Computer networksComputer networks

Subject code: EC2352

Year: III

Unit: I

Title: Introduction to computer networks

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: I

Title: Introduction to computer networks

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: I

Title: Introduction to computer networks

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: I

Title: Introduction to computer networks

CODED BY: M.KASI RAJAN AP / CSE

Computer Networks

Introduction to Computer Networks

Computer Networks

Computer network connectstwo or more autonomouscomputers.

The computers can begeographically locatedanywhere.

Computer network connectstwo or more autonomouscomputers.

The computers can begeographically locatedanywhere.

Computer network connectstwo or more autonomouscomputers.

The computers can begeographically locatedanywhere.

Computer network connectstwo or more autonomouscomputers.

The computers can begeographically locatedanywhere.

Computer network connectstwo or more autonomouscomputers.

The computers can begeographically locatedanywhere.

LAN, MAN & WAN

Introduction to Computer Networks

LAN, MAN & WAN

Network in small geographical Area (Room, Building or aCampus) is called LAN (Local Area Network)

Network in a City is call MAN (Metropolitan Area Network)

Network spread geographically (Country or across Globe) iscalled WAN (Wide Area Network)

Network in small geographical Area (Room, Building or aCampus) is called LAN (Local Area Network)

Network in a City is call MAN (Metropolitan Area Network)

Network spread geographically (Country or across Globe) iscalled WAN (Wide Area Network)

Network in small geographical Area (Room, Building or aCampus) is called LAN (Local Area Network)

Network in a City is call MAN (Metropolitan Area Network)

Network spread geographically (Country or across Globe) iscalled WAN (Wide Area Network)

Network in small geographical Area (Room, Building or aCampus) is called LAN (Local Area Network)

Network in a City is call MAN (Metropolitan Area Network)

Network spread geographically (Country or across Globe) iscalled WAN (Wide Area Network)

Applications of Networks

Introduction to Computer Networks

Applications of Networks

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Network Topology

Introduction to Computer Networks

Network Topology

The network topologydefines the way in whichcomputers, printers, andother devices areconnected. A networktopology describes thelayout of the wire anddevices as well as thepaths used by datatransmissions.

The network topologydefines the way in whichcomputers, printers, andother devices areconnected. A networktopology describes thelayout of the wire anddevices as well as thepaths used by datatransmissions.

The network topologydefines the way in whichcomputers, printers, andother devices areconnected. A networktopology describes thelayout of the wire anddevices as well as thepaths used by datatransmissions.

The network topologydefines the way in whichcomputers, printers, andother devices areconnected. A networktopology describes thelayout of the wire anddevices as well as thepaths used by datatransmissions.

Bus Topology

Introduction to Computer Networks

Bus Topology

Commonly referred to as alinear bus, all the deviceson a bus topology areconnected by one singlecable.

Commonly referred to as alinear bus, all the deviceson a bus topology areconnected by one singlecable.

Commonly referred to as alinear bus, all the deviceson a bus topology areconnected by one singlecable.

Star & Tree Topology

Introduction to Computer Networks

Star & Tree TopologyThe star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

The star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topologyresembles spokes in a bicyclewheel.

Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames or packets,like bridges, switches, and routers,this topology significantly reducesthe traffic on the wires by sendingpackets only to the wires of thedestination host.

Ring Topology

Introduction to Computer Networks

Ring TopologyA frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

A frame travels around the ring,stopping at each node. If a node wantsto transmit data, it adds the data aswell as the destination address to theframe.

The frame then continues around thering until it finds the destination node,which takes the data out of the frame.

Single ring All the devices on thenetwork share a single cable

Dual ring The dual ring topologyallows data to be sent in bothdirections.

Mesh Topology

Introduction to Computer Networks

Mesh Topology

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

The mesh topologyconnects all devices(nodes) to each other forredundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networkslike those used by banksand financial institutions.

Implementing the meshtopology is expensive anddifficult.

Network Components

Introduction to Computer Networks

Network Components

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

Networking Media

Introduction to Computer Networks

Networking Media

Networking media can bedefined simply as themeans by which signals(data) are sent from onecomputer to another(either by cable or wirelessmeans).

Networking media can bedefined simply as themeans by which signals(data) are sent from onecomputer to another(either by cable or wirelessmeans).

Networking media can bedefined simply as themeans by which signals(data) are sent from onecomputer to another(either by cable or wirelessmeans).

Networking Devices

Introduction to Computer Networks

Networking Devices

HUB, Switches, Routers,Wireless Access Points,Modems etc.

HUB, Switches, Routers,Wireless Access Points,Modems etc.

Computers: Clients and Servers

Introduction to Computer Networks

Computers: Clients and ServersIn a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

In a client/server networkarrangement, networkservices are located in adedicated computer whoseonly function is to respondto the requests of clients.

The server contains thefile, print, application,security, and other servicesin a central computer thatis continuously available torespond to client requests.

Networking Protocol: TCP/IP

Introduction to Computer Networks

Networking Protocol: TCP/IP

Applications

Introduction to Computer Networks

Applications

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

Network ArchitectureNetwork Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

Provides a general, effective, fair, and robust connectivity of computers

Provides a blueprint

Types

OSI ArchitectureInternet Architecture

OSI ARCHITECTUREOSI ARCHITECTURE

Open Systems Interconnection (OSI) model is a reference model developedby ISO (International Organization for Standardization) in 1984

OSI model defines the communications process into Layers

Provides a standards for communication in thenetwork

Primary architectural model for inter-computing and Inter networkingcommunications.

network communication protocols have a structure based on OSI Model

Open Systems Interconnection (OSI) model is a reference model developedby ISO (International Organization for Standardization) in 1984

OSI model defines the communications process into Layers

Provides a standards for communication in thenetwork

Primary architectural model for inter-computing and Inter networkingcommunications.

network communication protocols have a structure based on OSI Model

Open Systems Interconnection (OSI) model is a reference model developedby ISO (International Organization for Standardization) in 1984

OSI model defines the communications process into Layers

Provides a standards for communication in thenetwork

Primary architectural model for inter-computing and Inter networkingcommunications.

network communication protocols have a structure based on OSI Model

Open Systems Interconnection (OSI) model is a reference model developedby ISO (International Organization for Standardization) in 1984

OSI model defines the communications process into Layers

Provides a standards for communication in thenetwork

Primary architectural model for inter-computing and Inter networkingcommunications.

network communication protocols have a structure based on OSI Model

Open Systems Interconnection (OSI) model is a reference model developedby ISO (International Organization for Standardization) in 1984

OSI model defines the communications process into Layers

Provides a standards for communication in thenetwork

Primary architectural model for inter-computing and Inter networkingcommunications.

network communication protocols have a structure based on OSI Model

OSI ArchitectureOSI Architecture

Direct Links: OutlineDirect Links: Outline

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Physical Layer Link technologies Encoding

Link Layer Framing Error Detection Reliable Transmission (ARQ protocols) Medium Access Control:

Existing protocols: Ethernet, Token Rings, Wireless

Link TechnologiesLink Technologies

Cables: Cat 5 twisted pair, 10-100Mbps, 100m Thin-net coax, 10-100Mbps, 200m Thick-net coax, 10-100Mbps, 500m Fiber, 100Mbps-2.4Gbps, 2-40km

Leased Lines: Copper based: T1 (1.544Mbps), T3 (44.736Mbps) Optical fiber: STS-1 (51.84Mbps), STS-N (N*51.84Mbps)

Cables: Cat 5 twisted pair, 10-100Mbps, 100m Thin-net coax, 10-100Mbps, 200m Thick-net coax, 10-100Mbps, 500m Fiber, 100Mbps-2.4Gbps, 2-40km

Leased Lines: Copper based: T1 (1.544Mbps), T3 (44.736Mbps) Optical fiber: STS-1 (51.84Mbps), STS-N (N*51.84Mbps)

Cables: Cat 5 twisted pair, 10-100Mbps, 100m Thin-net coax, 10-100Mbps, 200m Thick-net coax, 10-100Mbps, 500m Fiber, 100Mbps-2.4Gbps, 2-40km

Leased Lines: Copper based: T1 (1.544Mbps), T3 (44.736Mbps) Optical fiber: STS-1 (51.84Mbps), STS-N (N*51.84Mbps)

Cables: Cat 5 twisted pair, 10-100Mbps, 100m Thin-net coax, 10-100Mbps, 200m Thick-net coax, 10-100Mbps, 500m Fiber, 100Mbps-2.4Gbps, 2-40km

Leased Lines: Copper based: T1 (1.544Mbps), T3 (44.736Mbps) Optical fiber: STS-1 (51.84Mbps), STS-N (N*51.84Mbps)

Link TechnologiesLink Technologies

Last-Mile Links: POTS (56Kbps), ISDN (2*64Kbps) xDSL: ADSL (16-640Kbps, 1.554-8.448Mbps), VDSL (12.96Mbps-

55.2Mbps)

CATV: 40Mbps downstream, 20Mbps upstream Wireless Links: Cellular, Satellite, Wireless Local Loop

Last-Mile Links: POTS (56Kbps), ISDN (2*64Kbps) xDSL: ADSL (16-640Kbps, 1.554-8.448Mbps), VDSL (12.96Mbps-

55.2Mbps)

CATV: 40Mbps downstream, 20Mbps upstream Wireless Links: Cellular, Satellite, Wireless Local Loop

Last-Mile Links: POTS (56Kbps), ISDN (2*64Kbps) xDSL: ADSL (16-640Kbps, 1.554-8.448Mbps), VDSL (12.96Mbps-

55.2Mbps)

CATV: 40Mbps downstream, 20Mbps upstream Wireless Links: Cellular, Satellite, Wireless Local Loop

Last-Mile Links: POTS (56Kbps), ISDN (2*64Kbps) xDSL: ADSL (16-640Kbps, 1.554-8.448Mbps), VDSL (12.96Mbps-

55.2Mbps)

CATV: 40Mbps downstream, 20Mbps upstream Wireless Links: Cellular, Satellite, Wireless Local Loop

FRAMING

An efficient data transmission technique

It is a message forwarding system in which data packets, calledframes, are passed from one or many start-points to one

An efficient data transmission technique

It is a message forwarding system in which data packets, calledframes, are passed from one or many start-points to one

An efficient data transmission technique

It is a message forwarding system in which data packets, calledframes, are passed from one or many start-points to one

ApproachesApproaches

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)BISYNC

Binary Synchronous Communication

DDCMP

Digital Data Communication Message Protocol

Bit oriented Protocol(HDLC)Clock based Framing(SONET)

Byte oriented Protocol(PPP)

BISYNC FRAME FORMAT

SYH SYH SOH Header STXBody

ETX CRC

BISYNC FRAME FORMAT

Body

PPP Frame Format

Flag Address Control Protocol Payload Flag

DDCMP Frame Format

SYN SYN Class Count Header Body CRC

Bit Oriented Protocol(HDLC)

Collection of Bits1.HDLC

High-Level Data Link Control

2.Closed Based Framing(SONET)

Synchronous Optical Network

Collection of Bits1.HDLC

High-Level Data Link Control

2.Closed Based Framing(SONET)

Synchronous Optical Network

Collection of Bits1.HDLC

High-Level Data Link Control

2.Closed Based Framing(SONET)

Synchronous Optical Network

Collection of Bits1.HDLC

High-Level Data Link Control

2.Closed Based Framing(SONET)

Synchronous Optical Network

HDLC Frame FormatHDLC Frame Format

Beginning sequence

Header Body CRC Ending sequence

Bit Stufffing

After 5 consecutive 1s insert 0

Next bit is 0 stuffed removedNext bit is 1 end of frame or erorr

Bit Stufffing

After 5 consecutive 1s insert 0

Next bit is 0 stuffed removedNext bit is 1 end of frame or erorr

Bit Stufffing

After 5 consecutive 1s insert 0

Next bit is 0 stuffed removedNext bit is 1 end of frame or erorr

Closed Based Framing(SONET)

STS-1 Frame9 rows of 90 byte each

First 3 byte for overhead rest contains data

Payload bytes scrambled- exclusive OR

Supports Multiplexing

STS-1 Frame9 rows of 90 byte each

First 3 byte for overhead rest contains data

Payload bytes scrambled- exclusive OR

Supports Multiplexing

STS-1 Frame9 rows of 90 byte each

First 3 byte for overhead rest contains data

Payload bytes scrambled- exclusive OR

Supports Multiplexing

STS-1 Frame9 rows of 90 byte each

First 3 byte for overhead rest contains data

Payload bytes scrambled- exclusive OR

Supports Multiplexing

Payloads

9 rows

90 columuns

9 rows

90 columuns

ERROR DETECTIONERROR DETECTION

Detecting Errors In TransmissionElectrical Interference, thermal noise

Approaches

Two Dimensional Parity

Internet Checksum Algorithm

Cyclic Redundancy Check

Detecting Errors In TransmissionElectrical Interference, thermal noise

Approaches

Two Dimensional Parity

Internet Checksum Algorithm

Cyclic Redundancy Check

Detecting Errors In TransmissionElectrical Interference, thermal noise

Approaches

Two Dimensional Parity

Internet Checksum Algorithm

Cyclic Redundancy Check

Detecting Errors In TransmissionElectrical Interference, thermal noise

Approaches

Two Dimensional Parity

Internet Checksum Algorithm

Cyclic Redundancy Check

Detecting Errors In TransmissionElectrical Interference, thermal noise

Approaches

Two Dimensional Parity

Internet Checksum Algorithm

Cyclic Redundancy Check

Two Dimensional Parity

7 bits of data 8 bits including parity 7 bits of data 8 bits including parity

Number of 1s even oddNumber of 1s even odd

0000000 (0) 00000000 100000000

1010001 (3) 11010001 01010001

1101001 (4) 01101001 11101001 1101001 (4) 01101001 11101001

1111111 (7) 11111111 01111111 1111111 (7) 11111111 01111111

Transmission sent using even parity:

A wants to transmit: 1001

A computes parity bit value: 1^0^0^1 = 0

A adds parity bit and sends: 10010

B receives: 10010 B computes parity: 1^0^0^1^0 = 0

B reports correct transmission after observing expected even result.

A wants to transmit: 1001

A computes parity bit value: 1^0^0^1 = 0

A adds parity bit and sends: 10010

B receives: 10010 B computes parity: 1^0^0^1^0 = 0

B reports correct transmission after observing expected even result.

A wants to transmit: 1001

A computes parity bit value: 1^0^0^1 = 0

A adds parity bit and sends: 10010

B receives: 10010 B computes parity: 1^0^0^1^0 = 0

B reports correct transmission after observing expected even result.

A wants to transmit: 1001

A computes parity bit value: 1^0^0^1 = 0

A adds parity bit and sends: 10010

B receives: 10010 B computes parity: 1^0^0^1^0 = 0

B reports correct transmission after observing expected even result.

A wants to transmit: 1001

A computes parity bit value: 1^0^0^1 = 0

A adds parity bit and sends: 10010

B receives: 10010 B computes parity: 1^0^0^1^0 = 0

B reports correct transmission after observing expected even result.

Transmission sent using odd parity:Transmission sent using odd parity:

A wants to transmit: 1001 A computes parity bit value: ~(1^0^0^1) = 1 A adds parity bit and sends: 10011 B receives: 10011 B computes overall parity: 1^0^0^1^1 = 1 B reports correct transmission after observing expected odd result.

A wants to transmit: 1001 A computes parity bit value: ~(1^0^0^1) = 1 A adds parity bit and sends: 10011 B receives: 10011 B computes overall parity: 1^0^0^1^1 = 1 B reports correct transmission after observing expected odd result.

A wants to transmit: 1001 A computes parity bit value: ~(1^0^0^1) = 1 A adds parity bit and sends: 10011 B receives: 10011 B computes overall parity: 1^0^0^1^1 = 1 B reports correct transmission after observing expected odd result.

A wants to transmit: 1001 A computes parity bit value: ~(1^0^0^1) = 1 A adds parity bit and sends: 10011 B receives: 10011 B computes overall parity: 1^0^0^1^1 = 1 B reports correct transmission after observing expected odd result.

Reliable TransmissionReliable Transmission

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Deliver Frames Reliably

Accomplished by Acknowledgements and Timeouts

ARQ-Automatic Repeat Request

Mechanism:

Stop and Wait

Sliding Window

Concurrent Logical Channels

Stop And Wait ARQStop And Wait ARQ

The source station transmits a single frame and then waits for anacknowledgement (ACK).

Data frames cannot be sent until the destination stations replyarrives at the source station.

It discards the frame and sends a negative acknowledgement (NAK)back to the sender

causes the source to retransmit the damaged frame in case of error

The source station transmits a single frame and then waits for anacknowledgement (ACK).

Data frames cannot be sent until the destination stations replyarrives at the source station.

It discards the frame and sends a negative acknowledgement (NAK)back to the sender

causes the source to retransmit the damaged frame in case of error

The source station transmits a single frame and then waits for anacknowledgement (ACK).

Data frames cannot be sent until the destination stations replyarrives at the source station.

It discards the frame and sends a negative acknowledgement (NAK)back to the sender

causes the source to retransmit the damaged frame in case of error

The source station transmits a single frame and then waits for anacknowledgement (ACK).

Data frames cannot be sent until the destination stations replyarrives at the source station.

It discards the frame and sends a negative acknowledgement (NAK)back to the sender

causes the source to retransmit the damaged frame in case of error

The source station transmits a single frame and then waits for anacknowledgement (ACK).

Data frames cannot be sent until the destination stations replyarrives at the source station.

It discards the frame and sends a negative acknowledgement (NAK)back to the sender

causes the source to retransmit the damaged frame in case of error

Acknowledgements & TimeoutsAcknowledgements & Timeouts

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Sender Receiver

Frame

ACKTim

eout

Tim

e

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

ACKTim

eout

Frame

ACKTim

eout

Sender Receiver

Frame

Tim

eout

Frame

ACKTim

eout

(a) (c)

(b) (d)

Stop & wait sequence numbersSender Receiver Sender Receiver

imeo

ut

Sender ReceiverTi

meo

utim

eout

Tim

eout

imeo

ut

Tim

eout

Tim

eout

(c) (d)(c) (d)

(e)

Simple sequence numbers enable the client to discard duplicate copies of the same frame

Stop & wait allows one outstanding frame, requires two distinct sequence numbers

Simple sequence numbers enable the client to discard duplicate copies of the same frame

Stop & wait allows one outstanding frame, requires two distinct sequence numbers

Simple sequence numbers enable the client to discard duplicate copies of the same frame

Stop & wait allows one outstanding frame, requires two distinct sequence numbers

Stop And WaitStop And Wait

Sliding Window Sliding Window

bi-directional data transmission protocol used in the data link layer(OSI model) as well as in TCP

It is used to keep a record of the frame sequences sent

respective acknowledgements received by both the users.

bi-directional data transmission protocol used in the data link layer(OSI model) as well as in TCP

It is used to keep a record of the frame sequences sent

respective acknowledgements received by both the users.

bi-directional data transmission protocol used in the data link layer(OSI model) as well as in TCP

It is used to keep a record of the frame sequences sent

respective acknowledgements received by both the users.

bi-directional data transmission protocol used in the data link layer(OSI model) as well as in TCP

It is used to keep a record of the frame sequences sent

respective acknowledgements received by both the users.

Sliding Window: SenderSliding Window: Sender

Assign sequence number to each frame (SeqNum) Maintain three state variables:

send window size (SWS) last acknowledgment received (LAR) last frame sent (LFS)

Maintain invariant: LFS - LAR

Sequence Number SpaceSequence Number Space

SeqNum field is finite; sequence numbers wrap around Sequence number space must be larger then number of outstanding frames SWS

Sliding Window: ReceiverSliding Window: Receiver

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

RWS

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

RWS

LFR LFA

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

Maintain three state variables receive window size (RWS) largest frame acceptable (LFA) last frame received (LFR)

Maintain invariant: LFA - LFR LFA discarded

Send cumulative ACKs send ACK for largest frame such that all frames less than this have been received

EhernetEhernet

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

local-area network (LAN) covered by the IEEE 802.3.

two modes of operation: half-duplex full-duplex modes. .

Three basic elements :

1. the physical medium used to carry Ethernet signals betweencomputers,

2. a set of medium access control rules embedded in eachEthernet interface that allow multiple computers to fairlyarbitrate access to the shared Ethernet channel,

3. an Ethernet frame that consists of a standardized set of bitsused to carry data over the system

Three basic elements :

1. the physical medium used to carry Ethernet signals betweencomputers,

2. a set of medium access control rules embedded in eachEthernet interface that allow multiple computers to fairlyarbitrate access to the shared Ethernet channel,

3. an Ethernet frame that consists of a standardized set of bitsused to carry data over the system

Three basic elements :

1. the physical medium used to carry Ethernet signals betweencomputers,

2. a set of medium access control rules embedded in eachEthernet interface that allow multiple computers to fairlyarbitrate access to the shared Ethernet channel,

3. an Ethernet frame that consists of a standardized set of bitsused to carry data over the system

Three basic elements :

1. the physical medium used to carry Ethernet signals betweencomputers,

2. a set of medium access control rules embedded in eachEthernet interface that allow multiple computers to fairlyarbitrate access to the shared Ethernet channel,

3. an Ethernet frame that consists of a standardized set of bitsused to carry data over the system

Three basic elements :

1. the physical medium used to carry Ethernet signals betweencomputers,

2. a set of medium access control rules embedded in eachEthernet interface that allow multiple computers to fairlyarbitrate access to the shared Ethernet channel,

3. an Ethernet frame that consists of a standardized set of bitsused to carry data over the system

IEEE 802.5 FormatIEEE 802.5 Format

Frame Format IEEE 802.5Frame Format IEEE 802.5

IEEE 802.3 MAC Data Frame Format IEEE 802.3 MAC Data Frame Format

WirelessWireless

The process by which the radio waves are propagated through airand transmits data

Wireless technologies are differentiated by :

Protocol Connection typePoint-to-Point (P2P) SpectrumLicensed or unlicensed

The process by which the radio waves are propagated through airand transmits data

Wireless technologies are differentiated by :

Protocol Connection typePoint-to-Point (P2P) SpectrumLicensed or unlicensed

The process by which the radio waves are propagated through airand transmits data

Wireless technologies are differentiated by :

Protocol Connection typePoint-to-Point (P2P) SpectrumLicensed or unlicensed

The process by which the radio waves are propagated through airand transmits data

Wireless technologies are differentiated by :

Protocol Connection typePoint-to-Point (P2P) SpectrumLicensed or unlicensed

The process by which the radio waves are propagated through airand transmits data

Wireless technologies are differentiated by :

Protocol Connection typePoint-to-Point (P2P) SpectrumLicensed or unlicensed

TypesTypes

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

Infrared Wireless Transmission

Tranmission of data signals using infrared-light waves

Microwave Radio

sends data over long distances (regions, states, countries) at up to 2 megabits per second (AM/FM Radio)

Communications Satellites microwave relay stations in orbit around the earth.

UNIT III Packet SwitchingUNIT III Packet Switching

Is a network communications method Groups all transmitted data, irrespective of content, type, or structure

into suitably-sized blocks, called packets.

Optimize utilization of available link capacity Increase the robustness of communication. When traversing network adapters, switches and other network nodes packets are buffered and queued, resulting in variable delay and

throughput, depending on the traffic

Is a network communications method Groups all transmitted data, irrespective of content, type, or structure

into suitably-sized blocks, called packets.

Optimize utilization of available link capacity Increase the robustness of communication. When traversing network adapters, switches and other network nodes packets are buffered and queued, resulting in variable delay and

throughput, depending on the traffic

Is a network communications method Groups all transmitted data, irrespective of content, type, or structure

into suitably-sized blocks, called packets.

Optimize utilization of available link capacity Increase the robustness of communication. When traversing network adapters, switches and other network nodes packets are buffered and queued, resulting in variable delay and

throughput, depending on the traffic

Is a network communications method Groups all transmitted data, irrespective of content, type, or structure

into suitably-sized blocks, called packets.

Optimize utilization of available link capacity Increase the robustness of communication. When traversing network adapters, switches and other network nodes packets are buffered and queued, resulting in variable delay and

throughput, depending on the traffic

TypesTypes

Connectionless each packet is labeled with a connection ID rather than

an address.

Example:Datagram packet switching

connection-oriented each packet is labeled with a destination address Example:X.25 vs. Frame Relay

Connectionless each packet is labeled with a connection ID rather than

an address.

Example:Datagram packet switching

connection-oriented each packet is labeled with a destination address Example:X.25 vs. Frame Relay

Connectionless each packet is labeled with a connection ID rather than

an address.

Example:Datagram packet switching

connection-oriented each packet is labeled with a destination address Example:X.25 vs. Frame Relay

Connectionless each packet is labeled with a connection ID rather than

an address.

Example:Datagram packet switching

connection-oriented each packet is labeled with a destination address Example:X.25 vs. Frame Relay

Connectionless each packet is labeled with a connection ID rather than

an address.

Example:Datagram packet switching

connection-oriented each packet is labeled with a destination address Example:X.25 vs. Frame Relay

Star TopologyStar Topology

Source RoutingSource Routing

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

0

13

2

0

1 3

2

0

13

2

0

13

23 0 1 3 01

30 1

Switch 3

Host B

Switch 2

Host A

Switch 1

Virtual Circuit SwitchingVirtual Circuit Switching Explicit connection setup (and tear-down) phase Subsequence packets follow same circuit Sometimes called connection-oriented model

Explicit connection setup (and tear-down) phase Subsequence packets follow same circuit Sometimes called connection-oriented model

132

013

2Switch 2

Switch 1

0

1325 11

Host A

Analogy: phone call

Each switch maintains a VC table

01 3

7

Switch 3

Host A

Analogy: phone call

Each switch maintains a VC table

1 3

24 Host B

Analogy: phone call

Each switch maintains a VC table

Datagram SwitchingDatagram Switching

No connection setup phase Each packet forwarded independently Sometimes called connectionless model

No connection setup phase Each packet forwarded independently Sometimes called connectionless model

Host D

No connection setup phase Each packet forwarded independently Sometimes called connectionless model

2

0

13Switch 2

Switch 1

Host D

Host EHost F Analogy: postal

system

Each switch maintains a forwarding (routing) table

0

13

22

Switch 2

Host A

Host C

Analogy: postal system

Each switch maintains a forwarding (routing) table

0 Switch 3Host B

Host A

Host G

Analogy: postal system

Each switch maintains a forwarding (routing) table

0

1 3

2

Switch 3Host BHost G

Host HHost H

Virtual Circuit ModelVirtual Circuit Model

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Typically wait full RTT for connection setup before sending first data packet.

While the connection request contains the full address for destination

each data packet contains only a small identifier, making the per-packet header overhead small.

If a switch or a link in a connection fails, the connection is broken and a new one needs to be established.

Connection setup provides an opportunity to reserve resources.

Datagram ModelDatagram Model

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

There is no round trip delay waiting for connection setup; ahost can send data as soon as it is ready.

Source host has no way of knowing if the network is capable ofdelivering a packet or if the destination host is even up.

Since packets are treated independently, it is possible to routearound link and node failures.

Since every packet must carry the full address of thedestination, the overhead per packet is higher than for theconnection-oriented model.

Bridges and Extended LANsBridges and Extended LANs

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids

A B C

Port 1

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids

Bridge

X Y Z

Port 1

Port 2

LANs have physical limitations (e.g., 2500m) Connect two or more LANs with a bridge

accept and forward strategy level 2 connection (does not add packet header)

Ethernet Switch = Bridge on Steroids X Y Z

Spanning Tree Algorithm Spanning Tree Algorithm

Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

A Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

B3

A

C

DB2

B5

B

B7 K

Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

E

B2 B7 K

F

H

B1

G

Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

H

B4

J

B6

G

I

Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

Problem: loops

Bridges run a distributed spanning tree algorithm select which bridges actively forward developed by Radia Perlman now IEEE 802.1 specification

Algorithm DetailsAlgorithm Details

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Algorithm DetailsAlgorithm Details

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Bridges exchange configuration messages id for bridge sending the message id for what the sending bridge believes to be root bridge distance (hops) from sending bridge to root bridge

Each bridge records current best configuration message for each port

Initially, each bridge believes it is the root

Thank UCODED BY: M.KASI RAJAN AP / CSE

Thank UCODED BY: M.KASI RAJAN AP / CSE

Thank UCODED BY: M.KASI RAJAN AP / CSE

Computer networksComputer networks

Subject code: EC2352

Year: III

Unit: II

Title: Introduction to network layers

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: II

Title: Introduction to network layers

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: II

Title: Introduction to network layers

CODED BY: M.KASI RAJAN AP / CSE

Subject code: EC2352

Year: III

Unit: II

Title: Introduction to network layers

CODED BY: M.KASI RAJAN AP / CSE

InternetworkingInternetworking

An internetwork is a collection of individual networks, connected byintermediate networking devices, that functions as a single largenetwork.

different kinds of network technologies that can be interconnectedby routers and other networking devices to create an internetwork

An internetwork is a collection of individual networks, connected byintermediate networking devices, that functions as a single largenetwork.

different kinds of network technologies that can be interconnectedby routers and other networking devices to create an internetwork

An internetwork is a collection of individual networks, connected byintermediate networking devices, that functions as a single largenetwork.

different kinds of network technologies that can be interconnectedby routers and other networking devices to create an internetwork

An internetwork is a collection of individual networks, connected byintermediate networking devices, that functions as a single largenetwork.

different kinds of network technologies that can be interconnectedby routers and other networking devices to create an internetwork

TypesTypes

Local-area networks (LANs)enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity.

technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others.

Local-area networks (LANs)enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity.

technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others.

Local-area networks (LANs)enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity.

technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others.

Local-area networks (LANs)enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity.

technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others.

Local-area networks (LANs)enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers.

Wide-area networks (WANs) interconnect LANs with geographically dispersed users to create connectivity.

technologies used for connecting LANs include T1, T3, ATM, ISDN, ADSL, Frame Relay, radio links, and others.

ETHETH

IPV4 Packet HeaderIPV4 Packet Header

Version HLen TOS LengthVersion HLen TOS Length

Ident Flags OffsetFlags Offset

TTL Protocol Checksum

SourceAddr

Destination AddrDestination Addr

Options(variable) Pad(variable)

DataData

Datagram DeliveryDatagram Delivery

Packet FormatPacket Format

IPV4 Packet headerIPV4 Packet header

Fragmentation and ReassemblyFragmentation and Reassembly

Fragmentation and ReassemblyFragmentation and Reassembly

Fragmentation and ReassemblyFragmentation and Reassembly

(RARP)Reverse Address Resolution Protocol

(RARP)Reverse Address Resolution Protocol

(RARP) is a Link layer networking protocol RARP is described in internet EngineeringTask ForceETF) publication

RFC 903

It has been rendered obsolete by the Bootstrap Protocol (BOOTP) and the modern Dynamic Host Configuration Protocol(DHCP)

BOOTP configuration server assigns an IP address to each client from a pool of addresses.

BOOTP uses the User Datagram Protocol (UDP)

(RARP) is a Link layer networking protocol RARP is described in internet EngineeringTask ForceETF) publication

RFC 903

It has been rendered obsolete by the Bootstrap Protocol (BOOTP) and the modern Dynamic Host Configuration Protocol(DHCP)

BOOTP configuration server assigns an IP address to each client from a pool of addresses.

BOOTP uses the User Datagram Protocol (UDP)

(RARP) is a Link layer networking protocol RARP is described in internet EngineeringTask ForceETF) publication

RFC 903

It has been rendered obsolete by the Bootstrap Protocol (BOOTP) and the modern Dynamic Host Configuration Protocol(DHCP)

BOOTP configuration server assigns an IP address to each client from a pool of addresses.

BOOTP uses the User Datagram Protocol (UDP)

(RARP) is a Link layer networking protocol RARP is described in internet EngineeringTask ForceETF) publication

RFC 903

It has been rendered obsolete by the Bootstrap Protocol (BOOTP) and the modern Dynamic Host Configuration Protocol(DHCP)

BOOTP configuration server assigns an IP address to each client from a pool of addresses.

BOOTP uses the User Datagram Protocol (UDP)

(RARP) is a Link layer networking protocol RARP is described in internet EngineeringTask ForceETF) publication

RFC 903

It has been rendered obsolete by the Bootstrap Protocol (BOOTP) and the modern Dynamic Host Configuration Protocol(DHCP)

BOOTP configuration server assigns an IP address to each client from a pool of addresses.

BOOTP uses the User Datagram Protocol (UDP)

Router

Routing

RouterA router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

A router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

A router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

A router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

A router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

A router is a device that determines the next network pointto which a packet should be forwarded toward itsdestination

Allow different networks to communicate with each other

A router creates and maintain a table of the availableroutes and their conditions and uses this information todetermine the best route for a given packet.

A packet will travel through a number of network pointswith routers before arriving at its destination.

There can be multiple routes defined. The route with alower weight/metric will be tried first.

Routing

Routing

Routing

Routing Protocols

Routing

Routing ProtocolsStatic Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

Static Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

Static Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

Static Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

Static Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

Static Routing

Dynamic Routing

IGP (Interior Gateway Protocol): Route data within an Autonomous System

RIP (Routing Information Protocol)

RIP-2 (RIP Version 2)

OSPF (Open Shortest Path First)

IGRP (Interior Gateway Routing Protocol)

EIGRP (Enhanced Interior Gateway Routing Protocol)

IS-IS

EGP (Exterior Gateway Protocol): Route data between AutonomousSystems

BGP (Border Gateway Protocol)

The Routing AlgorithmThe Routing AlgorithmThe Routing AlgorithmThe Routing Algorithm

u the shortest path tree is contained in the routing table

u Calculations are based on the Bellman-Ford algorithm

u the shortest path tree is contained in the routing table

u Calculations are based on the Bellman-Ford algorithm

u the shortest path tree is contained in the routing table

u Calculations are based on the Bellman-Ford algorithm

u the shortest path tree is contained in the routing table

u Calculations are based on the Bellman-Ford algorithm

Iskra Djonova-Popova

The Centralized Version of the The Centralized Version of the AlgorithmAlgorithm

The Centralized Version of the The Centralized Version of the AlgorithmAlgorithm

21 21

A B C2

4

1 A B C2

3 4

1

D E

3 4 56 D E

3 4

Cycle Node B C D E

Initial (., ) (., ) (., ) (., )

1 (1, 1) (2, 2) (3, 1) (4, 2)

D E

Cycle Node B C D E

Initial (., ) (., ) (., ) (., )

1 (1, 1) (2, 2) (3, 1) (4, 2)

Iskra Djonova-Popova

The Distributed VersionThe Distributed Version

A B C1 2

Routing table for AA B C

3 4

From A to Link CostB 1 1C 1 2D 3 1E 1 2

D E

3 4

5

6

From A to Link CostB 1 1C 1 2D 3 1E 1 2

D E6

Example of simple network with 5 nodes (routers) and 6 links (interfaces)The cost of all links is assumed to be 1

Example of simple network with 5 nodes (routers) and 6 links (interfaces)The cost of all links is assumed to be 1

Iskra Djonova-Popova

AdvantagesAdvantages

simple to implement

low requirement in processing and memory at the nodes

suitable for small networks

simple to implement

low requirement in processing and memory at the nodes

suitable for small networks

simple to implement

low requirement in processing and memory at the nodes

suitable for small networks

simple to implement

low requirement in processing and memory at the nodes

suitable for small networks

Iskra Djonova-Popova

DisadvantagesDisadvantages

Slow convergenceBouncing effectCounting to infinity problem

Slow convergenceBouncing effectCounting to infinity problem

Slow convergenceBouncing effectCounting to infinity problem

Slow convergenceBouncing effectCounting to infinity problem

Slow convergenceBouncing effectCounting to infinity problem

Iskra Djonova-Popova

Slow ConvergenceSlow Convergence

A B C2

XXXA B C

3 4

XXX

link 1 breaks

D E

3 4

5

6

link 1 breaks

D E

When a link breaks the routers are supposed to reestablish the routing tables

Iskra Djonova-Popova

The Bouncing EffectThe Bouncing Effect

A B CXXX

1A B C

3 4

XXX

D E

3 4

5

6

link 2 breaks and A sends its routing table to B before B sends it to A

D E

link 2 breaks and A sends its routing table to B before B sends it to A

Iskra Djonova-Popova

Counting to Infinity ProblemsCounting to Infinity Problems

A B C2

XXX

3

A B C

4

XXX

Links 1 and 6break.D E

3 4

5

XXX

Links 1 and 6break.D EXXXLinks 1 and 6break.

A sends its old routing table before D sends the new routing tableA sends its old routing table before D sends the new routing table

Iskra Djonova-Popova

A sends its old routing table before D sends the new routing table

SubnetsSubnets

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

Each organization assigns IP addresses to specific computers on its networks

IP addresses are assigned so that all computers on the same LAN have similar addresses

Each of these lans is known as a TCP/IP subnet Any portion of the IP address can be

designated as a subnet using a subnet mask*

* Subnet masks tell computers what part of an IP address is to be used to determine whether a destination is on the same or a different subnet

* Subnet masks tell computers what part of an IP address is to be used to determine whether a destination is on the same or a different subnet

Subnet AddressingSubnet Addressing

Figure 5-6

Subnet AddressingSubnet Addressing

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

Subnet AddressingSubnet Addressing

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

Providing AddressesProviding Addresses

Providing addresses to networked computers

Static addressing Dynamic addressing

Pr