ali.dmohammadi@ gmail.com orientation ali.dmohammadi@ gmail.com orientation 1-1 orientation computer...
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ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-11
Orientation
Computer NetworksComputer Networks
Shahrood University of TechnologyShahrood University of TechnologyDepartment of Computer Engineering & ITDepartment of Computer Engineering & IT
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-22
Chapter 1: OrientationChapter 1: Orientation
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-33
Distributed Software Application (will be discussed): WEB, email, 3-tier appl., … Database Directory
Resource Sharing File, Software, Data, … (Network File System, File
Transfer, …) CPU, Memory, Peripherals, …
Communication Email, Chat, TV, Radio, Video Conference,
Telephone, . Virtual Terminal (Remote Login)
Why Networking !Why Networking !
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-44
Platform (OS + Hardware)
Application Program Interface (API)
Application Software
Platform (OS + Hardware)
Application Program Interface (API)
Application process
Application process
Application process
Application process
Inter-process Communication
Platform Services Graphics Data Interchange Data Management User Interface Software Engineering Communication
Services
Application AgentApplication Agent
Application SoftwareApplication Software
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-55
Distributed Applications or Network Application: Distributed Applications or Network Application: Client/ServerClient/Server
Application Software (Client Part)
Application Software (Client Part)
Networking Software & HardwareNetworking Software & Hardware
Application Software (Server Part)
Application Software (Server Part)
Client (user) AgentClient (user) Agent Server AgentServer Agent
CommunicationCommunicationNetworkNetwork
Client Agents Examples: Internet Explorer + http,
Opera + http MS’s Outlook + SMTP,
Netscape’s Messenger + SMTP, Eudora + SMTP
… next slide
Application Program Interface (API) Application Program Interface (API)Syste
mA
pplica
tion
Platform (OS + Hardware)Platform (OS + Hardware)
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-66
Application process
Application process
Client/Server ApplicationsClient/Server Applications
Application Program Interface (API) Application Program Interface (API)
Networking Software & HardwareNetworking Software & Hardware
CommunicationCommunicationNetworkNetwork
Platform (OS + Hardware) Platform (OS + Hardware)
Application Process(Client Side)
Application Process(Client Side)
Application Process(Server Side)
Application Process(Server Side)
Server Agents Examples: Internet Information
Sever + http, Appachi + http
SQL query engines + http Communication Software
Examples: TCP, UDP; IP…
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-77
Application Software
Presentation
User Interface
Business (Application Logic)
Data (Database Access)
Layered Application ModelLayered Application Model
Client Part
Server Parts
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-88
Presentation: The client agent remains focused
on presenting information to or receiving
input from the user.
User Interface: User’s access to the application
logic via client agent. It can be dynamic and
configured by user. It is build on the top of the
user interface control. Dynamic User Interface:
• Customizing the look (example: www.cstore.com
• Customizing the content ( examples:
my.yahoo.com , www.exite.com )
Client PartClient Part
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Business Rules (Application Logic) Units of processing or algorithms that
represents concept of importance to the organization using database.
Data (Database Access) Logic to connect to database; access/manipulate data
held within databases.
Server PartsServer Parts
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1010
User InterfaceUser Interface
Presentation Presentation Business
(Application Logic)
Business (Application
Logic)
Database
Layered Application: Layered Application: 3-Tier Client/Server Model3-Tier Client/Server Model
Client Workstation(rich client)
Application Sever
Data (Data Access and Storage)
Data (Data Access and Storage)
CommunicationCommunicationNetworkNetwork
Mobile ClientWorkstation (thin client)
User InterfaceUser Interface
Presentation Presentation
Data Server
Run by Client AgentRuns by Application
Server Agent
Runs by Database Server Agent
Run by Client Agent
user
user
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1111
““Logical Tiers vs Physical TiersLogical Tiers vs Physical Tiers
Application Model Logical Tiers
• Presentation• User Interface• Business• Data
Physical Tiers• Client workstation• Application server• Data Base
Application Model Logical Tiers
• Presentation• User Interface• Business• Data
Physical Tiers• Client workstation• Application server• Data Base
PresentationClient WorkstationUser Interface
Business (Application Logic)
Application Server
Data (Database Access)
Database
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1212
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1313
Local ISP (LAN)Local ISP (LAN)
hub
Client
Printer
Server
Client
LAN Switch
Client
Remote Access ServerModem pools
TelephoneLines
Router
External Link
Serversmodem
modem
Client
modem
modem External LinkRouter
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1414
internet: network of networksinternet: network of networks
modem
modem
local ISP
companynetwork
mobile station
workstation
router
servermodem
regional ISP
local ISP
Base Station
links
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1515
InternetInternet
millions of connected computing devices: hosts, end-systems PCs workstations, servers, … Personal Data Assistances, phones, … running network apps
communication links fiber, copper, radio, satellite transmission rate = bandwidth
routers: forward packets
Networking Hardware and Software Protocols, Hubs, LAN Switches, Repeaters,
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1616
protocols control sending, receiving of messages e.g., TCP, IP, HTTP, FTP, PPP, …
Internet: “network of networks” loosely hierarchical public Internet versus private intranet
Internet standards (IAB) RFC: Request for comments IETF: Internet Engineering Task Force
InternetInternet
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human protocols: “what’s the time?” “I have a question” introductions
… specific msgs sent… specific actions
taken when msgs received, or other events
network protocols: machines rather than
humans all communication
activity in Internet governed by protocols
protocols define format, order of msgs sent and
received among network entities, and actions taken on msg transmission, receipt
What’s a protocol?
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1818
a human protocol and a computer network protocol:
Q: Other human protocols?
Hi
Hi
Got thetime?
2:00
TCP connection req
TCP connectionresponseGet http://www.awl.com/kurose-ross
<file>time
What’s a protocol?
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-1919
Examples? Search Engines (Google) Email (Hotmail) Shopping (Amazon) Auctions (eBay) Chat (AOL)
Internet ServicesInternet Services
Goals? Fast service (low latency) Service all users (scalability) Always available (fault tolerance)
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2020
the Internetthe Internetintranet
router
Intranet: access is denied from outside
firewall
A private corporate network consisting of hosts, routers, and networks that use TCP/IP technology. An intranet may or may not connect to the global Internet.
intranetintranet
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2121
Extranet: an internet of networkseach of which is belong to
individual company or organization
Company 1
Company 2
Company 3
extranetextranet
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IP addressing: ICANNIP addressing: ICANN
Q: How does an ISP get block of addresses and Names?
A: ICANN: (Internet Corporation For Assigned Names and Numbers) The organization that took over the IANA
duties after Postel’s death. IANA: (Internet Assigned Number Authority)
Essentially one individual (Jon Postel). IANA was originally responsible for assigning IP addresses and the constants used in TCP/IP protocols. Replaced by ICANN in 1999.
Q: How does an ISP get block of addresses and Names?
A: ICANN: (Internet Corporation For Assigned Names and Numbers) The organization that took over the IANA
duties after Postel’s death. IANA: (Internet Assigned Number Authority)
Essentially one individual (Jon Postel). IANA was originally responsible for assigning IP addresses and the constants used in TCP/IP protocols. Replaced by ICANN in 1999.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2323
IP addressing: ICANNIP addressing: ICANN
ICANN coordinates the assignment of identifiers that must be globally unique for the Internet to function. allocates addresses manages DNS assigns domain names, resolves disputes assigns default port numbers sets protocol parameter
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2424
(b)(b) USC-ISI Marina del Rey, CA
(l)(l) ICANN Marina del Rey, CA
(e) (e) NASA Mt View, CA(f)(f) Internet Software C. Palo Alto, CA
(i)(i) NORDUnet Stockholm, Sweden
(k)(k) RIPE London, UK
(m)(m) WIDE Tokyo, Japan
(a)(a) NSI Herndon, VA(c)(c) PSInet Herndon, VA
(d)(d) U Maryland College Park, MD(g)(g) DISA Vienna, VA
(h)(h) ARL Aberdeen, MD(j)(j) NSI (TBD) Herndon, VA
DNS Root ServersDNS Root Servers
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communication infrastructure enables distributed applications: Web, email, games,
e-commerce, database., file (MP3) sharing
communication services provided to apps: connectionless connection-oriented
modem
modem
local ISP
companynetwork
regional ISP
What’s the Internet: a service viewWhat’s the Internet: a service view
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2626
Chapter 1: OutlineChapter 1: Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edgeNetwork coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2727
Network StructureNetwork Structure
network edge: applications and hosts
network core: routers
access networks, physical media: communication
links
modem
modem
local ISP
companynetwork
regional ISP
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2828
The network edge:The network edge:
end systems (hosts): run application programs e.g. Web, email at “edge of network”
client/server model client host requests, receives
service from always-on server e.g. Web browser/server;
email client/server
peer-peer model: minimal (or no) use of
dedicated servers e.g. Gnutella, KaZaA
modem
modem
local ISP
companynetwork
regional ISP
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-2929
Client-ServerClient-Server
Application Softwaremodem
modem
1. Client-ServerClient Side SoftwareServer Side Software
2. Peer-to-Peer ! (chapter 2)
Client SideSoftware
Server SideSoftwarePeer Side
Peer Side
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3030
Server TypesServer Types
Web server File Server (example: Network File System) Database Server Application Server Groupware Server Software Server Object Server Proxy Server DNS Server
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3131
Network edge: connection-oriented serviceNetwork edge: connection-oriented service
Goal: data transfer between end systems
handshaking: setup (prepare for) data transfer ahead of time set up “state” in two
communicating hosts TCP - Transmission
Control Protocol Internet’s connection-
oriented service
TCP service [RFC 793] reliable, in-order byte-
stream data transfer loss: acknowledgements
and retransmissions flow control:
sender won’t overwhelm receiver
congestion control: senders “slow down
sending rate” when network congested
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Network edge: connectionless serviceNetwork edge: connectionless service
Goal: data transfer between end systems same as before!
UDP - User Datagram Protocol [RFC 768]: Internet’s connectionless service unreliable data
transfer no flow control no congestion
control
App’s using TCP: HTTP (Web), FTP (file
transfer), Telnet (remote login), SMTP (email)
App’s using UDP: streaming media,
teleconferencing, DNS, Internet telephony
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3333
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3434
The Network CoreThe Network Core
mesh of interconnected routers
the fundamental question: how is data transferred through net? circuit switching:
dedicated circuit per call: telephone net
packet-switching: data sent thru net in discrete “chunks”
modem
modem
local ISP
companynetwork
regional ISP
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Network Core: Circuit SwitchingNetwork Core: Circuit Switching
End-end resources reserved for “call”
link bandwidth, switch capacity
dedicated resources: no sharing
circuit-like (guaranteed) performance
call setup required
modem
modem
local ISP
companynetwork
regional ISP
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3636
Network Core: Circuit SwitchingNetwork Core: Circuit Switching
network resources (e.g., bandwidth) divided into “pieces”
pieces allocated to calls
resource piece idle if not used by owning call (no sharing)
dividing link bandwidth into “pieces” frequency division time division
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3737
FDMA
frequency
time
TDMA
frequency
time
4 users
Example:
Circuit Switching: TDMA and TDMA
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3838
each end-end data stream divided into packets
user A, B packets share network resources
each packet uses full link bandwidth
resources used as needed
resource contention: aggregate resource
demand can exceed amount available
congestion: packets queue, wait for link use
store and forward: packets move one hop at a time transmit over link wait turn at next
link
Bandwidth division into “pieces”
Dedicated allocationResource reservation
Network Core: Packet Switching
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-3939
Packet Switching: Statistical MultiplexingPacket Switching: Statistical Multiplexing
Sequence of A & B packets does not have fixed pattern statistical multiplexing.
In TDM each host gets same slot in revolving TDM frame.
Sequence of A & B packets does not have fixed pattern statistical multiplexing.
In TDM each host gets same slot in revolving TDM frame.
A
B
C10 MbsEthernet
1.5 Mbs
D E
statistical multiplexing
queue of packetswaiting for output
link
emptybuffer
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Packet switching versus circuit switchingPacket switching versus circuit switching
Each user: sends 100 kbps when
“active” is active p=10% of time
Each user: sends 100 kbps when
“active” is active p=10% of time
Packet switching allows more users to use network!Packet switching allows more users to use network!
User: 1
1 Mbps link
User: N
Switch
Circuit-Switch ≤ 10 simultaneous usersCircuit-Switch ≤ 10 simultaneous users
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How many Users?
)!(!
!
)1(),;(
kNk
N
k
N: whichin
ppk
NpNkP kNk
)!(!
!
)1(),;(
kNk
N
k
N: whichin
ppk
NpNkP kNk
binomial distribution: The probability that k users be active together:
35
11
( 10) ( ;35,0.1) 0.0017
( 10) 1 0.0017 0.9983k
P k P k
P k
Packet-Switch if N=35 users, for active users > 10
there is: probability < 0.0017 for active users <=
10 there is: probability > 0.9983
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4242
Packet Switching UsersPacket Switching Users
Switch supports 35 simultaneous users (connections) Up to 10 users be active: no queue, packet
switching has almost the same delay performance as circuit switching.
More than 10 users be active: output queue begin to grow and the connections experience queuing delay.
Because the probability of having 11 or more simultaneous active users is 0.0017,almost the same delay performance as circuit switching.
Packet switching allows more than 3 times the number of users.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4343
Packet switching versus circuit switchingPacket switching versus circuit switching
Great for bursty data resource sharing simpler no call setup
Excessive congestion: packet delay and loss protocols needed for reliable data transfer,
congestion control Q: How to provide circuit-like behavior?
bandwidth guarantees needed for audio/video applications.
still an unsolved problem (chapter 6)
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4444
Packet-switching: store-and-forwardPacket-switching: store-and-forward
Takes L/R seconds to transmit (push out) packet of L bits on to link or R bps
Entire packet must arrive at router before it can be transmitted on next link: store and forward
delay = 3L/R
Example: L = 7.5 Mbits;
message size R = 1.5 Mbps; link
bandwidth message
transmission time = L/R = 5 sec
delay = 3L/R = 15 sec
R R R
L
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Packet Switching: Message SegmentingPacket Switching: Message Segmenting
Now break up the message into 5000 packets
Each packet 1,500 bits
1 msec to transmit packet on one link
pipelining: each link works in parallel
Delay reduced from 15 sec to 5.002 sec
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Packet-switched networks: forwardingPacket-switched networks: forwarding
Goal: move packets through routers from source to destination we’ll study several path selection (i.e.
routing)algorithms (chapter 4) datagram network:
destination address in packet determines next hop routes may change during session
virtual circuit network: each packet carries tag (virtual circuit ID), tag
determines next hop fixed path determined at call setup time, remains fixed
thru call routers maintain per-call state
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4747
Network TaxonomyNetwork Taxonomy
Telecommunicationnetworks
Telecommunicationnetworks
Circuit-switchednetworks
Circuit-switchednetworks
FDMFDM TDMTDM
Packet-switchednetworks
Packet-switchednetworks
Networkswith VCsNetworkswith VCs
DatagramNetworksDatagramNetworks
Datagram network is not either connection-oriented or connectionless. Internet provides both connection-oriented (TCP) and connectionless services (UDP) to applications.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4848
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-4949
Access networks and physical mediaAccess networks and physical media
Q: How to connection end systems to edge router?
residential access nets institutional access
networks (school, company)
mobile access networks
Keep in mind: bandwidth (bits per
second) of access network?
shared or dedicated?
modem
modem
local ISP
companynetwork
regional ISP
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Residential access: point to point Residential access: point to point accessaccess
Dialup via modem up to 56Kbps direct access
to router (often less) Can’t surf and phone at
same time: can’t be “always on”
ADSL: asymmetric digital subscriber line up to 1 Mbps upstream (today typically < 256
kbps) up to 8 Mbps downstream (today typically < 1
Mbps) FDM: 50 kHz - 1 MHz for downstream 4 kHz - 50 kHz for upstream 0 kHz - 4 kHz for ordinary telephone
modem
modem
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Company access: local area networksCompany access: local area networks
company/univ local area network (LAN) connects end system to edge router
Ethernet: shared or dedicated
link connects end system and router
10 Mbs, 100Mbps, Gigabit Ethernet
deployment: institutions, home LANs happening now
LANs: chapter 5
modem
modem
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Wireless access networksWireless access networks
shared wireless access network connects end system to router via base station aka
“access point” wireless LANs:
802.11b (WiFi): 11 Mbps wider-area wireless
access provided by telco operator 3G ~ 384 kbps
• Will it happen?? WAP/GPRS in Europe
shared wireless access network connects end system to router via base station aka
“access point” wireless LANs:
802.11b (WiFi): 11 Mbps wider-area wireless
access provided by telco operator 3G ~ 384 kbps
• Will it happen?? WAP/GPRS in Europe
basestation
mobilestations (hosts)
router
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-5959
Home networksHome networks
Typical home network components: ADSL or cable modem router/firewall/NAT Ethernet wireless access point
(Network Address Translation) A technology that allows hosts with private addresses to communicate with an outside network such as the global Internet.
wireless access point
wirelesslaptops
router/Firewall/NAT
cable modem
to/fromInternet
Ethernet (switched)
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Physical (Transmission) Media-LinkPhysical (Transmission) Media-Link
Physical Media (link) : what lies between transmitter & receiver.Physical Media (link) : what lies between transmitter & receiver.
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Twisted PairTwisted Pair
Twisted Pair (TP) Unshielded/Shielded UTP/STP
Category 3: traditional phone wires, 10 Mbps Ethernet
Category 5 TP: 100Mbps Ethernet
…
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Physical Media: coax, fiberPhysical Media: coax, fiber
Coaxial cable: two concentric copper
conductors bidirectional baseband:
single channel on cable legacy Ethernet
broadband: multiple channel on
cable HFC
Fiber optic cable: glass fiber carrying
light pulses, each pulse a bit
high-speed operation: high-speed point-to-point
transmission (e.g., 5 Gps) low error rate:
repeaters spaced far apart ; immune to electromagnetic noise
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Physical media: radioPhysical media: radio
signal carried in electromagnetic spectrum
no physical “wire” bidirectional propagation
environment effects: reflection obstruction by objects interference
Radio link types: terrestrial microwave
e.g. up to 45 Mbps channels
LAN (e.g., WaveLAN) 2Mbps, 11Mbps
wide-area (e.g., cellular) e.g. 3G: hundreds of
kbps satellite
up to 50Mbps channel (or multiple smaller channels)
270 msec end-end delay geosynchronous versus
LEOS
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Delay Latency for propagating data along the link Corresponds to the “length” of the link Typically measured in seconds
Bandwidth (Capacity) Amount of data sent (or received) per unit time Corresponds to the “capacity” of the link Typically measured in bits per second
Bandwidth(Bps)
Delay(sec)
delay x bandwidth(bit)
Links: Delay and BandwidthLinks: Delay and Bandwidth
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-6565
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
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Tier Definition-Tier 1Tier Definition-Tier 1
Tier 1 providers make settlement-free interconnection arrangements with other Tier 1 providers, in which the two networks agree to carry each other's traffic (so-called "peering" with one another) at no cost.
No Tier 1 carriers have to pay for IP transit to any other Tier 1, and in general all other ISPs directly or indirectly pay the Tier 1s for access to their networks.
Tier 1 providers own the physical medium over which information is carried, as well as the network equipment which manages that information.
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Tier 1 IPv4 ISPsTier 1 IPv4 ISPs
The following are believed to be the only Tier 1 ISPs worldwide:1. AOL Transit Data Network (ATDN)-AS 1668 2. AT&T-AS 7018 (not 2685, 2686, 2687, 2688 or 7132) 3. Global Crossing (GX)-AS 3549 4. Level 3-AS 3356 5. Verizon Business (UUnet)-AS 701 (not 702, 703 or 19262) 6. Nippon Telegraph and Telephone Corp. (NTT)-AS 2914 7. Qwest-AS 209
8. SAVVIS (Cable & Wireless America)-AS 3561
9. Sprint Nextel Corporation-AS 1239 • In the Internet, an autonomous system (AS) is a collection of IP
networks and routers under the control of one entity (or sometimes more) that presents a common routing policy to the Internet. See RFC 1930 for additional detail on this updated definition.
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UUNET US backbone network
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Tier-1 ISPs InterconnectionTier-1 ISPs Interconnection
9
11
22
33
4
Topology: Full MeshData Rates: 622Mbps, 2.5-10Gbps
▪▪▪
▪▪▪
▪▪▪
▪▪▪
▪▪▪
NAPs
NAPs
NAPs
NAPs
NAPs
NA
P:
Netw
ork
Acc
ess
Poin
t
Tier-2 ISPsTier-2 ISPs
High Speed Link from Telecom Companies
1. NSF 1988 ,T12. ANS 1993 ,T3
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7070
Tier Definition-Tier 2, 3Tier Definition-Tier 2, 3
There is no formal interconnection hierarchy, lower-tier companies are divided into two categories: Tier 2 - A network who peers with other networks,
but still pays for transit to reach some portion of the Internet.
Tier 3 - A network who solely purchases transit from other networks to reach the Internet.
Many of Tier 2 and 3 companies are very large Internet providers, but since they purchase IP transit from other networks they are not considered Tier 1.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7171
▪▪▪▪NAPs
Tier-2 Tier-2 ISPISP Tier-2 Tier-2
ISPISP
Tier-1 Tier-1 ISPISP
Access ISP
Access ISP
Servers modem
Com3
RAS+
Modem Pool
modem
Tier-2 ISPs / Access ISPsTier-2 ISPs / Access ISPs
Remote Clients
Clients
▪▪▪ To Tier-1 ISP
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7272
Tier-1 ISP: e.g., UUNETTier-1 ISP: e.g., UUNET
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7373
Internet structure: network of networksInternet structure: network of networks
roughly hierarchical at center: “tier-1” ISPs (e.g., UUNet, BBN/Genuity,
Sprint, AT&T), national/international coverage treat each other as equals
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
Tier-1 providers interconnect (peer) privately
NAP
Tier-1 providers also interconnect at public network access points (NAPs)
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7474
Internet structure: network of networksInternet structure: network of networks
“Tier-2” ISPs: smaller (often regional) ISPs Connect to one or more tier-1 ISPs, possibly other tier-2 ISPs
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
NAP
Tier-2 ISPTier-2 ISP
Tier-2 ISP
Tier-2 ISP
Tier-2 ISP pays tier-1 ISP for connectivity to rest of Internet tier-2 ISP is customer oftier-1 provider
Tier-2 ISPs also peer privately with each other, interconnect at NAP
Tier-2 ISP
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7575
Internet structure: network of networksInternet structure: network of networks
“Tier-3” ISPs and local ISPs last hop (“access”) network (closest to end systems)
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
NAP
Tier-2 ISPTier-2 ISP
Tier-2 ISP Tier-2 ISP
Tier-2 ISP
localISPlocal
ISPlocalISP
localISP
localISP Tier 3
ISP
localISP
localISP
localISP
Local and tier- 3 ISPs are customers ofhigher tier ISPsconnecting them to rest of Internet
Internet Internet Connection Connection Providers Providers (ICPs)(ICPs)For local ISPsFor local ISPs
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7676
End to End CommunicationEnd to End Communication
Tier 1 ISP
Tier 1 ISP
Tier 1 ISP
NAP
Tier-2 ISPTier-2 ISP
Tier-2 ISP Tier-2 ISP
Tier-2 ISP
AccessISPAccess
ISPAccess
ISP
AccessISP
AccessISP Tier 3
ISP
AccessISP
AccessISP
AccessISP
a packet passes through many networks!
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7777
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7878
How do loss and delay occur?How do loss and delay occur?
packets queue in router buffers packet arrival rate to link exceeds output link capacity packets queue, wait for turn
A
B
packet being transmitted (delay)
packets queue (delay)
free (available) buffers: arriving packets dropped (loss) if no free buffers
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-7979
Four sources of packet delayFour sources of packet delay
1. nodal processing: check bit errors determine output link
A
B
propagation
transmission
nodalprocessing queue
2. queueing time waiting at output
link for transmission depends on
congestion level of router
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8080
Delay in packet-switched networksDelay in packet-switched networks
3. Transmission delay: R=link bandwidth (bps) L=number of bits in
packet (bits) time to send bits into
link = L/R
4. Propagation delay: d = length of physical
link s = propagation speed
in medium (~2x108 m/sec)
propagation delay = d/s
A
B
propagation
transmission
nodalprocessing queue
Note: s and R are verydifferent quantities!
Note: s and R are verydifferent quantities!
bit length: s/R [m]packet length: Ls/R
[m]
bit length: s/R [m]packet length: Ls/R
[m]
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8181
Caravan analogyCaravan analogy
car=bit caravan = packet cars speed (km/hr) = propagation speed (m/sec) service rate at toll booth (car/sec) = bandwidth
(bit/sec)
ten-car caravan 120
km
toll booth22331010
11 toll booth
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8282
Caravan Analogy (cont.)Caravan Analogy (cont.)
cars speed = 120 km/hr = 2km/mintoll booth takes 12 sec to service a car ( car/sec)
Q: How long until caravan is lined up before 2nd toll booth?
Time to “push” entire caravan through toll booth onto highway = 12*10 = 120sec = 2min
Time for last car to propagate from 1st to 2nd toll both: 120km/(120km/hr)= 1 hr
A: 62 minutes
121
120 km
toll booth22331010
11toll booth
4km
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8383
Caravan Analogy (cont.)Caravan Analogy (cont.)
Q: Will cars arrive to 2nd booth before all cars serviced at 1st booth?
After (1+6) min, 1st car at 2nd booth and 3 cars still at 1st booth.
1st bit of packet can arrive at 2nd router before packet is fully transmitted at 1st router!
cars speed = 1200 km/hr = 20km/mintoll booth takes 1min to service a car ( 1
car/min)
120 km 2233
99
11toll booth6688 77
toll booth
20km20km
1010
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8484
Bit LengthBit Length
bit length = s/R Packet length = Ls/R
s = propagation speed of energy in the link (medium) [m/sec]
R = link bandwidth [bps] L = number of bits in packet [bits]
Example : s= 200m/µs; R=10Mbps [Tbit =0.1 µs]; L= 250 Byte = 2000 bit
20m
linksource destination
Propagation direction
20
00 1
99
9
1234
20×2000 m
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8585
Nodal delayNodal delay
dproc = processing delay typically a few msecs or less
dqueue = queuing delay depends on congestion
dtrans = transmission delay = L/R, significant for low-speed links
dprop = propagation delay a few microsecs to hundreds of msecs
proptransqueueprocnodal ddddd
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8686
Queuing delay (revisited)Queuing delay (revisited)
R=link bandwidth (bps) L=packet length (bits) a=average packet
arrival rate
traffic intensity = La/R
La/R ~ 0: average queuing delay small La/R —> 1: delays become large La/R > 1: more “work” arriving than can
be serviced, average delay infinite!
La/R
Avera
ge q
ueuin
g d
ela
y
1
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8787
““Real” Internet delays and routesReal” Internet delays and routes
What do “real” Internet delay & loss look like? Traceroute program: provides delay
measurement from source to router along end-end Internet path towards destination. For all i: sends three packets that will reach router i on path
towards destination router i will return packets to sender sender times interval between transmission and reply.
3 probes
3 probes
3 probes
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8888
““Real” Internet delays and routesReal” Internet delays and routes
1 cs-gw (128.119.240.254) 1 ms 1 ms 2 ms2 border1-rt-fa5-1-0.gw.umass.edu (128.119.3.145) 1 ms 1 ms 2 ms3 cht-vbns.gw.umass.edu (128.119.3.130) 6 ms 5 ms 5 ms4 jn1-at1-0-0-19.wor.vbns.net (204.147.132.129) 16 ms 11 ms 13 ms 5 jn1-so7-0-0-0.wae.vbns.net (204.147.136.136) 21 ms 18 ms 18 ms 6 abilene-vbns.abilene.ucaid.edu (198.32.11.9) 22 ms 18 ms 22 ms7 nycm-wash.abilene.ucaid.edu (198.32.8.46) 22 ms 22 ms 22 ms8 62.40.103.253 (62.40.103.253) 104 ms 109 ms 106 ms9 de2-1.de1.de.geant.net (62.40.96.129) 109 ms 102 ms 104 ms10 de.fr1.fr.geant.net (62.40.96.50) 113 ms 121 ms 114 ms11 renater-gw.fr1.fr.geant.net (62.40.103.54) 112 ms 114 ms 112 ms12 nio-n2.cssi.renater.fr (193.51.206.13) 111 ms 114 ms 116 ms13 nice.cssi.renater.fr (195.220.98.102) 123 ms 125 ms 124 ms14 r3t2-nice.cssi.renater.fr (195.220.98.110) 126 ms 126 ms 124 ms15 eurecom-valbonne.r3t2.ft.net (193.48.50.54) 135 ms 128 ms 133 ms16 194.214.211.25 (194.214.211.25) 126 ms 128 ms 126 ms17 * * *18 * * *19 fantasia.eurecom.fr (193.55.113.142) 132 ms 128 ms 136 ms
traceroute: gaia.cs.umass.edu to www.eurecom.frThree delay measements from gaia.cs.umass.edu to cs-gw.cs.umass.edu
* means no reponse (probe lost, router not replying)
trans-oceaniclink
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-8989
Packet LossPacket Loss
queue (aka buffer) preceding link in buffer has finite capacity
when packet arrives to full queue, packet is dropped (aka lost)
lost packet may be retransmitted by previous node, by source end system, or not retransmitted at all
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9090
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9191
Network ModelsNetwork Models
The network model is defined in 3-D space.
App. Software (User) Plane: Data Communication.
Control Plane: Connection setup and
connection Maintenance, Resources access control
and access level control. Management Plane: Measurement and
management of network performance.
App. Software (User) Plane:Data Communication.
App. Software (User) Plane:Data Communication.
App. SoftwareApp. Software(User)(User)PlanePlane
Figure: Network Model.
We study this part only!We study this part only!
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9393
Why layering?Why layering?
Dealing with complex systems: explicit structure allows identification,
relationship of complex system’s pieces layered reference model for discussion
modularization eases maintenance, updating of system change of implementation of layer’s service
transparent to rest of system e.g., change in gate procedure doesn’t
affect rest of system layering considered harmful?
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9494
What’s a protocol?What’s a protocol?human protocols: “what’s the time?” “I have a question” introductions
… specific msgs sent… specific actions
taken when msgs received, or other events
network protocols: machines rather than
humans all communication
activity in Internet governed by protocols
Protocols defines: format, order of msgs sent
and received among network entities, and
actions taken on msg transmission, reception.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9595
Protocols (stack)Protocols (stack)
Distributed Systems relies on communicating elements.
Communicating elements follow a set of rules, syntax and semantics, i.e. Protocol.
In other words: A protocol governs the co-operation of two remote
parties (elements), or Two elements, remote to each other, do together a
task using a predefined rules, syntax, and semantics. Protocol Stack: It is a set of protocols,
designed to govern entire network.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9696
Internet Layering Model and Internet Layering Model and ProtocolsProtocols
Application: supporting network applications FTP, SMTP, HTTP
Transport: host-host data transfer TCP, UDP
Network: routing of datagrams from source to destination IP, routing protocols
Link: data transfer between neighboring network elements PPP, Ethernet
Physical: Putting bits “on the wire”
application
transport
network
link
physical
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9797
Layers and AddressesLayers and Addresses
Application Layer domain name e.g. www.shahroodut.ac.ir
Transport Layer the identity of the application in the
destination host Port number: 2 bytes e.g. 80
Network Layer the network identity of the destination
host IP address: 4 bytes for IPv4 e.g. 202.156.1.78
Link Layer the identity of network interface card MAC address (physical address): 6 bytes e.g. 00-04-23-5E-6A-93
Application Layer domain name e.g. www.shahroodut.ac.ir
Transport Layer the identity of the application in the
destination host Port number: 2 bytes e.g. 80
Network Layer the network identity of the destination
host IP address: 4 bytes for IPv4 e.g. 202.156.1.78
Link Layer the identity of network interface card MAC address (physical address): 6 bytes e.g. 00-04-23-5E-6A-93
application
transport
network
link
physical
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9898
Open Systems Interconnection model (International Standard Organization-ISO, UN)
OSI model vs TCP/IP modelOSI model vs TCP/IP model
application
transport
network
link
physical
application
transport
network
networkinterface
application
presentation
Session
transport
network
Link
physical
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-9999
Layering and DataLayering and Data
Each layer takes data from above adds header information to create new data unit passes new data unit to layer below
PDUs: frame, datagram (packet), segment, messagePDUs: frame, datagram (packet), segment, message
applicationtransportnetwork
linkphysical
Source process
applicationtransportnetwork
linkphysical
Destination process
message
segment
datagram
frame
M
M HtHnHl Tl
M HtHn
M Ht
M
M HtHnHl Tl
M HtHn
M Ht
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-100100
Layering and ProtocolLayering and Protocol
Appl. Soft. Appl. Soft.
App. Layer Protocols(ftp, http, SMTP, …)
Transport LayerProtocol (TCP, UDP)
Network LayerProtocols (IP, OSPF, RSVP)
Link LayerProtocols (Ethernet, FDDI, …)
application
transport
network
link
physical
application
transport
network
link
physicalPhysical Layer
Protocols (Ethernet, FDDI, …)
Physical Communication Channel
NETWORKNETWORK
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-101101
Protocol layering and dataProtocol layering and data
Ht
Message App. ProcessApp. Process
applicationHa
Message
transport Ht Ht
Ht
network
App. Process decides to send a message to its counterpart
App. Layer adds its header, sends the message to transport layer
Transport layer breaks down the message into several parts, add its header to each part And makes segments.It sends one-by-one segments to network layer
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-102102
Protocol Data UnitsProtocol Data Units
message[mes/sec]
Segment[seg/sec]
Datagram[Packet/sec]
Frame[frame/sec]
application
transport
network
link
physical
Appl. Soft.
application
transport
network
link
physical
Appl. Soft.[tps], [HTTPops/s],[NFS IOPS]
1st layer PDU(physical frame)
[bps]
Physical Communication Channel[Baud], [Hz]
Bau
d =
ch
an
ges
in s
ign
al/se
cB
au
d =
ch
an
ges
in s
ign
al/se
c
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-103103
Network Network BandwidthBandwidth, , ThroughputThroughput and and GoodputGoodput
Application Layer
Transport Layer
Network Layer
Link Layer
Physical layer
Bandwidth Throughput Goodput
Tps, HTTPops/s,
…
Segmant/s
Packet/s Frame/s
Bit/s
Bandwidth: The rate at which the data units can be transmitted.
Throughput: The rate at which the data units are delivered (transferred).
It is a function of load. Its upper-band is Bandwidth.
Goodput: The rate at which the useful data units are delivered (transferred).
Its upper-band is the Throughput.
Bandwidth: The rate at which the data units can be transmitted.
Throughput: The rate at which the data units are delivered (transferred).
It is a function of load. Its upper-band is Bandwidth.
Goodput: The rate at which the useful data units are delivered (transferred).
Its upper-band is the Throughput.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-104104
Throughput, Goodput vs LoadThroughput, Goodput vs Load
Goodput
Throughput
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-105105
Example: Network Layer GoodputExample: Network Layer Goodput
Goodput:
Efficiency:
link. congestion-no and packet, corupted-no packet, loss-no
:of condition in goodput goodput Optimum
[bps] goodput optimum
[bps] goodputEfficiency
[sec] duration time recieving
[bit] packet per length payloadreplica) recieved - packets recievedsbGoodput
100
(]/[
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-106106
Protocols/ServicesProtocols/Services
application
transport
network
link
physical
Data Transport Services
Application Program Services
Hop-to-Hopprotocols
End-to-Endprotocols
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-107107
From Application ViewpointFrom Application Viewpoint
Application Program Interface (API)
Communication Software & HardwarePlatform (OS + Hardware)
Application SoftwareApplication Software
APIAPI
App. SoftwareApp. Software
transportnetwork
linkphysical
application
Controlledby OS
Controlledby App. Soft.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-108108
Layering: Physical Communication Layering: Physical Communication
applicationtransportnetwork
linkphysical
modem
modem
networklink
physical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
data
data
Host A
Host B
Router R
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-109109
Layering: Logical Communication-1 Layering: Logical Communication-1
Each layer: distributed “entities”
implement layer functions at each node
entities perform actions, exchange messages with peers
applicationtransportnetwork
linkphysical
modem
modem
networklink
physical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-110110
Layering: LogicalLayering: Logical Communication Communication
E.g.: transport take data from
app add addressing,
reliability check info to form “datagram”
send datagram to peer
wait for peer to ack receipt
analogy: post office
applicationtransportnetwork
linkphysical
modem
modem
networklink
physical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
applicationtransportnetwork
linkphysical
data
data
transport
data
transport
ack
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-111111
TCP/IP protocol stackTCP/IP protocol stack
mimemime
ftpftp httphttp smtpsmtp telnettelnet snmpsnmp tftptftp rtprtp dnsdns ……
Transmission Control Pr. (TCP)
Transmission Control Pr. (TCP)
User Datagram Pr. (UDP)User Datagram Pr. (UDP)
icmpicmp ospfospfrsvprsvp igmpigmp
Ethernet, token ring, FDDI, ATM, Frame relay, SNA, X25Ethernet, token ring, FDDI, ATM, Frame relay, SNA, X25
domain name service
real time pr.trival file transfer pr.
simple network management pr.
ftp: file transfer protocolhttp; hypertext transfer protocolSmtp: simple mail transfer protocolMime: multipurose Internet mail extensionstelnet=virtual terminal
icmp: Internet control message protocolospf: open shortest path first protocolrsvp: resource reservation protocoligmp: Internet group management protocol
arparp rarprarpInternet Protocol (IP)Internet Protocol (IP)
arp: address resolution protocolrarp: reverse address resolution protocol
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-112112
Chapter 1 OutlineChapter 1 Outline
1.0 Why Networking1.1 What is the Internet?1.2 Network Structure
Network edge
Network coreNetwork access and physical media
1.3 Internet structure and ISPs 1.4 Delay & loss in packet-switched networks1.5 Protocol layers, service models1.6 History
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-113113
Internet Host CountInternet Host Count
Internet Systems Consortium, Inc. (ISC) is a nonprofit corporation
dedicated to supporting the infrastructure of the universal connected self-organizing Internet and
has autonomy to participates by developing and maintaining core production quality software, protocols, and operations.
Internet Systems Consortium, Inc. (ISC) is a nonprofit corporation
dedicated to supporting the infrastructure of the universal connected self-organizing Internet and
has autonomy to participates by developing and maintaining core production quality software, protocols, and operations.
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-114114
Internet Standard: RFCsInternet Standard: RFCs
Introduction Year
RF
C N
umbe
rs
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-115115
Internet HistoryInternet History
1961: Kleinrock - queueing theory shows effectiveness of packet-switching
1964: Baran - packet-switching in military nets
1967: ARPAnet conceived by Advanced Research Projects Agency
1969: first ARPAnet node operational
1972: ARPAnet
demonstrated publicly
NCP (Network Control Protocol) first host-host protocol
first e-mail program ARPAnet has 15
nodes
1961-1972: Early packet-switching principles1961-1972: Early packet-switching principles
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-116116
Internet HistoryInternet History
1970: ALOHAnet satellite network in Hawaii
1973: Metcalfe’s PhD thesis proposes Ethernet
1974: Cerf and Kahn - architecture for interconnecting networks
late70’s: proprietary architectures: DECnet, SNA, XNA
late 70’s: switching fixed length packets (ATM precursor)
1979: ARPAnet has 200 nodes
Cerf and Kahn’s internetworking principles: minimalism, autonomy
- no internal changes required to interconnect networks
best effort service model
stateless routers decentralized control
define today’s Internet architecture
1972-1980: Internetworking, new and proprietary nets1972-1980: Internetworking, new and proprietary nets
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-117117
Internet HistoryInternet History
1983: deployment of TCP/IP
1982: SMTP e-mail protocol defined
1983: DNS defined for name-to-IP-address translation
1985: FTP protocol defined
1988: TCP congestion control
new national networks: Csnet, BITnet, NSFnet, Minitel
100,000 hosts connected to confederation of networks
new national networks: Csnet, BITnet, NSFnet, Minitel
100,000 hosts connected to confederation of networks
1980-1990: new protocols, a proliferation of networks1980-1990: new protocols, a proliferation of networks
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-118118
Internet HistoryInternet History
Early 1990’s: ARPAnet decommissioned
1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)
early 1990s: Web hypertext [Bush 1945,
Nelson 1960’s] HTML, HTTP: Berners-Lee 1994: Mosaic, later
Netscape late 1990’s:
commercialization of the Web
Late 1990’s – 2000’s:
more killer apps: instant messaging, peer2peer file sharing (e.g., Naptser)
network security to forefront
est. 50 million host, 100 million+ users
backbone links running at Gbps
1990, 2000’s: commercialization, the Web, new apps1990, 2000’s: commercialization, the Web, new apps
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-119119
References & LinksReferences & Links
Complimentary Hyperlinks This part provides hyperlinks to interesting
(and hopefully useful) computer-networking resources. Most of these resources provide complimentary information to the material in chapter 1. If you're asked to write a paper pertaining to a specialized topic in computer networking, these resources should serve as a good starting point for your research.
References and Hyperlinks
ali.dmohammadi@ gmail.comali.dmohammadi@ gmail.com OrientationOrientation 1-1-120120
Complimentary Hyperlinks 1Complimentary Hyperlinks 1
IEEE History Center http://www.ieee.org/organizations/history_center/oral_histories/comsoc_oh.html.
Oral Histories that have been collected to commemorate the 50th Anniversary of the IEEE Communications Society. A number of interesting interviews with pioneers in the field.
International Engineering Consortium: Web ProForum Tutorials http://www.iec.org/online/tutorials/
More than 150 tutorials on communications and networking topics, with a focus on cutting edge technology. The tutorials vary in terms of their technical depth, but many are outstanding, and all are extremely well-written and very readable. This is the first place we look when looking for an on-line survey or tutorial.
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Broadband: Bringing home the bits http://www.nap.edu/html/broadband Extensive report on the importance and future of
residential broadband access from the Computer Science And Telecommunications Board, National Research Council, January 2002
Webopedia http://www.pcwebopaedia.com/ Online dictionary for computer and Internet
technology
Internet Economics http://china.si.umich.edu/telecom/net-economics.html Comprehensive index for resources relating to
Internet economics, including regulation and pricing.
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traceroute.org http://www.traceroute.org/ As discussed in Section 1.6, Traceroute provides routes and packet
delays between pairs of hosts in the Internet. This site gives you direct access to hundreds of source hosts from which you can trace routes to arbitrary destination hosts. Choose a country, a source host in that country, and any destination host -- then see how the packets weave their way through the Internet.
Internet Engineering Task Force (IETF) http://www.ietf.org/
The IETF is an open international community concerned with the development and operation of the Internet and its architecture. The IETF was formally established by the Internet Architecture Board (IAB), http://www.isi.edu/iab, in 1986. The IETF meets three times a year; much of its ongoing work is conducted via mailing lists by working groups. Typically, based upon previous IETF proceedings, working groups will convene at meetings to discuss the work of the IETF working groups. The IETF is administered by the Internet Society, http://www.isoc.org/, whose Web site contains lots of high-quality, Internet-related material.
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Henning Schulzrinne's Internet Technical Resources http://www.cs.columbia.edu/~hgs/internet Henning Schulzrinne has an extensive - although not
always current - index of online resources for the Internet.
The Association for Computing Machinery (ACM) http://www.acm.org/ A major international professional society that has
technical conferences, magazines, and journals in the networking area. The ACM Special Interest Group in Data Communications (SIGCOMM), http://www.acm.org/sigcomm, is the group within this body whose efforts are most closely related to networking
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The Institute of Electrical and Electronics Engineers (IEEE) http://www.ieee.org/
The other major international professional society that has technical conferences, magazines, and journals in the networking area. The IEEE Communications Society, http://www.comsoc.org/, and the IEEE Computer Society, http://www.computer.org/, are the groups within this body whose efforts are most closely related to networking.
The SETI@home Project http://setiathome.ssl.berkeley.edu/ As discussed in Section 1.2, the SETI@home project is a scientific
experiment that uses Internet-connected computers to search for extraterrestrial intelligence. You can download the SETI program directly from this site.
Nerds 2.0.1 A Brief History of the Internet http://www.pbs.org/opb/nerds2.0.1
This is the Web site for the highly entertaining and informative PBS video on the history of the Internet. The PBS video, Triumph of the Nerds, about the history of personal computers, is also recommended.
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Leonard Kleinrock's Personal History of the Internet http://www.lk.cs.ucla.edu/LK/Inet/birth.html
Professor Leonard Kleinrock made numerous important contributions to Internet technology and to the field of computer networking. This page provides his own interesting and highly entertaining description of the early history of the Internet.
The DSL Forum http://www.dslforum.org/ DSL Forum is a consortium of nearly 250 leading industry players
covering telecommunications, equipment, computing, networking and service provider companies. The site is rich in information about developments in digital subscriber loop and broadband access to the home.
Cable-modems.org http://www.cable-modems.org/ This site has many tutorials on cable modems, hybrid fiber-coax,
and related topics. Also includes reviews of cable modem products.
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A note on Internet Request for Comments (RFCs): Copies of Internet RFCs are maintained at multiple sites. The RFC URLs below all point into the RFC archive at the Information Sciences Institute (ISI), maintained the the RFC Editor of the Internet Society (the body that oversees the RFCs). Other RFC sites include http://www.faqs.org/rfc, http://www.pasteur.fr/other/computer/RFC (located in France), and http://www.csl.sony.co.jp/rfc/ (located in Japan).
Internet RFCs can be updated or obsoleted by later RFCs. We encourage you to check the sites listed above for the most up-to-date information. The RFC search facility at ISI, http://www.rfc-editor.org/rfcsearch.html, will allow you to search for an RFC and show updates to that RFC.
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References and Hyperlinks 1References and Hyperlinks 1
[@Home 1998] @Home, "Frequently Asked Questions," http://www.home.com/qa.html.
[Abramson 1970] N. Abramson, "The Aloha System--Another Alternative for Computer Communications," Proceedings of Fall Joint Computer Conference, AFIPS Conference, p. 37, 1970.
[ADSL 1998] ADSL Forum, "ADSL Tutorial," http://www.adsl.com/adsl_tutorial.html
[Almanac 1998] Computer Industry Almanac, http://www.c-i-a.com/
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References and Hyperlinks 2References and Hyperlinks 2
[AT&T Apps 1998] AT&T, "Killer Apps," http://www.att.com/technology/forstudents/brainspin/networks/killerapps.html
[AT&T Bandwidth 1999] AT&T, "Bandwidth: The Need for Speed," http://www.att.com/technology/forstudents/brainspin/networks/bandwidth/game.html
[AT&T Optics 1999] AT&T, "What are fiber optics?," http://www.att.com/technology/forstudents/brainspin/fiberoptics/
[Baran 1964] P. Baran, "On Distributed Communication Networks," IEEE Transactions on Communication Systems, Mar. 1964. Rand Corporation Technical report with the same title (Memorandum RM-3420-PR, 1964). http://www.rand.org/publications/RM/RM3420/
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[Berners-Lee 1989] T. Berners-Lee, CERN, "Information Management: A Proposal," Mar. 1989, May 1990. http://www.w3.org/History/1989/proposal.html
[Bertsekas 1991] D. Bertsekas and R. Gallagher, Data Networks, 2nd Ed. , Prentice Hall, Englewood Cliffs, NJ, 1991.
[Bush 1945] V. Bush, "As We May Think," The Atlantic Monthly, July 1945. http://www.theatlantic.com/unbound/flashbks/computer/bushf.htm
[Cable 1998] Cable Data News, "Overview of Cable Modem Technology and Services," 1998. http://www.cabledatacomnews.com/cmic/cmic1.html
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[Cerf 1974] V. Cerf and R. Kahn, "A Protocol for Packet Network Interconnection," IEEE Transactions on Communications Technology, Vol. COM-22, No. 5, pp. 627-641.
[Cisco LAN 1998] Cisco Systems Inc., "Designing Switched LAN Internetworks," http://www.cisco.com/univercd/cc/td/doc/cisintwk/idg4/nd2012.htm
[Clark 1988] D. Clark, " The Design Philosophy of the DARPA Internet Protocols, Proceedings of ACM SIGCOMM'88, (Stanford, CA), Aug. 1988, Vol. 18, No. 4, http://www.acm.org/sigcomm/ccr/archive/1995/jan95/ccr-9501-clark.html
[Cusumano 1998] M.A. Cusumano and D.B. Toffle, Competing on Internet Time: Lessons from Netscape and its Battle with Microsoft, Free Press, 1998
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References and Hyperlinks 5References and Hyperlinks 5
[Daigle 1991] J. N. Daigle, Queuing Theory for Telecommunications, Addison-Wesley, Reading, MA, 1991.
[DEC 1990] Digital Equipment Corporation, "In Memoriam: J. C. R. Licklider 1915-1990," SRC Research Report 61, Aug. 1990. http://gatekeeper.dec.com/pub/DEC/SRC/research-reports/abstracts/src-rr-061.html
[Dertouzos 1999] M. Dertouzos, "The Future of Computing," Scientific American, August 1999, pp.52-55.
[Fraser 1983] A. G. Fraser, "Towards a Universal Data Transport System," IEEE Journal on Selected Areas in Communications, Vol. SAC-1, No 5, pp. 803-816.
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References and Hyperlinks 6References and Hyperlinks 6
[Fraser 1993] A. G. Fraser (1993). "Early Experiments with Asynchronous Time Division Networks," IEEE Network Magazine, Vol. 7, No. 1, pp. 12-27.
[Goodman 1997] D. Goodman (Chair), The Evolution of Untethered Communications, National Academy Press, Washington DC, Dec. 1997. http://www.nap.edu/readingroom/books/evolution/index.html
[Green 1992] P. Green, Fiber Optics Networks, Prentice Hall, 1992
[Greenberg 1997] I. Greenberg, "The Future of the Living Room." http://www.cnet.com/Content/Features/Dlife/Living/index.html
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References and Hyperlinks 7References and Hyperlinks 7
[Haynal 1999] R. Haynal, "Internet Backbones," http://navigators.com/isp.html
[Huston 1999a] G. Huston, "Interconnection, Peering, and Settlements - Part I," The Internet Protocol Journal, Vol. 2, No. 1, (June 1999). http://www.cisco.com/warp/public/759/ipj_2-1/ipj_2-1_ps1.html
[Huston 1999b] G. Huston, "Interconnecting, Peering, and Settlements - Part II," The Internet Protocol Journal, Vol. 2, No. 2 (June 1999). http://www.cisco.com/warp/public/759/ipj_2-2/ipj_2-2_ps1.html
[Iren 1999] S. Iren, P. Amer, P. Conrad, "The Transport Layer: Tutorial and Survey," ACM Computing Surveys, Vol 31, No 4, (Dec 1999). http://www.cis.udel.edu/~amer/PEL/survey/
[Jacobson 1988] V. Jacobson, "Congestion Avoidance and Control," Proceedings of ACM SIGCOMM '88, pp. (Stanford, CA, Aug. 1988), 314-329, ftp://ftp.ee.lbl.gov/papers/congavoid.ps.Z
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References and Hyperlinks 8References and Hyperlinks 8
[Kegel 1999] Dan Kegel's ISDN Page, http://alumni.caltech.edu/~dank/isdn/
[Kleinrock 1961] L. Kleinrock, "Information Flow in Large Communication Networks," RLE Quarterly Progress Report, July 1961.
[Kleinrock 1964] L. Kleinrock, 1964 Communication Nets: Stochastic Message Flow and Delay, McGraw-Hill, NY, NY, 1964.
[Kleinrock 1975] L. Kleinrock, Queuing Systems, Vol. 1, John Wiley, New York, 1975.
[Kleinrock 1976] L. Kleinrock, Queuing Systems, Vol. 2, John Wiley, New York, 1976.
[Kleinrock 1998] L. Kleinrock, "The Birth of the Internet," http://www.lk.cs.ucla.edu/LK/Inet/birth.html
[Leiner 1998] B. Leiner, V. Cerf, D. Clark, R. Kahn, L. Kleinrock, D. Lynch, J. Postel, L. Roberts, and S. Woolf, "A Brief History of the Internet," http://www.isoc.org/internet/history/brief.html
[List 1999] "The List: The Definitive ISP Buyer's Guide," http://thelist.internet.com/
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References and Hyperlinks 9References and Hyperlinks 9
[Lucky 1997] R. Lucky, "New Communication Services - What Do People Want?", Proceedings of the IEEE, Oct. 1997, pp 1536-1543.
[Metcalfe 1976] R. M. Metcalfe and D. R. Boggs. "Ethernet: Distributed Packet Switching for Local Computer Networks," Communications of the Association for Computing Machinery, Vol. 19, No. 7, (July 1976), pp. 395 - 404. http://www.acm.org/classics/apr96/
[Mills 1998] S. Mills, "TV set-tops set to take off," CNET News.com, Oct. 1998. http://news.cnet.com/news/0-1006-200-334433.html
[NAS 1995] National Academy of Sciences, The Unpredictable Certainty: Information Infrastructure Through 2000, National Academy of Sciences Press, 1995. http://www.nap.edu/readingroom/books/unpredictable/chap4.html
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References and Hyperlinks 10References and Hyperlinks 10
[Network 1996] Network Wizards, "Internet Domain Survey", July 1996, http://www.nw.com/zone/WWW-9607/report.html
[Network 1999] Network Wizards, "Internet Domain Survey," Jan. 1999, http://www.isc.org/ds/
[Pacific Bell 1998] Pacific Bell, "ISDN Users Guide," http://www.pacbell.com/Products_Services/Residential/ISDNuserguide/0,1078,20,00.html
[Perkins 1994] A. Perkins, "Networking with Bob Metcalfe," The Red Herring Magazine, Nov. 1994. http://www.herring.com/mag/issue15/bob.html
[Quittner 1998] J. Quittner, M. Slatalla, Speeding the Net: The Inside Story of Netscape and How it Challenged Microsoft, Atlantic Monthly Press, 1998.
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References and Hyperlinks 11References and Hyperlinks 11
[Ramaswami 1998] R. Ramaswami, K. Sivarajan, Optical Networks: A Practical Perspective, Morgan Kaufman Publishers, 1998
[RFC 001] S. Crocker, "Host Software," RFC 001 (the very first RFC!).
[RFC 793] J. Postel, "Transmission Control Protocol," RFC 793, Sept. 1981. http://www.rfc-editor.org/rfc/rfc793.txt
[RFC 801] J. Postel, "NCP/TCP Transition Plan," RFC 801 Nov. 1981. http://www.rfc-editor.org/rfc/rfc801.txt
[RFC 1034] P. V. Mockapetris, "Domain Names--Concepts and Facilities," RFC 1034, Nov. 1987. http://www.rfc-editor.org/rfc/rfc1034.txt
[Roberts 1967] L. Roberts, T. Merril, "Toward a Cooperative Network of Time-Shared Computers," AFIPS Fall Conference, Oct. 1966.
[Ross 1995] K. W. Ross, Multiservice Loss Models for Broadband Telecommunication Networks, Springer, Berlin, 1995.
[Segaller 1998] S. Segaller, Nerds 2.0.1, A Brief History of the Internet, TV Books, New York, 1998.
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[Thinplanet 2000] Thinplanet homepage, http://www.thinplanet.com/
[Turner 1986] J. Turner, "New Directions in Communications (or Which Way to the Information Age?)," Proceedings of the Zürich Seminar on Digital Communication, (Zurich, Switzerland, Mar. 1986), pp. 25-32,.
[W3C 1995] The World Wide Web Consortium, "A Little History of the World Wide Web," 1995. http://www.w3.org/History.html
[Wakeman 1992] Ian Wakeman, Jon Crowcroft, Zheng Wang, and Dejan Sirovica, "Layering Considered Harmful," IEEE Network, Jan. 1992, p. 20-24.
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[Waung 1998] W. Waung, "Wireless Mobile Data Networking The CDPD Approach," Wireless Data Forum, 1998. http://www2.wirelessdata.org/public/whatis/whatis.html
[Wireless 1998] Wireless Data Forum, "CDPD System Specification Release 1.1," 1998. http://www2.wirelessdata.org/public/specification/index.html
[Wood 1999] L. Wood, "Lloyds Satellites Constellations," http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/iridium.html
[Ziff-Davis 1998] Ziff-Davis Publishing, "Ted Nelson: Hypertext pioneer," 1998. http://www.zdnet.com/zdtv/screensavers_story/0,3656,2127396-2102293,00.html© 2000-2001 by Addison Wesley Longman A division of Pearson Education.