Download Module 2: Assigning IP Addresses in a Multiple Subnet

Module 2: Assigning IP
Addresses in a Multiple
Subnet Network
Overview
Assigning IP Addresses
Creating a Subnet
Using IP Routing Tables
Overcoming Limitations of the IP Addressing
Scheme
Lesson: Assigning IP Addresses
The Components of an IP Address
What Are the Classes of IP Addresses?
How Dotted Decimal Notation Relates to Binary Numbers
How to Convert Dotted Decimal Notation to Binary
Format
How Subnet Masks Work
Guidelines for IP Addressing
Multimedia: The Components of an IP Address
IP Address
192.168.2.180
IP Address
192.168.2.182
IP Address
192.168.1.180
IP Address
192.168.2.181
IP Address
192.168.1.181
IP Address
192.168.1.182
What Are the Classes of IP Addresses?
Class A
Large network
Network ID
Host ID
0
w
Class B
Medium network
y
Network ID
z
Host ID
10
w
Class C
Small network
x
x
y
Network ID
z
Host ID
110
w
x
y
z
Practice: Determining the Class of an IP Address
In this practice, you will determine the class
of an IP address
How Dotted Decimal Notation Relates to Binary
Numbers
8 Bit Octet
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
27
26
25
24
23
22
21
20
128 64
32
16
8
4
2
1
Decimal Value
How to Convert Dotted Decimal Notation to Binary
Format
Your instructor will demonstrate how to convert an IP
address from dotted decimal notation to binary format
Practice: Converting Numbers Between Decimal and
Binary
In this practice, you will convert dotted
decimal notation to binary format and then
convert the binary number to dotted decimal
notation
Multimedia: How Subnet Masks Work
192.168.2.181
Subnet masks distinguish the host ID from
the network ID in an IP address by using:
1 bits to indicate the network ID
0 bits to indicate the host ID
Practice: Identifying the Components of an IP Address
In this practice, you will identify the
components of an IP address
Guidelines for IP Addressing
When assigning network and host IDs:
Do not use 127 for a network ID
Use public registered addresses only where
essential
Use IANA private address range for private
addresses
Do not use all binary 1’s for the host ID in a class-based
network
Do not use all binary 0’s for the network ID in a classbased network
Do not duplicate Host IDs
Practice: Identifying Invalid IP Addresses
In this practice, you will identify which IP
addresses are invalid
Lesson: Creating a Subnet
What Is a Subnet?
How Bits Are Used in a Subnet Mask
How to Calculate the Subnet Mask
Defining Subnet IDs
What Is a Subnet?
131.107.3.27
131.107.12.7
Subnet 2
131.107.3.0
Main network
131.107.12.0
131.107.10.12
Router
Subnet 1
131.107.10.0
131.107.12.31
Router
How Bits Are Used in a Subnet Mask
Class B Address With Subnet
Number of Subnets
Network ID
32
254
128
64
16
4028
Subnet ID
1 0
Number of Hosts
65,534
32,512
16,256
4,064
8,128
508
2,032
1,016
254
Host ID
How to Calculate the Subnet Mask
Your instructor will demonstrate how to calculate the
subnet mask
Defining Subnet IDs
1
255
255
224
0
11111111 11111111 11100000 00000000
Eight networks
are possible
1. 00000000 = 0
2. 00100000 = 32
3. 01000000 = 64
4. 01100000 = 96
5. 10000000 = 128
6. 10100000 = 160
7. 11000000 = 192
8. 11100000 = 224
2
Practice: Calculating a Subnet Mask
In this practice, you will calculate a subnet
mask for a given scenario
Lesson: Using IP Routing Tables
What Is a Router?
Using a Default Gateway
The Role of Routing in the Network Infrastructure
How the Computer Determines Whether an IP Address is
a Local or Remote Address
What Is Static and Dynamic Routing?
How the IP Protocol Selects a Route
How IP Uses the Routing Table
Using the Routing Table in Windows Server 2003
What Is a Router?
Communication path A-C-D
A
C
B
Routers
D
Communication path A-B-D
Using a Default Gateway
When you use a default gateway:
The default gateway:
 Routes packets to other networks
 Is used when the internal routing table on the host has
no information on the destination subnet
DHCP automatically delivers the IP address for the
default gateway to the client
To configure the client manually for the default
gateway, use the General tab on the Network
Connections Properties page
Multimedia: The Role of Routing in the Network
Infrastructure
Subnet 1
Router A
Subnet 2
Router B
Subnet 3
How the Computer Determines Whether an IP Address Is
a Local or Remote Address
Local and destination hosts’ IP addresses are each ANDed
with their subnet masks
 1 AND 1 = 1
 Other combinations = 0
 If ANDed results of source and destination hosts match,
the destination is local
10011111
IP address
Subnet mask 11111111
Result
10011111
11100000
11111111
00000111 10000001
00000000 00000000
11100000
00000000
00000000
Practice: Determining Whether an IP Address is a Local
or Remote Address
In this practice, you will determine whether a
given IP address is a local or remote address
What Is Static and Dynamic Routing?
Static routers:
Do not discover the IDs of remote networks
Do not exchange information with other routers
Are not fault tolerant
Dynamic routers:
Discover the IDs of remote networks
Exchange information with other routers
Can be fault tolerant
How the IP Protocol Selects a Route
Locates host address
matching destination
address?
Searches routing table for
destination address
IP creates packet
Yes
No
Locates network address
matching destination
address?
Transmits packet to the
designated gateway
?
No
Yes
Transmits packet to the
designated gateway
Yes
Transmits packet to the
designated gateway
?
Locates a default
gateway address?
No
Generates an error message
?
How IP Uses the Routing Table
Using the Routing Table in Windows Server 2003
Use the routing table to:
Check the accuracy of routing information
Determine the forwarding IP address
View the routing table by:
Typing route print at the command prompt, or
Using the netstat –r command
Practice: Viewing and Modifying a Routing Table
In this practice, you will view and then
modify an IP routing table
Lesson: Overcoming Limitations of the IP Addressing
Scheme
How IP Addresses Are Wasted
What Are Private and Public IP Addresses?
What Is VLSM?
How to Use VLSM
What Is Supernetting?
Using CIDR to Implement Supernetting
Multimedia: How IP Addresses Are Wasted
Limitations of the IP address scheme
can cause IP addresses to be wasted
Three ways to conserve IP addresses
Create private networks
Create supernets
Use variable length subnet masks
IP version 6 will resolve the limitations
What Are Private and Public IP Addresses?
Private addresses:
Do not have to be registered
Can be assigned by the network administrator
Are used on computers that are not accessed by the
Internet
Public addresses:
Are assigned by an ISP
Consist of unique class-based blocks
Are kept to a limited number
What Is VLSM?
Using VLSM, you can:
Create different sized subnets to match the number
of hosts in each subnet
Significantly reduce the number of unused IP
addresses
For example:
If you used a fixed length class C subnet mask
(255.255.255.0), you would have allocated 1778
addresses but used only 348, thereby wasting 1430.
Using VLSM you can reduce the number of unused
addresses to 133.
How to Use VLSM
Your instructor will demonstrate how to reduce the
number of IP addresses by using VLSM
What Is Supernetting?
Routing table before supernetting
220.78.168.0
220.78.169.0
220.78.170.0
220.78.171.0
220.78.172.0
220.78.173.0
220.78.174.0
220.78.175.0
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
255.255.255.0
220.78.168.1
220.78.168.1
220.78.168.1
220.78.168.1
220.78.168.1
220.78.168.1
220.78.168.1
220.78.168.1
Router
Routing table after supernetting
220.78.168.0
255.255.248.0
220.78.168.1
Using CIDR to Implement Supernetting
Class C Example
Network ID
Subnet mask (binary)
Starting
220.78.168.0 11011100 01001110 10101000 00000000
Ending
220.78.175.0 11011100 01001110 10101111 00000000
CIDR Entry
Network ID Subnet mask
220.78.168.0
Subnet mask (binary)
255.255.248.0 11111111 11111110 11111000 00000000