Sem1 - Module 10 Routing Fundamentals and Subnets

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Sem1 - Module 10 Routing Fundamentals and
Subnets
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Network address

• Network address provide a convenient way to refer
  to all of the addresses on a particular network
  or subnetwork.
• Two hosts with differing network address require
  a device, typically a router, in order to
  communicate.
• An IP address that ends with binary 0s in all
  host bits is reserved for the network address.

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Broadcast address

• Broadcast goes to every host with a particular
  network ID number.
• An IP address that ends with binary 1s in all
  host bits is reserved for the directed broadcast
  address.
• An IP address with binary 1s in all network bits
  and host bits is reserved for the local broadcast
  address.

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Local broadcast address
255.255.255.255
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Directed broadcast address
192.168.20.255
Broadcast address
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Example 172.16.20.200

• 172.16.20.200 is Class
• B address
• Network portion
• 172.16
• Host portion
• 20.200
• Network address
• 172.16.0.0
• Broadcast address
• 172.16.255.255

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• What is the decimal and binary range of the first
  octet of class B IP addresses?
• Decimal 128 191
• Binary   10000000 10111111
• Which octet(s) represent the network portion of a
  class C IP address?
• The first three octets
• Which octet(s) represent the host portion of a
  class A IP address?
• The last three octets

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IP Addresses
Host IP Address Address Class Network Address Portion Host Address Portion Broadcast Address
216.14.55.137
123.1.1.15
150.127.221.244
194.125.35.199
175.12.239.244
C
216.14.55
137
216.14.55.255
A
123
1.1.15
123.255.255.255
B
150.127
221.244
150.127.255.255
C
194.125.35
199
194.125.35.255
B
175.12
239.244
175.12.255.255
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Valid IP Address?

• 150.100.255.255
• This is a Class B
• This is the Broadcast Address
• NO - not valid IP Address

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Valid IP Address?

• 175.100.255.185
• This is a Class B
• The Host Bits are not all 0s or 1s
• Yes - valid IP Address

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Valid IP Address?

• 195.234.253.0
• This is a Class C
• This is the Network Address
• NO - not valid IP Address

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Valid IP Address?

• 100.0.0.23
• This is a Class A
• The Host Bits are not all 0s or 1s
• Yes - valid IP Address

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Valid IP Address?

• 188.256.221.176
• This would be a Class B
• BUT the 2nd Octet is greater than 255
• NO - not valid IP Address

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Valid IP Address?

• 127.34.25.189
• This would be a Class A
• BUT is invalid since 127 cannot be used in the
  first Octet reserved for diagnostic testing
• NO - not valid IP Address

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Valid IP Address?

• 224.156.217.73
• This is a Class D network
• Class D is reserved for multicasting cannot be
  used as a commercial IP address
• NO - not valid IP Address

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SubNet Mask Notation
Class C 255.255.255.0 192.168.100.0 255.255.255.
0 192.168.100.0/24 (24 Bits in the Network
part) Class B 255.255.0.0 172.16.0.0 255.255.
0.0 172.16.0.0/16 (16 Bits in the Network
part) Class A 255.0.0.0 10.0.0.0 255.0.0.0
10.0.0.0/8 (8 Bits in the Network part)
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SubNet Mask Notation
Not Valid for Class C (MUST borrow at least 2
Bits)
The last two bits in the last octet, regardless
of the IP address class, may never be assigned to
the subnetwork. These bits are referred to as
the last two significant bits.
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Host Subnet Schemes
The number of lost IP addresses with a Class C
network depends on the number of bits borrowed
for subnetting.
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SubNet Mask Notation
Consider Network 192.168.23.0/24 Subnet with a
SNM 255.255.255.224 3 Bits Borrowed ? /27
Fourth Octet
Position Value 128 64 32 16 8 4 2 1
Bit
1
1
1
0
0
0
0
0
SubNet Bits
Host Bits
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SubNet Mask Notation
Network 192.168.23.0/27 ? SNM 255.255.255.224
SubNet ID Host Range Start Host Range End Broadcast
0
1
2
3
4
5
6
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192.168.23.0
192.168.23.1
192.168.23.30
192.168.23.31
192.168.23.32
192.168.23.33
192.168.23.62
192.168.23.63
192.168.23.64
192.168.23.65
192.168.23.94
192.168.23.95
192.168.23.96
192.168.23.97
192.168.23.126
192.168.23.127
192.168.23.128
192.168.23.129
192.168.23.158
192.168.23.159
192.168.23.160
192.168.23.161
192.168.23.190
192.168.23.191
192.168.23.192
192.168.23.193
192.168.23.222
192.168.23.223
192.168.23.224
192.168.23.225
192.168.23.254
192.168.23.255
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Review

• Classes of IP address and range of IP on each
  class.
• Determine network portion and host portion in a
  IP address.
• Understand about broadcast addresses.
• Understand about valid host address.
• Binary and Decimal conversion.
• Subnetting

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Chapter 10

• Labs
• 10.3.5a (Basic Subnetting)
• 10.3.5b (Subnetting a Class A Network)
• 10.3.5c (Subnetting a Class B Network)
• 10.3.5d (Subnetting a Class C Network)
• 10.2.9 (Small Router Purchase) Homework
• See Web Page for Extra Practice