Networks 1 st week Understanding the network systems and networks: Network concepts Cable Network devices Network Topologies
Sep 26, 2015
Networks
1st week
Understanding the network systems and networks:
Network concepts Cable Network devices Network Topologies
What Is Networking? Involves connecting computers for the
purpose of sharing information and resources Requires a great deal of technology Offers many possible choices for physical
connections and related software
Networking Fundamentals Consists of two or more computers
connected to each other by wire or cable to transmit data back and forth
Primary motivation arises from a need for individuals to share data quickly and efficiently
Primary Benefits of Networking Permits groups of users to exchange information
routinely and to route data from one individual to another Single consistent master copy of data files
Improves human communication using network services Electronic mail (e-mail)
Enables network device, database & source sharing Fund saving Group working
Network - Why?
Office Representativeat Vietnam
Headquartersat USA Office at
China
Network - Why?
Local and Wide Area Networks LAN
A collection of computers and other networked devices that fit within the scope of a single physical network
Provides the building blocks for internetworks and WANs Distance: ~ km Speed: 100 Mbps
WAN An internetwork that spans distances measured in miles Links together two or more separate LANs
from simple LAN
Hub
Computer
Laptop
Printer
MinicomputerWorkstation
Computer Computer
Server
PC1 PC2 PC3
PC4
PC5
Hub/Switch
Printer
to WAN,
Workstation
Workstation
Workstation
Workstation
Workstation
Workstation
Workstation
Router
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Internet
64 Kbps
Internet
, and Internet !!!
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TCP/IP (Transmission Control Protocol/Internet Protocol)
A Networking Terminologies Clients, peers, and servers Network medium and network messages Network protocols Network software Network services
Clients, Peers, and Servers Server
A computer that shares its resources across the network
Responds to client requests for information by providing the requested information
Client A computer that accesses shared resources Requests information
The Client/Server Relationship
Clients, Peers, and Servers Client/server network
Certain computers take specialized roles and function mostly as servers
Ordinary users machines tend to function mostly as clients
Web, Ftp, Mail servers
Peer-to-peer network Each computer can be a client to other
computers and act as a server as well
The Network Medium Carries Network Messages Network medium
Usually refers to the cable (metallic or fiber-optic) that links computers on a network
Can also describe wireless networking To access any network, computers must attach to
the network medium with a physical interface Network interface card (NIC) Network adapter
Network Protocols Sets of rules for communicating across a
network Examples
TCP/IP (SMTP, POP3, HTTP ) NetBEUI IPX/SPX NWLink
Network Software Issues requests and responses that let
computers take the roles of clients and servers
Network operating system (NOS) Specialized collection of software that gives a
computer the ability to communicate over a network and to take advantage of networking services
Network Services Reside primarily on servers Can include file and print services, file-
sharing, e-mail and other messaging services
Network Models
OSI vs TCP/IP
The Layered Nature of Networked Communications
Cable
Fiber
UTP v RJ-45 jackCoaxial cable
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Unshielded Twisted Pair (UTP) Shielded Twisted Pair (STP)
Data to 100 MbpsC5
Data to 20 Mbps (16 Mbps for Token ring)C4
Data to 10 Mbps (Ethernet)C3
Data to 4 MbpsC2
Voice only (telephone wire)C1
PurposeType
Twisted pair Cable
Cables Coaxial Cable
used normally in cable television or networks. has a better performance than the twisted pair. Bandwidth: ~ 10 Mbps
Thinnet (10Base2) Thicknet (10Base5)
Thinnet connects directly to the network card. Thicknet can be used to connect Thinnet networks. A transceiver is used to connect the 2 cable types.
Coaxial Cable
Cables Fiber optic cable (10BaseF)
These utilized glass or plastic threads to and modulated light waves to carry the signal.
Bandwidth: ~ 2Gbps Distance: ~ km Consumed signal on cable: low
2000Fiber Optic10BaseF500Thick coaxial10Base5185Thin coaxial10Base2
100Unshielded Twisted pair10BaseT
Maximum length (m)Type of cableName
Fiber optic cable
Ethernet Cable Standards Ethernet
10Base-T (100m, Unshielded Twisted Pair = UTP) 10Base-2 (~200m, Coax) 10Base-5 (500m, Coax) 10Base-FL (2000m=2km, Multimode Fiber)
Fast Ethernet 100Base-TX (100m over CAT5 UTP) 100Base-FX (2000m=2km over MM Fiber)
Gigabit Ethernet 1000Base-SX (300m over MM Fiber) 1000Base-LX (550m over MM Fiber, 3000m over
SM Fiber)
Types of network devices NIC Network Interface Card
Types of network devices Repeater:
Layer 1 Physical ~ 100m 2 ports : 1 in, 1 out
Hub Multi-port Repeater
Hubs
Active Hubs Regenerate the signals as they receive them
and send them along Generally have many ports; sometimes called
multiport repeaters Require electrical power to run
Passive Hubs Simply a central connection point Signal passes through the hub without any
amplification or regeneration Require no power
Hybrid Hubs Interconnect different types of cables Maximize a networks efficiency
Intelligent Hub, switch Hub
Types of network devicesBridge:
Forward or receive frame based on MAC address. Used to connect 2 or more networks with the same
protocol. Learning bridge
(auto update)
Switch Switch (Layer 2 - Data Link) : multi-port
Bridge
Router Router (Layer 3 Network)
Router Routers operate at the network layer, connecting two or more
network segments that may different data link layer protocols, but the same network layer protocol.
They can also connect different types of cable. Another important router feature is that they choose the best
route for a packet to follow, hence the name router. This also means that routers need to perform more processing
than bridges or layer 2 switches. Another important difference is that, unlike a bridge, a router only
processes messages that are specifically addressed to it.
Example of Router
Gateway Like routers, gateways also operate at the
network layer, but they are more complex than routers because they provide an interface between more dissimilar networks.
Like routers, gateways only process messages that are specifically addressed to them.
Some gateways operate at the application layer as well.
Example of Gateway
Network Topologies Bus
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http://www22.verizon.com/about/community/learningcenter/articles/images/hsw_HowLanSwtchWk/lan-switch-ring.jpghttp://www.networkthaionline.com/technology/network1/images/network13.gifNetwork Architectures Peer-to-peer Server-based Storage-area Hybrid
Peer-to-peer Networking Any computer can function as either a client
or a server No one computer has any higher priority to
access, or heightened responsibility to provide, shared resources on the network
Every user must act as a system administrator
Typical Peer-to-peer Network
Server-based Networks Users act as clients of dedicated machines
that take the server role
Typical Server-based Network
Storage-area Networks (SANs) Centralized network storage Data transfer occurs over high-speed links for
faster access Appropriate for largest-scale networks
Typical SAN
Hybrid Networks Incorporates both peer-to-peer and server-
based features Sometimes called combination networks
Specialized Servers Application servers Communication servers Domain controllers/directory servers Fax servers File and print servers Mail servers Web servers
Application Servers Supply the server side of client/server
applications, and often the data that goes along with them, to network clients
Communication Servers Provide access to network resources for
users not directly attached to the network (inbound communications)
Permit network users to access external resources not directly attached to the network (outbound communications)
Domain Controllers/Directory Servers Handle the logon services and manage the
collection of computers, users, and so on in a domain
Fax Servers Manage fax traffic for a network
Receive incoming faxes from phone lines and direct them to users across the network
Collect outgoing faxes across the network before sending them over a phone line
Typically use one or more fax modem interfaces
File and Print Servers Most common type of network servers Provide basic networked file storage and
retrieval services and access to networked printers
Let users run applications locally but keep their data files on the server
Mail Servers Manage the flow of e-mail messages for
network users Commonly provide store-and-forward
services
Web Servers The combination of hardware and software
that stores information that is accessible over the Internet via the World Wide Web (WWW)
Selecting the Right Type of Network Budget Number of users Types of applications or network services Requirements for centralized administration
and control
Homework (Group 1)1. Advantages & Disadvantages
a) Peer-to-peer Networkingb) Server-based Networkingc) Storage-area Networking
2. When do choose aa) Peer-to-Peer Networkb) Server-based Network
3. Difference between Repeater, Hub, Bridge, Router and Gateway