This document discusses IP addresses and subnetting. It begins by explaining that each network interface has a unique IP address. IP addresses are 32 bits long and contain a network and host portion, allowing for a two-level address hierarchy. The document then covers IP address classes and explains subnetting allows a single IP address to span multiple physical networks by using host ID bits as a subnet ID. Subnet masks allow hosts to determine if another IP is on the same subnet.

1. JIMS, Greater Noida
IP Addresses and Subnetting
Hirdesh Sharma,
Department of CSE
4/28/2023
1
Hirdesh Sharma RCA 402 Computer Network Unit: 1
Computer Network

2. • IP is connectionless datagram protocol and is an unreliable protocol because it does
not provide any error control & flow control mechanism.
• Packets in IP Layer are called datagram.
• Each interface on internet has a unique global address called IP address.
• Services provided by IP are: Addressing, Fragmentation, Packet Timeout, Type of
Service.
• IPv6 is the next generation protocol as the successor of IPv4.
• Host and Router has a unique IP Address on Internet.
• Classes of IP Address are: Class A, Class B, Class C, Class D, Class E.
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Prerequisite and Recap

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IP Addresses (CO3)
• Each network interface on the Internet as a unique global address, called the IP
address.
• An IP address- is 32 bits long. It encodes a network number and a host number.
• IP addresses are written in a dotted decimal notation.
Ex: 128.238.42.112

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IP Address Classes (CO3)
• Class A:
– For very large organizations
– 16 million hosts allowed
• Class B:
– For large organizations
– 65 thousand hosts allowed
• Class C
– For small organizations
– 255 hosts allowed
• Class D
– Multicast addresses
– No network/host hierarchy

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IP Address Hierarchy (CO3)
Internet= a collection of connected networks which share a common set of rules
for communication.
IPAddress Hierarchy
– Note that Class A, Class B, and Class C addresses only support two levels of
hierarchy
– Each address contains a network and a host portion, meaning two levels of
Hierarchy.
– However, the host portion can be further split into “subnets” by the address
class owner
– This allows for more than 2 levels of hierarchy.

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IP Subnetting (CO3)
• Subnetting is a technique used to allow a single IP network address to Span
multiple physical networks.
• IP hosts should support subnetting.
• Subnetting is done by using some of the bits of the host-id part of the IP address
physical layer network identifier.
• The subnet mask is used to determine the bits of the network identifier.
• All hosts on the same network should have the same subnet mask.
• IP address is composed of a Netid part and a Hostid part ⇒2-level hierarchy.
• Sometimes a 2-level hierarchy is insufficient for an organisation’s needs.

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IP Subnetting (CO3)

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Subnetting (CO3)
• An IP packet from some other network destined for host 141.14.2.21 still reaches
router R1, since the destination address is still a Class B address with Netid141.14
and Hostid 2.21 as far as the rest of the Internet is concerned.
• when the packet reaches router R1, the interpretation of the IP address changes
• R1 knows that there are 3 levels of hierarchy within the organization, and that in
this case, the Netid is 141.14,the Subnetid is 2, and the Hostid is 21.
• How is this knowledge of the internal network hierarchy implemented in the
organization’s routers?

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Subnetting (CO3)
• Masking of IP addresses during the packet-forwarding process.
• Masking is done whether or not subnetting is being used with subnetting, the Netid
defines the site, the Subnetid defines the physical network, and the Hostid defines
the actual machine.

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Subnet Masks (CO3)
• Subnet Masks: Subnet masks allow hosts to determine if another IP address is on
the same subnet or the same network.

11. Q:1 Explain IP Address. Discuss the various classes of IP Address.
Q:2 Define the concept of IP Subnetting with the help of suitable diagram.
Q:3 What are Subnet Masks.
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Weekly Assignment

12. Q:1 A 4 byte IP address consists of __________
a) only network address
b) only host address
c) network address & host address
d) network address & MAC address
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MCQ s

13. Q:1 Define the concept of IP Subnetting with the help of suitable diagram.
Q:2 What are Subnet Masks.
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Expected Questions for University Exam

14. • Each network interface on the Internet as a unique global address, called the IP
address.
• Each address contains a network and a host portion, meaning two levels of
Hierarchy.
• Subnetting is a technique used to allow a single IP network address to Span
multiple physical networks. IP hosts should support subnetting.
• Subnet masks allow hosts to determine if another IP address is on the same subnet
or the same network.
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Summery

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References
• Behrouz A. Forouzan, “Data communication and Networking”, Tata
McGraw– Hill,
• Larry L.Peterson, Peter S. Davie, “Computer Networks”, Elsevier, Fifth
Edition, 2012.
• William Stallings, “Data and Computer Communication”, Pearson Education,
• James F. Kurose, Keith W. Ross, “Computer Networking