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Physical & Logical Address
COMP 315
MAC Address
• A media access control address (MAC address) is a unique identifier
assigned to network interfaces for communications on the physical
network segment.
• MAC addresses are used as a network address for most IEEE 802 network
technologies, including Ethernet. Logically, MAC addresses are used in the
media access control protocol sublayer of the OSI reference model.
• Short for Media Access Control address, a hardware address that uniquely
identifies each node of a network. In IEEE 802 networks, the Data Link
Control (DLC) layer of the OSI Reference Model is divided into two sublayers: the Logical Link Control (LLC) layer and the Media Access Control
(MAC) layer. The MAC layer interfaces directly with the network medium.
Consequently, each different type of network medium requires a different
MAC layer.
• On networks that do not conform to the IEEE 802 standards but do
conform to the OSI Reference Model, the node address is called the Data
Link Control (DLC) address.
MAC Address
• MAC addresses are most often assigned by
the manufacturer of a network interface
controller (NIC) and are stored in its hardware,
such as the card's read-only memory or some
other firmware mechanism.
• If assigned by the manufacturer, a MAC
address usually encodes the manufacturer's
registered identification number and may be
referred to as the burned-in address (BIA).
MAC Address
MAC addresses are formed according
to the rules of one of three numbering
name spaces managed by the Institute
of Electrical and Electronics Engineers
(IEEE): MAC-48, EUI-48, and EUI-64.
The IEEE claims trademarks on the
names EUI-48 and EUI-64, in which EUI
is an abbreviation for Extended Unique
Identifier.
MAC Address
• The standard (IEEE 802) format for printing MAC48 addresses in human-friendly form is six groups
of two hexadecimal digits, separated by hyphens
(-) or colons (:), in transmission order (e.g. 01-2345-67-89-ab or 01:23:45:67:89:ab ).
• This form is also commonly used for EUI-64.
Another convention used by networking
equipment uses three groups of four hexadecimal
digits separated by dots (.) (e.g. 0123.4567.89ab
), again in transmission order.
MAC Address
MAC Address
• The original IEEE 802 MAC address comes
from the original Xerox Ethernet addressing
scheme.
• This 48-bit address space contains potentially
248 or 281,474,976,710,656 possible MAC
addresses.
MAC Address
• The first three octets (in transmission order)
identify the organization that issued the
identifier and are known as the
Organizationally Unique Identifier (OUI ).
• The following three (MAC-48 and EUI-48) or
five (EUI-64) octets are assigned by that
organization in nearly any manner they
please, subject to the constraint of
uniqueness.
How to find the MAC Address
ipconfig command
Logical Address (IP Address)
• IP address is short for Internet Protocol (IP)
address.
• An IP address is 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
• 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.
• Within an isolated network, you can assign IP addresses at
random as long as each one is unique. However, connecting a
private network to the Internet requires using registered IP
addresses (called Internet addresses) to avoid duplicates.
• An IP address can be static or dynamic. A static IP address will
never change and it is a permanent Internet address. A
dynamic IP address is a temporary address that is assigned
each time a computer or device accesses the Internet.
The Format of an IP Address
• The four numbers in an IP address are used in different ways
to identify a particular network and a host on that network.
Four regional Internet registries -- ARIN, RIPE NCC, LACNIC
and APNIC-- assign Internet addresses from the following
three classes:
• Class A - supports 16 million hosts on each of 126 networks
Class B - supports 65,000 hosts on each of 16,000 networks
Class C - supports 254 hosts on each of 2 million networks
The Format of an IP Address
• The number of unassigned Internet addresses
is running out, so a new classless scheme
called CIDR is gradually replacing the system
based on classes A, B, and C and is tied to
adoption of IPv6.
• In IPv6 the IP address size is increased from 32
bits to 128 bits.
CIDR
• Short for Classless Inter-Domain Routing, an IP addressing
scheme that replaces the older system based on classes A, B,
and C. With CIDR, a single IP address can be used to designate
many unique IP addresses. A CIDR IP address looks like a
normal IP address except that it ends with a slash followed by
a number, called the IP network prefix. For example:
172.200.0.0/16
• The IP network prefix specifies how many addresses are
covered by the CIDR address, with lower numbers covering
more addresses. An IP network prefix of /12, for example, can
be used to address 1,048,576 former Class C addresses.
What is My IP Address?
• To view your IP address you can use the ipconfig (IPCONFIG)
command line tool. Ipconfig displays all current TCP/IP
network configuration values and refreshes Dynamic Host
Configuration Protocol (DHCP) and Domain Name System
(DNS) settings.
• To launch the command prompt from a Windows-based
computer click: Start > All Programs > Accessories > Command
Prompt. Type ipconfig and hit enter.
• You can also use Google search to find your IP address. Type
what is my IP address as a search query and Google will show
the IP address of the computer from which the query was
received as the top search result.
IPv4 Format
IPv6
• IPv6 (Internet Protocol Version 6) is also called
IPng (Internet Protocol next generation) and it
is the newest version of the Internet Protocol
(IP) reviewed in the IETF standards
committees to replace the current version of
IPv4 (Internet Protocol Version 4).
IPv6
• IPv6 is an Internet Protocol (IP) for packet-switched internetworking that
specifies the format of packets (also called datagrams) and the addressing
scheme across multiple IP networks. In comparing the two protocols IPv6
expands upon the addressing and routing capabilities of IPv4 in a number
of ways including:
–
–
–
–
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In IPv6 the IP address size is increased from 32 bits to 128 bits
IPv6 supports a greater number of addressable nodes
IPv6 provides more levels of addressing hierarchy
IPv6 offers simpler auto-configuration of addresses
Ipv6 also supports simplified header format
IPv6
• Increasing the IP address pool was a major
factor in the development of IPv6. The biggest
benefit of IPv6 is that it will replace the IPv4
32-bit address scheme with a much longer
128-bit address scheme.
• The IPv4 32-bit address scheme allows for a
total of 232 addresses while IPv6 allows for 2128
total addresses.
IPv6 Format
Historical classful network
architecture
Class
Leading
bits
Size of
network
number
bit field
Size of
rest
bit field
Number
of networks
Addresses
per
network
Start
address
End
address
A
0
8
24
128 (27)
16,777,216
(224)
0.0.0.0
127.255.2
55.255
B
10
16
16
16,384 (214)
65,536 (216)
128.0.0.0
191.255.2
55.255
C
110
24
8
2,097,152 (221)
256 (28)
192.0.0.0
223.255.2
55.255
IANA-reserved private IPv4
network ranges
The Internet Assigned Numbers Authority (IANA) manages the IP address
space allocations globally and delegates five regional Internet registries
(RIRs) to allocate IP address blocks to local Internet registries (Internet
service providers) and other entities.
Start
End
No. of addresses
24-bit block (/8 prefix, 1 × A)
10.0.0.0
10.255.255.255
16777216
20-bit block (/12 prefix, 16 ×
B)
172.16.0.0
172.31.255.255
1048576
16-bit block (/16 prefix, 256 ×
C)
192.168.0.0
192.168.255.255
65536
Any user may use any of the reserved blocks. Typically, a network
administrator will divide a block into subnets; for example, many home
routers automatically use a default address range of 192.168.0.0 through
192.168.0.255 (192.168.0.0/24).