ADVANCED NETWORKING
Unit:1
Topics: Classful Internet Addresses
MSc. CA&IT
Faculty: Pruthvirajsinh Parmar

UNIVERSAL IDENTIFIERS
 Universal Communication Service
 Host identifiers are classified as
o Name - What
o Address - Where
o Route - How

IP ADDRESS
 Each host on aTCP/IP internet is assigned a unique 32-bit internet address that
is used in all communication with that host.
 Pair of [ netID, hostID ]

NETWORK CONNECTION
 IP address does not specify individual computer, but a connection to the
network.
 Multi-homed host & Multiple IP Addresses

DOTTED DECIMAL NOTATION

ORIGINAL CLASSFUL ADDRESSING SCHEME
 Address is Self-Identifying
 Distinguished by first three bits

ORIGINAL CLASSFUL ADDRESSING SCHEME
 Class A : 7 bits to netid, 24 bits to hostid
 Class B : 14 bits to netid, 16 bits to hostid
 Class C : 21 bits to netid, 8 bits to hostid
 Class D : Used for multicasting
 Class E : reserved for future

CLASS RANGE
 Class A Address: 1-126 | more than 65536 host
 Class B Address: 128-191 | between 256 to 65534 hosts
 Class C Address: 192-223 | less than 254 hosts
 Class D Address: 224-239
 Class E Address: 240-254

NETWORK ADDRESS
 An address that has all bits of the hostID equal to 0 is reserved to refer to the
network.
 eg. 130.5.0.0

DIRECTED BROADCAST
 Any address with all bits of hostID equal to 1 is reserved for directed broadcast.
 eg. 130.5.255.255
 Sender can transmit a single packet that will be broadcasted on the specified
network.

LOCAL / LIMITED BROADCAST
 IP Address : all 1
 i.e. netID and hostID all 1
 i.e. 255.255.255.255
 A host may use the limited broadcast address as part of a start-up procedure
before it learns its IP address or the IP address prefix for the local network.

ALL-0s SOURCE ADDRESS
 IP Address : all 0
 i.e. netID and hostID all 0
 i.e. 0.0.0.0 (non-routable address)
 This address is used as a temporary source address at startup before a host
learns its IP address.

LOOPBACK ADDRESS
 The network prefix 127.0.0.0/8, a value from the class A range, is reserved for
loopback.
 eg. 127.0.0.1
 It is intended for use in testingTCP/IP and for inter-process communication on
the local computer.
 The computer processes the data without sending traffic across any network.

SPECIAL ADDRESS CONVENTIONS

IP MULTICAST
 Unicast : packet is delivered to one host
 Broadcast: packet is delivered to all hosts
 Multicast: packets is delivered to specific subnet of hosts

WEAKNESS IN INTERNET ADDRESSING
 If a host computer moves from one network to another, its IP address must
change.
 When network grows, it must move to higher class. Changing network addresses
can be incredibly time-consuming and difficult to debug.
 And vice-versa.

WEAKNESS IN INTERNET ADDRESSING
 Because routing uses the network portion of the IP address, the path taken by
packets traveling to a host with multiple IP addresses depends on the address
used.

NETWORK BYTE ODER
 Not all architectures store 32-bit integers in the same way.
 Two ways to store the data
o Big Endian
o Little Endian

NETWORK BYTE ODER
 Integer: 64536
 Binary: 11111100 00011000
o Most Significant Byte Least Significant Byte
o StartAddress+1 StartAddress
 Big Endian stores Msbyte first
 Little Endian stores Msbyte last
 Big Endian is generally used.

NETWORK MASK
 Helps you identify network and host
 Put all 1 in place of netID and all 0 in place of hostID
 Class A : 255.0.0.0
 Class B : 255.255.0.0
 Class C : 255.255.255.0

SUBNET AND CLASSLESS EXTENSIONS
 Limitation of
Classful
Addressing
Scheme

SUBNET AND CLASSLESS EXTENSIONS
 Classless network: 204.17.5.0/27
 i.e. 27 bits for network & 5 bits for host
 In last octet
 Using 3 bits we can create 8 subnets
 Using 5 bits we can have 32 host addresses (30 of which can actually be assigned)

SUBNET AND CLASSLESS EXTENSIONS
 204.17.5.0 255.255.255.224 assign host address range 1 to 30
 204.17.5.32 255.255.255.224 assign host address range 33 to 62
 204.17.5.64 255.255.255.224 assign host address range 65 to 94
 204.17.5.96 255.255.255.224 assign host address range 97 to 126
 204.17.5.128 255.255.255.224 assign host address range 129 to 158
 204.17.5.160 255.255.255.224 assign host address range 161 to 190
 204.17.5.192 255.255.255.224 assign host address range 193 to 222
 204.17.5.224 255.255.255.224 assign host address range 225 to 254

SUBNET AND CLASSLESS EXTENSIONS
 https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-
rip/13788-3.html
 https://pediaa.com/what-is-the-difference-between-classful-and-classless-
addressing/

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