Transcript Network - Blog Universitas Udayana

Network
Minggu ke – 9
Magister Teknik Elektro
Universitas Udayana
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• What is a Network?
– Allows Computers to Communicate
– Share Files, Printers and Other Peripherals
– Connect to a Centralized Server
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• Network Communications and Protocols
– Protocol - The definition of a language that allows
computers and networks to communicate
• OSI Model
– Breaks network protocols down into seven different
layers.
• Computer Protocols
– Languages Computers use to communicate across
networks
• Network Protocols
– Languages Networks use to communicate
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Network Communications and Protocols
Computer Protocols
• NetBEUI (NetBIOS Extended User Interface)
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Microsoft Windows
File and Printer Sharing
Easiest to Setup
Works Best on Small Networks
– Less Than 25 Computers
• Large Networks Require WINS Server
• Alternative is NetBIOS over TCP/IP
• IPX/SPX and NWLink (NetWare)
• Allows Windows computers to communicate with Novell
based networks
• Available as of Windows 95 and NT 4.0
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• TCP/IP
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Most widely used protocol today
Protocol used across the Internet hence IP
Packet based
IP Based Networks
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IP Addresses
Subnet Masks
Gateway
DHCP (Dynamic Host Configuration Protocol )Server
DNS Server
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• Public IP Addresses
– Given out in “Blocks”
– Computers with Public IP addresses can be directly
accessed from the Internet
– Poses Potential Security Risk
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• Private IP Addresses
– Can not directly
connect to the Internet
– Translated to public IP
address prior to
sending data on the
Internet
– Free for anyone to use
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• TCP/IP : IP
Addresses
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Dynamic vs. Static
Subnet Mask
Gateway
DNS Server
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Subnetting
A Network with two levels of hierarchy (not
subnetted)
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A Network with three levels of hierarchy
(subnetted)
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ARP (Address Resolution Protocol)
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• Cross Platform Communications
– Linux / Unix / Mac OS X
• Samba – Allows these operating systems to use
the NetBIOS Protocol to communicate with
Windows operating systems
– Windows
• Services for Unix (SFU) – Allows Windows
operating systems to use the NFS protocol to
communicate with Linux / Unix operating systems
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• OSI Model
– Breaks network protocols down into seven different
layers.
• Protocol functions
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Segmentation and reassembly
Encapsulation
 Addressing
Connection control
 Multiplexing
Ordered delivery
 Transmission services
Flow control
Error control
synchronization
• Computer Protocols
– Languages Computers use to communicate across
networks
• Network Protocols
– Languages Networks use to communicate
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Layer
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Application
Usersoriented
Presentation
Users of
transport
service
Session
End-to-end
connection
oriented
Transport
Network
Data Link
Point-topoint link
oriented
Network
service
Physical
Perspective on the OSI architecture
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O
P
E
R
A
T
I
N
G
s
y
s
t
e
m
Applications
TCP
IP
Network
Access
protocol
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Network Protocol
• Token Ring
– Backbone for large ring
topologies
– Uses special packet called a
Token
– Computer holding token allowed
to communicate on network
• Ethernet
– • Designed for LAN technologies
- Bus topology; Fast Ethernet: 100
Mbps; Gigabits Ethernet: 1000
Mbps
– • Listens to network before
transmission
– • Uses random wait times to
resolve collisions
– • Not limited to Ring Topology
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• Ethernet implementations
10Base5: Thick Ethernet or Thicknet
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10Base2: Thin Ethernet or Cheapernet
It uses bus topology with an internal transceiver or p2p connection via an external transceiver.
If the station uses an internal transceiver, there is no need for an AUI cable
If the station lacks a transceiver, then an external transceiver can be used in conjunction with
the AUI
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Segments
Max. 5 segments, each segment max 185 m.
Only 3 segments for connecting stations to medium; 2 segments for
remote repeaters
The max.no. stations 96, 32 stations/segment
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Medium & Connectors
Descriptions
Thin coaxial cable
Spec. in table
BNC-type coaxial
connectors
For the end of each segment
BNC-type barrel connector To connect 2 sections of a segment together
BNC-type terminators
50-ohm terminator
BNC-type tee connectors
To connect the medium to the external transceiver
or to the NIC
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10Base-T: Twisted-Pair Ethernet
Physically is star topology, logically is bus topology
The stations are connected to a hub with either an internal or external transceiver
Internal transceiver: no need AUI cable
External transceiver: AUI cable for connecting the transceiver – interface
Medium & connectors: twisted-pair cable and RJ-45 connectors
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10Base-FL: Fiber Link Ethernet
Star topology, External transceiver: fiber-optic MAU
AUI Cable: to connect the station – external transceiver
Spec. 10Base-FL:
Duplexity: Full-duplex
Physical topology: star
Medium: Fiber 62.5/125 m
Max. length: 2000 m
Medium and connectors
Descriptions
Medium &
Connectors
Fiber optic cable
Graded index multimode with a 62.5 m core and 125
m cladding
ST connector
Type for fiber-optic medium
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VLAN (Virtual Local Area Network)
A subnetwork or a segment of a local area network configured by software, not by physical wiring
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VPN (Virtual Private Network)
A network that is private, but virtual
It is private because it guarantees privacy inside the organization.
It is virtual because it does not use real private WANs; the network is physically public,
but virtually private
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Network Fast Ethernet
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Gigabit Ethernet Architecture Standard
Media Access Control (MAC)
full duplex and/or half duplex
Gigabit Media Independent Interface (GMII)
(optional)
1000 Base – X PHY
8B/10B auto-negotiation
1000 Base-LX
1000 Base T
PCS
1000 Base-SX 1000 Base-CX
Fiber optic
transceiver
Fiber optic
transceiver
Copper
transceiver
Single Mode or
Multimode Fiber
Multimode
Fiber
Shieled
Copper Cable
1000 Base T
PMA
transceiver
Unshielded twisted pair
IEEE 802.3ab
IEEE 802.3z
Source - IEEE
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Gigabit Ethernet Technology
Figure 4-23.Gigabit Ethernet cabling.
1000 BASE SX
fiber - short wavelength
1000 BASE LX
fiber - long wavelength
1000 BASE CX
copper - shielded twisted pair
1000 BASE T
copper - unshielded twisted pair
* Based on Fiber Channel physical signaling technology.
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Network Hardware
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Network Hardware
• NIC – Network Interface Card
• Cabling
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Cat 5
Cat 5e
Cat 6
Fiber Optic
• Hub or Repeater
– Repeats information out to all ports
– Creates unnecessary network traffic
– Least sophisticated of all network equipment
• Switch
– Analyzes packets and routes directly to destination port
– More efficient than hub
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Network Hardware
• Router
– More sophisticated than Switch
– Knows what type of traffic
– Can be used as first line of defense when securing a network
• Firewall
– Not only knows type of traffic, but analyzes traffic for potential
vulnerabilities.
– Rule based analysis
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• WAP – Wireless Access Point
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Slower than traditional wired networks
Great for open spaces
Quickly reduces distances inside buildings
Can reach over a few miles with proper equipment
Less expensive than wired counterparts
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Internet Connection
• Types of Connections
– Dial Up
• Slow
• Maximum Throughput 50Kbps
– Satellite
• • Available even in rural areas
• • Long response times (Latency)
• • Maximum Throughput 50Kbps up and 400Kbps down
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– DSL / Cable
• • Increase speeds as needed
• • Requires Phone Company or Cable Company
Support
– T1
• • Maximum throughput 1,500 Kbps
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xDSL
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Network Security
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Firewalls
Router
VPN – Virtual Private Networking
Wireless - WiFi
– WEP – Wireless Encryption Protocol
– WPA – WiFi Protected Access
– Ethernet Address Lockdown
• Physical Security
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