Networking - MENDELU

Networking Lecture Content

• Basic Terms

• Network Categories and Network Topologies

• Network Components

• Wireless Network and Mobile Network

• Network Architecture, OSI Reference Model

• TCP/IP Architecture and Protocols

• IP Addressing and IP Routing

• TCP/IP Transport and Application Layers

• Domain Name System (DNS)

IRC - Lecture 2 - Networking 1


Networking

Objectives of this chapter


• The network infrastructure basics

• The network categories LAN, WAN, WLAN

• The network architecture and network

protocols - essential

• The Reference OSI model principle

• To introduce to the TCP/IP network

architecture which is the fundamental

architecture of Internet

IRC - Lecture 2 - Networking 3 IRC - Lecture 2 - Networking 3

Networking

Basic Terms – Networking – all processes and actions which go on

within the network. Networking is the term that

describes the processes involved in designing,

implementing, upgrading, managing and otherwise

working with networks and network technologies.

– Network – series of points (nodes) interconnected by

communication paths. A network is simply a collection

of computers or other hardware devices that are

connected together, either physically or logically,

using special hardware and software, to allow them to

exchange information and cooperate.


Networking – Communication path (i. e. transmission channel) – physical

and logical environment enabling the data transmission.

Communication path connects two network nodes (the

transmitter and the receiver) that controls the data

transmission through the transmission media (cables or

air).

– Network nodes – devices interconnected within network in

order to be able to communicate with other network nodes.

Network nodes are

• User-end stations (computers) or network peripherals

(printers, scanners …)

• Intermediate devices (repeaters, network switches,

network HUBs, network routers, gateways,….)

Networking

– Network nodes addressing

• HW address (MAC address) is given to a network

adapter when it is manufactured.

– Example: 00-10-5A-44-12-B5

• Logical address (IP address) is configured by user or

administrator or automatically.

– Example: 192.178.100.1

• Domain name is assigned within the Internet Domain

name system (DNS).

– Example: www.mendelu.cz



Networking

Computer network


Networking

• The network can be characterized in terms of spatial

distance or by area of coverage

– Local area network - LAN

– Metropolitan area network - MAN

– Wide area networks - WAN

– Personal area networks - PAN

• The arrangement of the transmission paths („links“)

between network’s nodes is the network topology


IRC - Lecture 2 - Networking

Networking

8

• The network can be characterized in terms of spatial

distance or by area of coverage – Local area network - LAN

– Metropolitan area network - MAN

– Wide area networks - WAN

– In additional: PAN (Personal Area Network)

PAN

https://www.google.cz/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCIedxJ3v7scCFcZvFAod2QEAIQ&url=http://hearinghealthmatters.org/waynesworld/2013/bluetooth-101-part/&psig=AFQjCNEIeZRJHvknOBy_4P9fGUnnEiKNgQ&ust=1442057032287374


Networking

• Two ways of defining network topology

– The physical topology

– The logical topology.

• Physical topology - how devices are physically

connected to the network through the cables that

transmit data

– Bus network topology - every workstation is connected to a

main cable called the bus. Therefore, in effect, each workstation

is directly connected to every other workstation in the network

– Ring network topology - the workstations are connected in a

closed loop configuration.


Networking

– Tree network topology - two or more star networks

connected together. The central devices of the star

networks can be connected to a main bus. Thus, a tree

network is a bus network of star networks.

– The mesh network topology - full mesh or partial mesh.

• Point-to-Point topology

• Fully mesh topology - each workstation is connected directly to

each of the others.

• Partially mesh topology - some workstations are connected to

all the others, and some are connected only to those other nodes

with which they exchange the most data.


Networking

• Logical (or signal) topology describes how devices are

logically connected (i.e. how they communicate with one

another).

Note: In many instances, the logical topology is the same as the

physical topology. But this is not always the case. For example,

some networks are physically connected in a star

configuration, but they operate logically as bus or ring networks


Networking The main topology types:

• Topologies with multiple accesses to transmission media

• Topologies with direct connections

Topologies with multiple accesses to transmission media


Networking


Networking Local Area Network - LAN

• LANs supplie networking capability to a group of computers in relatively short distances to each other such as in a building, in an organization or in an enterprise.

• LANs consist of

– User-end devices (PCs, workstations, servers) and

– Intermediate devices (switches, LAN routers, HUBs …).

• LANs are typically owned, controlled, and managed by a single person or organization.

• LANs use certain specific connectivity technologies, primarily Ethernet.


Networking

The primary LAN technology - Ethernet • Traditional Ethernet supports data transfers at the rate

of 10 Megabits per second (10 Mbps).

• Over time, as the performance needs of LANs have increased, the industry created additional Ethernet specifications

• Fast Ethernet extends traditional Ethernet performance up to 100 Mbps speed

• Gigabit Ethernet extends Fast Ethernet performance up to 1000 Mbps (1 Gbps) speeds.

• 10 Gigabit Ethernet with the speed of 10 Gbps is today the fastest technology for LANs.


The LAN infrastructure

• Typical structure of LAN is the tree topology

• Typical devices of LAN are – Repeaters

– HUBs

– Switches

– Routers

Networking


Networking

• Repeater is a device that receives a digital signal on an

electromagnetic or optical transmission medium and regenerates

the signal along the next segment of the medium

• HUB is a device where data arrives from one or more directions

and is forwarded out in one or more other directions

IRC - Lecture 2 - Networking 18 18

Networking

• Switch is a device that selects the path for sending a unit of data

(packet) to its next destination

• Router is a device that determines the next network point to which

a packet should be forwarded toward its destination. The router is

connected to at least two networks and decides which way to send

each packet using routing table.

Group of network neighbors


Networking

Example of LAN equipment


LAN design examples

1. Home Office and Small Office Network (SOHO LAN)

2. Small to Medium Business (SMB LAN)

3. University Campus or Corporate Campus LAN (CAN)

Networking


Networking

Wide Area Network - WAN • WAN (Wide Area Network) spans a large geographic area (state or

country).

• WANs typically connect multiple smaller networks, such as LANs or MANs.

• The most popular WAN in the world today is the Internet • Many smaller portions of the Internet, such as extranets or

Autonomous Systems are also WANs.

• WAN equipment

– WAN routers

– WAN switches

Note:

Within the Internet, an Autonomous System (AS) is a collection of networks

under the control of one or more network operators (typically ISPs).


Networking


Networking • WANs generally utilize different and much more expensive

networking equipment than do LANs

• Examples of WAN technologies:

– SONET,

– ISDN

– Frame Relay,

– ATM

– Gigabit

– 10Gigabit Ethernet

• WAN technologies offer high-speed networking capabilities,

therefore they are called high-speed transmission technologies

or broad-band transmission technologies

http://www.onsite.co.za/


Networking Wireless Local Area Network – WLAN

(„Wi-Fi“) • Wireless LAN (WLAN) – solution of LAN in a locality

where installation of cables is not possible. Mobile user

can connect to LAN through wireless connection.

• IEEE 802.11 b/g/n standard specifies technologies for

WLAN.

• Topologies for WLAN: – Peer-to-peer (each station communicates with other one directly)

– HUB-based (each station communicates with access point –

HUB unit that controls mutual communication between stations)


IRC - Lecture 2 - Networking

25

Networking

WLAN Architecture • Peer-to-peer/Independent Basic

Service Set (IBSS) - sometimes

referred to as an ad-hoc wireless

network.

• HUB-based with the Access Point that

is usually connected to Distribution

System


Networking

Extended Service Set (ESS)

Enabling roaming between areas of BSS’s trough the distribution system

– LAN backbone


Networking Data services in mobile networks

• Service of mobile operators without Wi-Fi Access Point (Hot Spot)

• Different uplink and downlink transfer speed

• Mobile data transmission technologies

– GPRS (General Packet Radio Services) – packet switching transmission

– High-Speed Circuit-Switched Data (HSCSD)

– EDGE (Enhanced Data GSM Environment) – evolution of GSM (2G)

– UMTS (Universal Mobile Telecommunications Service) – 3G broadband technology

– HSPA - High Speed Packet Access

– LTE – Long Term Evolution 4G

– LTE-A – LTE Advanced

• Internet Access - each mobile phone has one or more IP addresses

allocated

– The direct connection of mobile phone

– The mobile phone is connected to PC by USB or Bluetooth port


Networking


• End user communicates with base station transceiver (BTS)

• BTSs are controlled by base station controllers (BSC)

• BSCs are interconnected to the mobile network backbone with the

mobile switching center (MSC)

• MSC is connected to the other mobile or fixed networks


Networking

Network architecture and protocols • Network interconnects many devices (PC’s, servers, routers,

switches, etc.) using different hardware and software

(operating systems, application programs..).

• The basic requirement is to ensure, that all devices are

able to communicate each to other. (Devices are “open

systems”).

• It requires to create a “common language” for open systems

that is „the protocol“.

• Protocol is a set of definitions and rules used for

communication between two computing end-points over a

communication channel


Networking

• Key elements of protocol – Syntax – the rules for the data format, signal levels …

– Semantics – control information for co-ordination and error handling

– Timing – speed and sequencing

• Paramount concepts in computer communication allowing systems to communicate are:

– Network protocols

– Network protocol architecture - structured set of network protocols


Networking • Fundamental concepts of network protocols

– Messages

– Encapsulation

• Each layer deals with messages. Messages are (generally) limited

to a maximum size.

• For example - Ethernet frames carry only 1500 bytes of data.

Messages larger than 1500 bytes will have to be split into multiple

frames

• Message contains:

– Control part („header“) that contains “instructions” that tell the

remote peer what to do with the message

– Data portion („payload“) that contains arbitrary data, it means

information that users want to share


Principle of encapsulation • The message brings the data (control data and user data) from

one entity to the remote entity.

• The message is passed through the funtional layers within a

system as a packet („Protocol Data Unit“ - PDU)

• Each entity adds its own information like as packet header

Networking


Networking

Principle of Network Architecture • Communication process (communication „tasks“) can be

divided into number of steps(sub-tasks) creating functional layers.

• Each includes a number of functional units (modules or

entities).

• Each functional layer can communicate with a corresponding functional layer on the remote system (by means of the protocol).

• In compliance with appropriate protocol, the message is

originated and is delivered to the remote system.


Networking

Functional layers of computer


• Network architecture is design of network communication capabilities for systems which wish to communicate one another.

• Network architecture consists of a number of protocols („protocol suite“) arranged into defined function layer.

• For each functional entity belonging to given function layer exists one or more protocols.

Example: access to remote mailbox – protocols POP or IMAP belonging to the network architecture TCP/IP

Networking


Network architecture and „open systems“

• Computer or intermediate device (switch/router) implements appropriate network architecture protocols in order to be able of network communication with other computers or intermediate devices on the common network

• Such computer or intermediate device is an open system

• Current network architectures are designed as the layer stack model

Networking


Networking The official standard for „open systems“ became

“Open Systems Interconnect Reference Model”

(OSI Reference Model)

• Publisher: International Organization for Standardization ISO (in

the 1984).

• RM OSI divides communication into 7 functional layers

• The upper layers of the OSI model represent software that implements

network services like file transfer, mail service, connection and remote

session management and so on.

• The lower layers of the OSI model implement more primitive,

hardware-oriented functions like routing, addressing, and flow control

• OSI model remains a practical framework that the most of today's key

network technologies (like Ethernet) and protocols (like IP) fit into.


Networking

The OSI Reference Model

OSI is not a real network architecture,

just a reference for real network architectures.


Networking

OSI Layers Description (1) • Layer 7 (The application layer) - the layer at which

communication partners are identified, quality of service is

identified, user authentication and privacy are considered, and

any constraints on data syntax are identified. (This layer is not

the application itself, although some applications may perform

application layer functions.)

• Layer 6 (The presentation layer) - a layer, usually part of an

operating system, that converts incoming and outgoing data

from one presentation format to another (for example, from a

text stream into a popup window with the newly arrived text).

Sometimes called the syntax layer


Networking

OSI Layers Description (2) • Layer 5 (The session layer) – sets up, coordinates, and

terminates conversations, exchanges, and dialogs between the

applications at each end. It deals with session and connection

coordination

• Layer 4 (The transport layer) - manages the end-to-end control

(for example, determining whether all packets have arrived) and

error checking. It ensures complete data transfer.

• Layer 3 (The network layer) - handles the routing of the data

(sending it in the right direction toward the right destination on

outgoing transmissions and receiving incoming transmissions at

the packet level). The network layer does routing and forwarding.


Networking

OSI Layers Description (3) • Layer 2 (The data link layer) - provides error control and

synchronization for the physical level and does bit-

stuffing for strings of ones.

• Layer 1 (The physical layer) - conveys the bit stream

through the network at the electrical level. It provides the

hardware means of sending and receiving data on

a carrier.


42

Networking

Computers communicating through the OSI model


Networking

TCP/IP Network Architecture • TCP/IP (Transmission Control Protocol/Internet Protocol) is a four-

layered protocol suite.

• TCP/IP is the prime network architecture of the worldwide network

Internet

• TCP/IP network architecture can be used also for communications via

private networks called intranets and in extranets too.

• Each computer is provided with the TCP/IP implementation program just

as every other computer that may send messages to or get information

from another TCP/IP implementing computer

• The TCP/IP protocol implementation is the first requirement for enabling

an access to the Internet from any computer


Networking

Implementation of TCP/IP architecture in the

computer


Networking

Comparison of OSI Reference Model and TCP/IP

architecture (with some of the significant protocols)


Networking

The TCP/IP layers and protocols functionality

description

• Network interface layer provides the access to the

transmission media and the control of the data links

– It is not specified within the TCP/IP specification.

– Its implementation depends on the network technology

used in the particular network (LAN or WAN).

– TCP/IP can be implemented over any type of network

enabling a heterogeneous inter-network to be created.


Networking • Network layer

– IP (Internet Protocol) is the primary protocol of the network or IP

layer in the TCP/IP suite.

• IP protocol supports communication between network devices

• Provides routing facilities based on the implementation of a IP

addressing scheme

• In the addition IP provides fragmentation and reassembly of

datagrams (the IP protocol data units).

– ICMP (Internet Control Message Protocol) protocol, belonging to IP

layer,

• performs a number of tasks, mainly it provides reporting of routing

and datagram delivery failures back to the source device.

• ICMP is an overheads protocol.


Networking

• Transport layer provides data transport services

between two end-user processes. The transport layer

includes two transport protocols

– TCP protocol provides a connection-oriented

transport service. It establishes, controls and

terminates a virtual communication channel

between end-to-end processes

– UDP protocol provides connectionless transport

service with an unreliable (best-efforts) data delivery

between processes on source and destination

computer


Networking

• Application layer of the TCP/IP protocol suite

– It provides the users access to the Internet services

through its protocols.

– There are many different protocols belonging to the

application layer.

– Some of them use the TCP transport service and

others use the UDP transport service


Networking

„Client /Server“model in the TCP/IP applications

• Most of applications are based on the client/server

communication model. The client/server model of

communication is that, in which a computer user (a

client) requests and is provided with a service (such as

sending a Web page) by another computer (a server) in

the network.

• Internet users are familiar with the highest layer

application protocols that use TCP/IP to access the

Internet


Networking Examples of TCP/IP application protocols in Internet

services

– The World Wide Web's Hypertext Transfer Protocol

(HTTP) enabling users access to WWW information

system

– The File Transfer Protocol (FTP) for files transfer from

one file system to another one

– The Telnet Protocol which lets users to logon to remote

computers

– The Simple Mail Transfer Protocol (SMTP) supporting

electronic mail service

– The Internet Message Access Protocol (IMAP) and Post

Office Protocol (POP) enabling users access to

mailboxes from remote machines


Networking

IP addressing • IPv4 addressing scheme implemented in IP protocol allows for

over a billion devices to be uniquely identified and contacted across

an IP network

• IPv4 address is a logical identifier of each Internet node. IP address is

assigned

– statically (manually typewritten configuration file) or

– dynamically through protocol DHCP (Dynamic Host Configuration

Protocol)

• IPv4 address is a 32-bit number that identifies both unique network

number and a host number, which is unique within the network

• Since networks vary in size, there are five different address formats or

classes


Networking

IPv4 address classes


IRC - Lecture 2 - Networking 54 54

Networking

IPv6 addressing schema • The current IP version 4 (IPv4) is progressively replaced with IP version 6

(IPv6). Advantage of IPv6 in comparison with IPv4:

– Bigger address space (more IP addresses is available)

• IPv4 address space – approximately 4 billion addresses

• IPv6 address space – approximately 3.4 x 1038 addresses

– Support of different ways of data transmission (on-request options for

multimedia transmission, for real-time transmission, etc.)

– Data security mechanism embedded (authentication, data encryption,

data integrity checking…)

• Example of IPv6 address:

FE80:0000:0000:0000:0202:B3FF:FE1E:8329 – a full address

FE80::0202:B3FF:FE1E:8329 – a collapsed address

The :: (consecutive colons) notation can be used to represent four successive 16-bit

blocks that contain zeros.


Networking

Domain Name System (DNS) • The number of an IP address can be (and usually is) represented by a

name or series of names called domain name

• Domain name locates an organization or other entity on the Internet.

For example, the domain name akela.mendelu.cz locates an Internet

address for domain "mendelu.cz" and a particular host server named

„akela" at Internet point (i.e. IP address) 195.178.72.100

• DNS namespace - All domain names binding to IP addresses create

hierarchical administrative namespace supporting Internet Domain

name system (DNS)

• A DNS server is a computer registered to join the Domain Name

System. A DNS server runs special-purpose networking software,

features a public IP address, and contains a database of network

names and addresses for other Internet hosts.


Networking

DNS Namespace


Networking

Principle of DNS • Domain names need to be converted to IP addresses as this is

required by lower layer protocols.

• The conversion of domain names to IP addresses is performed by

implementing of DNS protocol.

• DNS protocol implementation

• Since an implementation of the DNS protocol is built into every

network application program, the conversion is fully transparent to

end users


Networking

IP Routing

• Routing is the process of moving information across an

Internet from the source to destination. Along the way, at

least one intermediate device is typically encountered. Such

a device is called a router

• Router is a device, which connects two or more different IP

networks. A router can be an ordinary computer, or it can

be a specific device. If a router joins n different networks, it

has n different network interfaces and forwards data

packets between them.


Networking

• Router takes routing information from a routing table, with one

entry for each identified route.

• The router can create and maintain the routing table dynamically

to accommodate network changes whenever they occur

• Routers exchange routing information using a special routing

protocol for that purpose


Networking

Internet Autonomous Systems • Internet is administratively divided into Autonomous Systems.

• ASs are under maintenance and control of a network operator or

ISP company.

• AS is a collection of networks under a common administration

sharing a common routing strategy.

• Autonomous system number (ASN) is a 16-bit or 32-bit decimal

number that uniquely identifies the autonomous system.

• Internet is interconnection of many autonomous systems - each AS

is connected to the Internet via an exterior router

• Exterior routers communicate one another by exterior routing

protocols (EGP)


• Concept of Autonomous Systems

Networking


Networking Conclusion


• Network is the system of nodes connected together by

links

• Topology is an arrangement of those links

• Within the network the nodes implementing the common

network architecture can communicate each to other

• The Reference model OSI is the base standard for the

network architectures

• The primary network architecture of Internet is TCP/IP,

which consists of o IP (or network) layer

o Transport layer

o Application layer


Networking Answer following questions:

• Explain the terms LAN and WAN.

• Describe the basic types of network topology.

• Describe the devices typical for a LAN infrastructure.

• What is the principle of wireless LANs (WLAN)?

• What is the network architecture?

• What is the purpose of network protocol?

• Which information is contained in the Protocol Data Unit (PDU)?

• What is the purpose of the OSI Reference Model, what is the functionality

of OSI lower layers and upper layers?

• What is the TCP/IP protocol architecture?

• Describe the IP addressing schema.

• What is the purpose of DNS?

• Describe in brief the advantages of the IPv6 in comparison with the IPv4

features.

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Networking - MENDELU