Transcript network

Review on
Networking Technologies
Linda Wu
(CMPT 471 • 2003-3)
Content
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Network & network categories
Protocol
TCP/IP internet protocol suite
Ethernet technology
References: chapter 1 & 2
Notes-2
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Network & Network Categories
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A network is a group of connected,
communicating devices such as
computers, routers and printers
An internet is two or more networks
that communicate with each other
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Notes-2
Most notable internet: Internet
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Network & Network Categories (cont.)
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Network categories
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Connection-oriented (circuit-switched)
Dedicated connection between 2 points
 Guaranteed network capacity
 Circuit costs are independent of use
e.g. telephone system
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Connectionless (packet-switched)
Data are divided into small pieces (packet)
 Concurrent communication
 Packet is sent only when the network is idle:
delay, bandwidth cannot be guaranteed
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Notes-2
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Network & Network Categories (cont.)
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Packet-Switched Technology
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WAN (wide area network)
Long distance, low speed connection
 A series of packet switches, connected by
long-distance communication lines
 User computer attached to packet switches
 Network is expanded by adding packet switch
& communication line
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LAN (local area network)
High speed connection, short distance
 Computer connects to the network by
Network Interface card (NIC)
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Notes-2
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Protocol
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Protocol is a set of rules that governs
data communication
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A protocol specifies:
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Syntax: the structure or format of data
Semantics: the meaning of each section of bits
Timing: when should data be sent and how fast
can it be sent
The details of message formats
How a source sends a message
How a destination responses when message
arrives
How a computer handles errors or other
abnormal conditions
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TCP/IP Internet Protocol Suite
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Resulted from research funded by US ARPA
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5 layers
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Notes-2
TCP: Transmission Control Protocol
IP: Internet Protocol
Application layer: user applications
Transport layer: end-to-end delivery of data
(TCP, UDP)
Network layer: data transmission across
multiple networks (IP)
Data link layer: organize bits into frames
Physical layer: transmit bits over a medium
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TCP/IP Internet Protocol Suite (cont.)
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ISO/OSI model
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OSI: Open System Interconnect
Introduced by ISO (International Standards
organizations) in late 1970s
TCP/IP protocol suite
OSI model
Dominant network Dominated data communication
architecture currently
before 1990
Notes-2
Protocols
Not protocol; a model for
designing network architecture
Intensively used and
tested in Internet
Never fully implemented
5 layers
7 layers
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TCP/IP Internet Protocol Suite (cont.)
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TCP/IP addressing
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Physical address
defined by WAN or LAN
 Ethernet uses 48-bit physical address
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Internet (IP) address: 32-bit (IPv4)
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Different address formats in different networks
Port address: 16-bit
End objective of internet communication is a
process communicating with another process
 Port address: the label assigned to a process
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Notes-2
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TCP/IP Internet Protocol Suite (cont.)
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Relationship of layers & addresses
Application
layer
Transport
layer
Network
layer
Data link
layer
Physical
layer
Notes-2
Processes
TCP
UDP
Port
address
IP & other protocols
IP
address
Underlying physical
networks
Physical
address
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TCP/IP Internet Protocol Suite (cont.)
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Features
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Network technology independence
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Universal interconnection
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Provide acknowledgement between original
source and final destination
Application protocol standards
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Notes-2
Every computer is assigned a universally unique
address
End-to-end acknowledgement
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Independent of any vendor’s hardware
Include standards for many applications, e.g.,
email, file transfer, remote login
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TCP/IP Internet Services
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Application-level services
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Network-level services
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Notes-2
World Wide Web
Email
File transfer
Remote login
Connectionless packet delivery
Reliable stream transport
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Underlying Physical Technologies
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LAN
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WAN
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Notes-2
Ethernet LAN: most widely used
Token Ring LAN
Wireless LAN
Fiber Distributed Data Interconnect (FDDI) LAN
ARPANET
NSFNET
ANSNET
ATM (asynchronous transfer mode)
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Ethernet Evolution
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10Base5 (Thick Ethernet)
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10Base2 (Thin-wire Ethernet)
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100 Mbps
Gigabit Ethernet
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Notes-2
10 Mbps, connection between a hub and a
computer < 100m
100Base-T (Fast Ethernet)
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10 Mbps, cable < 200m
10Base-T (Twisted pair Ethernet)
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10 Mbps, cable < 500m
1 Gbps
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Thick Ethernet
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Coaxial cable: ½ inch diameter
Host interface card: plug into computer bus
Transceiver: translate analog electrical signals
to / from digital form
AUI (attachment unit interface) cable: control
transceiver operation
transceiver
Ethernet cable
AUI
cable
Host
interface
Notes-2
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Thin-Wire Ethernet
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Coaxial cable: thinner, less expensive, more
flexible (thinnet cable)
Replace costly transceiver with high speed
digital circuit
Direct connection from computer to network
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Computer contains both host interface and circuit that
connects to the cable
Thinnet cable
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Twisted Pair Ethernet
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Notes-2
Reduce cost by replacing coaxial cable
with unshielded copper wire
Connect computer to hub using four pairs
of wires
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Ethernet Properties
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Shared bus
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Support broadcast
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No error checking or tracking
Distributed access control
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All stations receive every transmission
Best-effort delivery
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All stations connect to a single, shared
communication channel
No central authority to grant access
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Ethernet Hardware Address
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Ethernet address: a 48-bit number
Fixed on Ethernet interface hardware
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Address assigning
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Also called: hardware address, physical address,
media access (MAC) address
Ethernet hardware manufactures purchase blocks of
Ethernet addresses, and then,
Assign the addresses in sequence to the Ethernet
interface hardware
No two hardware interfaces have the same
Ethernet address: universally unique
Host interface filters incoming packets based on
their destination addresses
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Ethernet Frame Format
Ethernet Frame: packet that is
transmitted on Ethernet
 Format
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Preamble
Dest. Src.
Addr Addr
Frame
Type
Frame
Data
8
6
2
46~1500 4
6
CRC
Unit: octet (byte)
Preamble: for synchronization
CRC: Cyclic Redundancy Check, for error detection
Notes-2
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