Introduction to OSI lower Layer

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Introduction to OSI lower Layer

• Kentaro Hayashi
• Graduate school of Information Science and
  Electrical Engineering
• Department of Advanced Information Technology
• Kyushu University

2
Contents

• OSI Reference Model
• Physical Layer
• Date Link Layer
• Network Layer

3
OSI Reference Model
4
Example of Layer Model

• Postal Mail Service

sender
receiver
Contents Simple, Plain
Representation Language, Meaningful Sentence
Postal format Post Code, Address, Name, Postcard
Transportation method Motor bike, Truck, Train
Some post offices
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OSI Reference Model

• Open Systems Interconnection Reference Model
• In 1977, work on a layered model of network
  architecture,
• which was to become the OSI model, started in
  the
• American National Standards Institute (ANSI)
  working
• group on Distributed Systems (DISY). With the
  DISY
• work and worldwide input, the International
  Organization
• for Standardization(ISO) began to develop its OSI
• networking suite.
• OSI has two major components an abstract model
  of
• networking (the Basic Reference Model, or
  seven-layer
• model) and a set of concrete protocols.
• 
  Wikipedia

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OSI reference model
Application
Presentation
Session
Transport
Network
Data Link
Physical
Layer 7
Network process to application
Layer 6
Data representation and encryption
offer service
Layer 5
Signaling for session
Layer 4
End-to-end connections and reliability
Layer 3
Path determination and logical addressing
offer communication
Layer 2
Physical addressing
Layer 1
Media, signal and binary transmission
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OSI Upper Layer
Application
Presentation
Session
Layer 7
Layer 6
Layer 5
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OSI Lower Layer
Transport
Network
Data Link
Physical
Layer 4
Layer 3
Routing
Layer 2
0101
Data transmission at the node interval
Layer 1
Physical connection
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Transport
Network
Data Link
Physical
Layer 4
Physical Layer
Layer 3
Layer 2
Layer 1
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Physical Layer

• The Physical Layer defines the electrical and
  physical specifications for devices. In
  particular, it defines the relationship between a
  device and a physical medium. This includes the
  layout of pins, voltages, cable specifications,
  Hubs, repeaters, network adapters, and more.
• Wikipedia

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Cable

• Coaxial Cable
• Twisted Pear Cable
• Optical Fiber
• Wireless

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Coaxial cable
1. Inner conductor 2. Insulator surrounding the
Inner conductor 3. Metallic shield and outer
conductor 4. Outer insulating jacket
Characteristic
Few leaks of the electromagnetic wave to the
outside. Able to bend. Able to transmit of a
wide frequency range. Structure is complicated,
and price is high.
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Twisted pair cable
STP (Shielded twisted pair)
UTP (Unshielded twisted pair)
Characteristic
Cheap and Easy to treat. Wire freely.
Affected by the powerful electricity and
electromagnetic .
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Optical fiber
Core Light advances. Cladding Light is
reflected. Buffer Relax shock, absorbent Jacket
Protect.
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Multi mode
Single mode
Strong to bend. Easy to connect. Cheap.
Made of plastic. (Claddingfluorine-based polymer)
Little transmission loss. Made of quartz
glass. ( CoreGe,P , CladdingB,F)
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Wireless Communication
The wiring space is unnecessary. Mobile
communication is possible. Able to build LAN
immediately. Able to communicate outdoors.

• ?Radio?
• Electric wave
• Unnecessary line of sight
• ( license is necessary)
• mobile phone, PHS
• Bluetooth (IEEE 802.15.1)

• ?FSO? Free Space Optics
• Infrared ray (IR)
• or Visible spectrum
• line of sight is required
• license is unnecessary
• PC, remote controller
• IrDA ? UFIR

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Encoding

• NRZ
• (Non-Return to Zero)
• 0 ? Low Level
• 1 ? Hi Level
• ? 1000BASE-X
• NRZI
• (Non-Return to Zero Inversion)
• 0 ? No Change Level
• 1 ? Change Level
• ? FDDI, 100BASE-FX

• Manchester
• 0 ? Hi ?Low
• 1 ? Low?Hi
• ? 10BASE5?2?-T
• MLT-3
• 0 ? No Change Level
• 1 ? Change Level
• (Middle?Hi?Middle?Low?)
• ? 100BASE-TX?CDDI

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Encoding
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Protocol

• RS-232C (Recommended Standard 232C)
• ISDN (Integrated Services Digital Network)
• xDSL (x Digital Subscriber Line)
• - ADSL (Asymmetric DSL)
• IEEE 802.11 (Wireless LAN)
• SDH (Synchronous Digital Hierarchy)
• SONET (Synchronous Optical NETworking)
• Protocol for Ethernet

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IEEE 802.11

• ?one of the wireless LAN related standards

Release Date Frequency band Official speed
IEEE 802.11 1997 2.42.5GHz 2Mbps
IEEE 802.11b October, 1999 2.42.5GHz 11Mbps / 22Mbps
IEEE 802.11a October, 1999 5.155.35GHz5.475.725GHz (Max)54Mbps
IEEE 802.11g June, 2003 2.42.5GHz 54Mbps
IEEE 802.11j -- 4.95.0GHz5.035.091GHz 54Mbps
IEEE 802.11n -- 2.4GHz / 5GHz 100Mbps
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SONET/SDH
SONET SDH Transmission speed
OC-1 - 51.84Mbps
OC-3 STM-1 155.52Mbps
OC-9 - 466.56Mbps
OC-12 STM-4 622.08Mbps
OC-18 - 933.12Mbps
OC-24 - 1244.16Mbps
OC-36 - 1,866.24Mbps
OC-48 STM-16 2,488.32Mbps
OC-192 STM-64 9,953.28Mbps

• ? The international standard of the high speed
  digital communication method with optical fiber

OC Optical Carrier
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Protocol for Ethernet
Transmission speed Maximum length Cable Encoding
10BASE-5 10Mbps 500m Coaxial cable Manchester
10BASE-2 10Mbps 185m Coaxial cable Manchester
10BASE-T 10Mbps 100m Twisted pair cable Manchester
100BASE-TX 100Mbps 100m Twisted pair cable 4B/5B MLT-3
1000BASE-T 1Gbps 100m Twisted pair cable 4D-PAM5(8BIQ4)
100BASE-FX 100Mbps Multi mode412m(half duplex) Optical fiber 4B/5B NRZI
100BASE-FX 100Mbps 2km(full duplex) Optical fiber 4B/5B NRZI
100BASE-FX 100Mbps Single mode20km(full duplex) Optical fiber 4B/5B NRZI
1000BASE-SX 1Gbps Multi mode550m Optical fiber 8B/10B NRZ
1000BASE-LX 1Gbps Multi mode550m Optical fiber 8B/10B NRZ
1000BASE-LX 1Gbps Single mode5km Optical fiber 8B/10B NRZ
1000BASE-ZX 1Gbps 100km Optical fiber 8B/10B NRZ
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Transport
Network
Data Link
Physical
Layer 4
Data Link Layer
Layer 3
Layer 2
Layer 1
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Date Link Layer

• The Date Link Layer provides the functional and
  procedural means to transfer data between network
  entities and to detect and possibly correct
  errors that may occur in the Physical Layer.

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Protocol

• IEEE802.3 (Ethernet)
• FDDI (Fiber distributed data interface)
• ATM (Asynchronous Transfer Mode)
• PPP (Point-to-Point Protocol)
• Token Ring
• ARP (Address Resolution Protocol)
• IEEE802.11(wireless LAN)

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Ethernet

• The protocol that spreads in LAN most today
• American Xerox company, Intel Company and old DEC
  Company devised
• Standardized by IEEE802.3 afterwards
• As for these 2, the forms of the frame are
  different
• CSMA/CD

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Frame Format
Ethernet
Data 461500
Destination MAC address 6
Source MAC address 6
Type 2
FCS 4
Preamble 8octets
IEEE802.3 Ethernet
Data 381492
Destination MAC address 6
Source MAC address 6
SNAP 5
Length 2
LLC 3
FCS 4
Preamble 8
MTU(Maximum Transmission Unit)1518bytes
8 bits 1 bytes 1 octets
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MAC address

• Media Access Control address
• Standardized by IEEE802.3
• The unique address that was allotted to the
  NIC(Network Interface Card)

22 bits
24bits
1 bits
1 bits
48bits
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MAC address

• NIC receives the Frame which destination MAC
  address is same as own one.

A
B
C
D
data
data


?
The destination MAC address is C
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Collision

• Each terminal controls it autonomously to avoid a
  collision of the communication
• In order to avoid collision, Ethernet use CSMA/CD.

A
B
C
D
data
data
data
To D
To C
Collision
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CSMA/CD(Collision Detection)

• Non-persistent CSMA While itself transmits a
  message, It examines that there are only it's
  data in a network
• If a collision happens, It waits in random time
  and retransmits afterwards
• When a collision occurs more than the constant
  number of times, It stops the transmission of a
  message.

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CSMA(Carrier Sense Multiple Access)

• Each terminal controls it autonomously to avoid a
  collision of the communication
• The transmission of a data is performed unless a
  signal is passed to LAN

A
B
C
D
data
data
data
data
Collision
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Switch (Switching Hub)

• Filtering by the MAC address
• It decides the port which It should send

A
B
C
D
data
data
data
?
?
To D
To C
switch
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Transport
Network
Data Link
Physical
Layer 4
Layer 3
Network Layer
Layer 2
Layer 1
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Network Layer

• Network Layer is

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IP

• Protocol developed in U.S. Department of Defense
  (DoD) to bear network layer of TCP/IP model
• IP is a protocol of a connectionless type

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IP

• IP maintains the logic address that is called IP
  address in all machines on the network
• IP address is hierarchized structure and keep
  unique all over the world
• The relay node of IP is called a router.

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IP packet format
Version (4) Header Length (4) Header Length (4) Service Type (8) Packet Length (16) Packet Length (16)
ID (16) ID (16) ID (16) ID (16) Flag (3) Fragment Offset (13)
TTL (8) TTL (8) Protocol (8) Protocol (8) Header Check-Sum (16) Header Check-Sum (16)
Transmission former IP address (32) Transmission former IP address (32) Transmission former IP address (32) Transmission former IP address (32) Transmission former IP address (32) Transmission former IP address (32)
Destination IP address (32) Destination IP address (32) Destination IP address (32) Destination IP address (32) Destination IP address (32) Destination IP address (32)
Option (32 n) Option (32 n) Option (32 n) Option (32 n) Option (32 n) Option (32 n)
Data Data Data Data Data Data
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IP address

• Logic address used by IP protocol
• When you write Internet Protocol address 32 all
  bits are written by one byte by the decimal
  number with the dot separately for four parts
  (octet)
• (?) 11010011 00000111 01011010 01110001 ?
  211.7.90.113

Network address n bits Host address (32 n) bits
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