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Microcomputer Networking II
TCP/IP addressing
•Addressing basics
• Address classes
• Address administration
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Microcomputer Networking II
IP addressing
• Each network interface in TCP/IP network is
assigned a unique 32-bit internet address that is
used in all communications with that host - IP
address
• IP Address encodes both host and network
numbers
• Host and address numbers depend on address class
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Microcomputer Networking II
IP addressing
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Class A - up to 126 networks with 16777214 hosts each
Class B - up to 16,382 networks with 65534 hosts each
Class C - up to 2097152 networks with 254 hosts each
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Figure from book Computer Networks 3rd ed., by A.S.
Tanenbaum
Microcomputer Networking II
IP addressing
• External representation - dotted decimal notation:
199.17.25.8 - each of the four bytes is written in
decimal
• Subnets
• Subnet mask splits address into network and host
numbers
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Figure from book Computer Networks 3rd ed., by A.S.
Tanenbaum
Microcomputer Networking II
IP addressing
• An address which has all bits of the hostid equal to
0 is used to refer to the network
• An address which has all bits of the hostid equal to
1 is broadcast address - directed broadcast
• If address contains all 32 1s, it is used for limited
broadcast
• All-zero address means “this host”
• All-zero network id means “this network”
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Microcomputer Networking II
Special IP Addresses
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Figure from book Computer Networks 3rd ed., by A.S.
Tanenbaum
Microcomputer Networking II
Weaknesses of IP addressing
• If a host computer moves from one network to
another, its IP address must be changed
• Inflexible address space
• Delivery of packets to host with multiple
interfaces depends on address used
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Microcomputer Networking II
Internet Address Administration
• Internet addresses are managed centrally:
– Internet Assigned Numbers Authority
http://www.iana.org
– Regional authorities:
• APNIC (Asia-Pacific Network Information Center)
http://www.apnic.net
• ARIN (American Registry for Internet Numbers )
http://www.arin.net
• RIPE NCC (Reseau IP Europeens) http://www.ripe.net
• Internal IP address space:
– 192.168.0.0
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Microcomputer Networking II
IP addressing example
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Figure from book Computer Networks and Internets., by D.
Comer
Microcomputer Networking II
Routing example
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas
Figure from book Computer Networks and Internets., by D.
Comer
Microcomputer Networking II
Network Byte Order
• Standard representation of data, independent of
hardware platform
• TCP/IP protocols define network standard byte
order
• Each router or host converts binary items to/from
local representation from/to network standard byte
order format
• Integers are sent most significant byte first (Big
Endian style)
St. Cloud State University
MCS 426, Fall 1999 Instructor: Adomas Svirskas