5. Twisted Pair
• Low cost
• easy to work with
• installed infrastructure
• crosstalk
• 300bps to 100Mbps
• “This modem is 56Kbps capable. However, current
regulations limit download speeds to 53Kbps,” the fine
print from a typical modem advertisement.
6. DSL
• Uses existing twisted pair
• 256Kbps to 40Mbps
• Loop length max about 18,000 ft.
• More correctly ADSL (Asymmetric Digital
Subscriber Line) with download speeds
different from upload speeds.
7. Coaxial Cable
• More expensive
• harder to work with
• not as extensive an existing infrastructure
– cable TV companies are changing this
• 56Kbps to 550Mbps
8. Fiber Optics
• Very expensive
• difficult to work with
• existing infrastructure limit to backbones
• 500Kbps to 30Gbps
9. Microwave
• Not as expensive as land lines
• Limited to line of site, (towers)
– reasonable infrastructure
• Satellite bounce, increases expense
– geo-synchronous (22,000 miles)
– low earth orbit (cheaper, lower power)
• 256Kbps to 100Mbps
10. Newer Wireless
– Cellular
– mobile data networks
– personal communications services (PCS)
– note: pagers & PDAs are not channels, they
would be nodes on one end of a channel
11. Transmission Speed
• BPS, bits-per-second, the amount of
information that can be transmitted through
a channel
• BAUD - a binary event, a signal change
from positive to negative or vice versa.
12. Speed II
• At higher speeds a single signal change can
transmit more than one bit at a time, so the
bit rate will generally be higher that the
baud rate.
• Transmission capacity is a function of the
frequency, higher frequency means higher
capacity
13. More Speed
• Bandwidth = range of frequencies that a
channel can support (difference between
highest and lowest frequency).
• Greater range means greater bandwidth.
• Greater bandwidth means greater
transmission capacity.
14. Faster Yet
• Bandwidth is like pipe diameter.
• Larger diameter pipes can transmit more
water in a given period of time.
• Personal Communication Services, PCSs,
have a greater bandwidth than fiber optics.
17. Networks
• Local Area Network, LAN
• Wide Area Network, WAN
• Value Added Network, VAN
18. Network Terms
• File server
• Print server
• Gateway - connects dissimilar networks
• Bridge - connects similar networks
• Routers - connects networks & directs traffic
• Similar networks = same network protocols
19. 20
Chapter 8
Transmission on LANs
• Token Ring
– can talk only when you have the token
– cost more than Ethernet
– better for high volume traffic
• Ethernet
– talk whenever you want
– send again if collision
– works best with low volume traffic
20. Transmission on WANs & VANs
• Packet Switching
– message broken into packets
– packets may take various routes
– message reassembled at destination
– allows load balancing on channels
• Frame Relay
– like packet switching, no error correction
21. The Internet
• What is the Internet?
• Who owns the Internet?
• Why does the Internet exist?
22. Evolution of the Internet
• 1970 ARPANET - 15 nodes
• 1972 first email
• 1982 TCP/IP becomes internet standard
– Transmission Control Protocol/Internet Protocol
• 1984 ARPANET - 1,000 nodes
• 1986 NSF-Net backbone on ARPANET
• 1987 ARPANET - 10,000 nodes
23. Evolution of the Internet
• 1988 - businesses begin to connect to
system for research purposes
• 1989 ARPANET - 100,000 nodes
• 1989 link email between CompuServe and
ARPANET
• 1990 ARPANET becomes the Internet
24. Public Networks
CompuServe
• 1969 started in Cleveland with single
computer
• 1979 provided first email
• 1980 started national service
• Mid-1980s largest online service
• 1995 3 Million users
• 1997 purchased by AOL
25. Public Networks
Prodigy
• 1986 pilot in Atlanta, Hartford, San
Francisco
• 1988 national service launched
• 1994 1st to offer WWW access
• 1999 Prodigy Classic discontinued (209,000
members)
26. Public Networks
AOL
• 1991 AOL for DOS
• 1993 AOL for Windows
• 1997 bought CompuServe
• 1999 10 Million users
• Estimated to have distributed over 1 Billion
discs of over 1,000 different disk/CD styles
28. The Keys to Internet Growth
• 1991 WAIS and Gopher provide Internet
search and navigation
• 1992 WWW hyperlink software released
• 1992 NSF relaxes its restriction on
commercial Internet traffic
• 1992+ explosive growth in usage
30. World Wide Web
• Set of standards for storing, retrieving,
formatting, and displaying information
using a client/server architecture
• Hypertext markup Language (HTML)
• browser
• search engines
31. Putting It All Together
AT&T Level 3
Centurylink
I29 Cable One
Consumer Consumer Consumer
32. Some Upper Tier Providers
• AT&T
• Bell Atlantic
• Bell South
• Cable and Wireless
• Cable One
• GTE
• IBM
• MCI
• Pacific Bell
• QUEST
• Sprint
• US West
33. Tier 1 Networks
• The largest backbones on the Internet:
• Centurylink, Telecom Italia, Verizon, Sprint,
TeliaSonera International, NTT Communications,
Deutsche Telekom, Level 3, AT&T
• These top branded backbones only trade peering
traffic among themselves.
34. Common Bandwidths
• 56K modem 0.056 Mbps
• ADSL 40 Mbps
• Cable Modem 50 Mbps
• T1 1.5 Mbps
• Ethernet 10 to 1,000 Mbps
• T3 44.7 Mbps
• See http://bandwidthplace.com/
36. Organization Benefits of Internet
• Reducing Communication Costs
– virtual private net
• Enhancing Communication and Coordination
• Accelerating the Distribution of Knowledge
• Facilitating Electronic Commerce
37. Intranets
• An internal network based on World Wide
Web technology
• Firewall
– security software to prevent unauthorized
access to an intranet
• Firebreak
– a physical break between the Internet and
Intranet
39. IP Addresses
• An identifier for a computer or device on a
TCP/IP network. Networks using the
TCP/IP protocol route messages based on
the IP address of the destination. The format
of an IP address is a 32-bit numeric address
written as four numbers separated by
periods. Each number can be zero to 255.
For example, 1.160.10.240 could be an IP
address.
40. IP Address Classes
• Class A - 168.212.226.204
• supports 16 million hosts on each of 127 networks
• Class B - 168.212.226.204
• supports 65,000 hosts on each of 16,000 networks
– NDUS has two Class B addresses
• 134.129.xxx.xxx Eastern ND
• 134.234.xxx.xxx Western ND
• Class C - 168.212.226.204
• supports 254 hosts on each of 2 million networks
41. IPv4 vs. IPv6
• IPv4
– 32 bits used for address
– 4,294,967,296
– Addresses not assigned by geographic region (see map)
• IPv6
– 128 bits used for address
– 340,282,366,920,938,463,374,607,431,768,211,456
– That about 3.7x10^21 addresses per square inch of the earth’s surface
– Addresses will be assigned by geographic region
42. IPv4 vs. IPv6
• IPv4 addresses written as four octets (8 bits)
separated by periods.
– 134.129.67.235
• IPv6 address written as eight 4-digit (16-bit)
hexadecimal numbers separated by colons.
– 1080:0:0:0:0:800:0:417A
43. Uniform Resource Locator
• http://www.ndsu.nodak.edu/ndsu/latimer/index.html#events
• http:// communication protocol
• www.ndsu.nodak.edu web server hosting the page
• /ndsu/latimer/ path to the page on the host server
• index.html filename of the page
• #events anchor in the page
44. IP & Domain Name Examples
• IP: 134.129.67.85
• URL: gdc.busad.ndsu.nodak.edu
• IP: 134.129.67.235
• URL: dyn235.minard-67.ndsu.nodak.edu
45. ICANN
• Internet Corporation for Assigned Names and Numbers
• a private sector, nonprofit organization
• responsibility for IP address space allocation, protocol
parameter assignment, domain name system management
and root server system management functions previously
performed under U.S. Government contract
• ICANN's diverse board consists of nineteen Directors, nine
At-Large Directors, who serve one-year terms and will be
succeeded by At-Large Directors elected by an at-large
membership organization. None of the present interim
directors may sit on the board once the permanent members
are selected.
46. IP Address Registries
• Regional Internet Registries:
• American Registry for Internet Numbers, ARIN
• Réseaux IP Européens Network Coordination
Centre, RIPE NCC
• Asia Pacific Network Information Centre, APNIC
• Latin American and Caribbean Internet Addresses
Registry, LACNIC
48. New Top-Level Domain Names
(TLDs)
• ICANN is accepting applications for new TLDs.
– Application window Jan. 12, 2012 to Apr. 12, 2012
– Application fee: $185,000
– Annual fee: $25,000
• Intent is to move towards more descriptive names
• Companies (organizations) can create
– Brand domains e.g. .pepsi .coke
– Generic domains e.g. .car .green
• http://mashable.com/2011/06/20/icann-top-level-domains/
