16.0.0/28 172.16.15.64172.16.15.79

Subnet

25

Subnet

Subnet mask Valid Subnets

Valid nodes

Total valid nodes

IP Saving

255.255.255.192

2 62 124  

255.255.255.224

6 30 180  

255.255.255.240

14 14 196 √

255.255.255.248

30 6 180  

255.255.255.252

62 2 124  

Class C

26

SubnetBest IP Saving

Class Subnet Mask

Total usable nodes

A 255.255.240.0 (212-2) x (212-2)

B 255.255.255.0 (28-2) x (28-2) = 2542

C 255.255.255.240 (24-2) x (24-2) = 196 borrowing bits = left-over bits

27

Subnet

/17 =255.255.128.0

/25 =255.255.255.128

/10 =255.192.0.0

/18 =255.255.192.0

/26 =255.255.255.192

/11 =255.224.0.0

/19 =255.255.224.0

/27 =255.255.255.224

/12 =255.240.0.0

/20 =255.255.240.0

/28 =255.255.255.240

/13 =255.248.0.0

/21 =255.255.248.0

/29 =255.255.255.248

/14 =255.252.0.0

/22 =255.255.252.0

/30 =255.255.255.252

/15 =255.254.0.0

/23 =255.255.254.0

/16 =255.255.0.0

/24 =255.255.255.0

28

IP 10.128.32.64, Find its broadcast IP

/8 10.255.255.255 /17 10.128.127.255 /25 10.128.32.127/10 10.191.255.255 /18 10.128.63.255 /26 10.128.32.127/11 10.159.255.255 /19 10.128.63.255 /27 10.128.32.95/12 10.143.255.255 /20 10.128.47.255 /28 10.128.32.79/13 10.135.255.255 /21 10.128.39.255 /29 10.128.32.71/14 10.131.255.255 /22 10.128.35.255 /30 10.128.32.67/15 10.129.255.255 /23 10.128.33.255/16 10.128.255.255 /24 10.128.32.255

Subnet

29

Find the broadcast address of the following IP：128.1.2.3/29 128.1.2.7 16.65.30.1/20 16.65.31.255128.5.6.7/28 128.5.6.15 16.65.60.1/19 16.65.63.255128.4.5.6/30 128.4.5.7 16.65.140.1/18 16.65.191.255128.3.4.5/26 128.3.4.63 16.65.100.1/17 16.65.127.255128.10.15.20/27 128.10.15.31 16.65.1.1/16 16.65.255.255128.5.160.3/23 128.5.161.255 16.65.0.0/15 16.65.255.255128.6.7.10/25 128.6.7.127 16.65.3.4/14 16.67.255.255128.7.6.4/22 128.7.7.255 16.65.100.200/13 16.71.255.255128.6.27.8/21 128.6.31.255 16.65.128.255/12 16.79.255.255

Subnet

30

IP and Subnet Mask work together to define the neighborhood(network range) of that IP Router uses routing table to make path decision Routing table records the relationship of network number and the router’s interface (port); not the IP to the port Intermediate routers forward packets based on their

destination network number, not the destination IP The final router uses IP to get the MAC of the

destination host, then uses the destination MAC to

deliver the packet (within a frame)

Subnet

31

10.0.0.0 1 x 224 = 224 IP (10.0.0.0~10.255.255)

172.16~31.0.0 16 x 216 = 220 IP (172.16.0.0~172.31.255.255)

192.168.0.0 256 x 28 = 224 IP (192.168.0.0~192.168.255.255)

Private IP

32

When IP and its subnet mask are known, the following can be determined:     The subnet number of this subnet      The broadcast address of this subnet      The range of this subnet      The maximum subnets allowed by this mask      The number of hosts in this subnet    Borrowing bits and total network bits (/number)

http://www.johnscloset.net/cgi/dictionary.pl?Netmask

Summary