1. Computers need addresses to communicate with each other over the internet. There are four levels of addresses: physical, logical (IP), port, and specific. 2. The physical address, also called the MAC address, is a unique identifier for each network interface card. It allows packets to be delivered at the hardware level. The logical IP address allows universal communication across different physical networks. 3. The port address is a 16-bit label assigned to individual processes to enable communication between processes on the internet. Specific addresses like email addresses and URLs provide user-friendly labels.

1. Addressing
IP Addressing
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2. Addressing
• When the computers wish to communicate
with one another, they need to know the
address of each other. Each computer has its
own address.
• In an internet employing the TCP/IP protocols,
four levels of addresses are used by
computers :
1.Physical Address 2.Logical Address(IP)
3.Port Address 4.Specific Address
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3. 1.MAC Address(Physical Address)
• The packet from source to destination hosts pass through physical
address. At the physical level the IP address is not useful but the hosts and
routers are recognized by their MAC addresses.
• A MAC address is a local address. It is unique locally but it is not unique
universally.
• The IP and MAC address are two different identifiers and both of them are
needed, because a physical network can have two different protocol at the
network layer at the same time.
• Similarly a packet may pass through different physical networks.
• The size and format of the physical address varies depending on the
nature of network.
• The Ethernet(LAN) uses a 48-bit (6-byte) physical address which is
imprinted on the network interfacing card (NIC)
• The example of 48-bit or 6-byte physical address is as follows. It contains
12-hexadecimal digits.
08:63:4C:81:08:1D
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4. 2.Logical Addresses(IP Addresses)
• Logical addresses are required to facilitate
universal communication in which different type
of physical network can be involved.
• The logical address is also called as the IP
(Internet Protocol) address.
• At the network level, the hosts and routers are
recognized by their IP addresses or logical
addresses.
• The logical address used in internet is currently
32-bit address. The same IP address can never
used by more than one computer on the internet.
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5. 3.Port Address
• The main objective of internet is the process
communication. For this purpose it is necessary to label or
name the processes.
• Thus the processes need address. The label assigned to a
process is called as a port address. It is a 16-bit address.
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4. Specific Address
• Some applications have user friendly
addresses. The example of specific addresses
are the e-mail addresses or the GOOGLE
Resource Locators (URL)