Transcript 6.5.2 Subnetting – Dividing Networks into Right Sizes

Addressing the Network – IPv4
Network Fundamentals – Chapter 6
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Objectives

Explain the structure IP addressing and demonstrate the ability
to convert between 8-bit binary and decimal numbers.

Given an IPv4 address, classify by type and describe how it is
used in the network

Explain how addresses are assigned to networks by ISPs and
within networks by administrators

Determine the network portion of the host address and explain
the role of the subnet mask in dividing networks.

Given IPv4 addressing information and design criteria, calculate
the appropriate addressing components.

Use common testing utilities to verify and test network
connectivity and operational status of the IP protocol stack on a
host.
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Course Index
 6.1 IPv4 Addresses
 6.2 Addresses for Different Purpose
 6.3 Assigning Addresses
 6.4 Is It On My Network?
 6.5 Calculating Addresses
 6.6 Testing the Network Layer
 6.7 Lab and Activities
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6.1 IPv4 Addresses
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6.1.1 The Anatomy of an IPv4 Address
 32bit
 Dotted Decimal
 Network and Host Portions
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6.1.2 Knowing the Number – Binary to Decimal Conversion
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6.1.4 Knowing the Number – Decimal to Binary Conversion
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6.2 Addresses for Different Purpose
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6.2.1 Types of Addresses in an IPv4 network
 Network address - The address by which we refer to the network. It is
the lowest address is reserved for the network address. (All host bits
is 0)
 Broadcast address - A special address used to send data to all hosts
in the network. It is the highest address in the network range. (All host
bits is 1)
 Host addresses - The addresses assigned to the end devices in the
network.
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6.2.2 Calculating Network, Hosts and
Broadcast Addresses
 Network Prefixes
Indicated by the Prefix Length
The number of bits in the address that gives us the network portion.
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6.2.2 Calculating Network, Hosts, and
Broadcast Addresses
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6.2.3 Unicast, Broadcast, Multicast – Types of
Communication
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Limited Local broadcast address
STOP
255.255.255.255
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Directed broadcast address
192.168.20.0
192.168.1.0
192.168.20.255
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6.2.4 Reserved IPv4 Address Range
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6.2.5 Public address and private address
 Public Addresses
 Private address
10.0.0.0 to 10.255.255.255 (10.0.0.0 /8)
172.16.0.0 to 172.31.255.255 (172.16.0.0 /12)
192.168.0.0 to 192.168.255.255 (192.168.0.0 /16)
 NAT
Practice 6.2.5
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6.2.6 Special IPv4 addresses
 Network and Broadcast Addresses
 Default Route:0.0.0.0
 Loopback:127.0.0.0/8
 Link-Local Addresses:169.254.0.0 /16
 TEST-NET Addresses:192.0.2.0 /24
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6.2.7 Legacy IPv4 addressing
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6.3 Assigning Addresses
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6.3.1 Planning to Addresses the Network
 It’s a structure process, should be planned and documented.
Preventing duplication of addresses
Providing and controlling access
Monitoring security and performance
 The different types of hosts within a network
hosts are associated with an IPv4 network by a common network
portion of the address
End devices for users
Servers and peripherals
Hosts that are accessible from the Internet
Intermediary devices
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6.3.1 Planning to Addresses the Network
 Planning to Addresses the Network Considerations
include:
Will there be more devices connected to the network than public
addresses allocated by the network's ISP?
Will the devices need to be accessed from outside the local network?
If devices that may be assigned private addresses require access to
the Internet, is the network capable of providing a Network Address
Translation (NAT) service?
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6.3.2 Static or Dynamic Addressing for End
User Devices
 Addresses for User Devices
Static Assignment of Addresses
Dynamic Assignment of Addresses
DHCP
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6.3.3 Assigning Addresses to Other devices
 Addresses for Servers and Peripherals
 Addresses for Hosts that are Accessible from Internet
 Addresses for Intermediary Devices
 Routers and Firewalls
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6.3.4 & 6.3.5 Who Assigns the Different
Addresses?
 The organization of address management
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6.3.6 Overview of IPv6
 IPv6 Features and Advantages
128-bit hierarchical addressing - to expand addressing
capabilities
Header format simplification - to improve packet handling
Improved support for extensions and options - for increased
scalability/longevity and improved packet handling
Flow labeling capability - as QoS mechanisms
Authentication and privacy capabilities - to integrate security
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6.4 Is It On My Network?
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6.4.1 The subnet mask - Defining the network
and host portions
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6.4.2 ANDing – What is in our network?
 When ANDing between the address and the subnet mask is performed, the
result yields the network address.
 Routers use ANDing to determine an acceptable route for an incoming packet.
 An originating host use ANDing to determine if a packet should be sent
directly to a host in the local network or be directed to the gateway.
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6.4.3 The ANDing Process
 An Exercise of ANDing
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6.5 Calculating Addresses
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6.5.1 Basic Subnetting
 Each interface on a router must have a unique network ID
 Create the subnets by using (borrow) one or more of the host bits
as network bits.
 Subnets number=2^n (n = the number of bits borrowed)
 Host number= 2^n - 2 (n=the number of bits left for hosts)
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6.5.1 Basic Subnetting
 Subnetting Example (4 networks)
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6.5.1 Basic Subnetting
 Subnetting Example (8 networks)
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6.5.2 Subnetting – Dividing Networks into Right Sizes
 Step 1 Determine the Total Number of Hosts
This includes end user devices, servers, intermediate devices,
and router interfaces.
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6.5.2 Subnetting – Dividing Networks into Right Sizes
 Step 2 Determine the Number and Size of the Networks
Consider the number of networks and the size of each required
based on common groupings of hosts.
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6.5.2 Subnetting – Dividing Networks into Right Sizes
 Step 3 Allocating Addresses
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6.5.2 Subnetting – Dividing Networks into Right Sizes
 Subnetting – Spreadsheet, a helpful tool
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6.5.3 Subnetting – Subnetting a Subnet
 Subnetting a subnet, or using Variable Length Subnet
Mask (VLSM) was designed to maximize addressing
efficiency
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6.5.3 Subnetting – Subnetting a Subnet
 VLSM Example
In the example, using a standard subnetting (/26 prefix length)
scheme would be wasteful.
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6.5.3 Subnetting – Subnetting a Subnet
 VLSM Example
Using VLSM
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6.5.3 Subnetting – Subnetting a Subnet
 VLSM Example
Using VLSM
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6.5.4 Determining the Network Address
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6.5.5 Determining the Number of hosts
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6.5.6 Determining Valid Addresses for Hosts
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6.6 Testing the Network Layer
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6.6.1 Ping 127.0.0.1 – Testing the Local Stack
 Ping
It is a utility for testing IP connectivity between hosts.
 Pinging the Local Loopback (127.0.0.1)
A response from 127.0.0.1 indicates that IP is properly installed
on the host.
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6.6.2 Ping gateway
 Testing connectivity to the local LAN
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6.6.3 Ping remote host
 Testing connectivity to remote LAN
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6.6.4 Traceroute (tracert) – Tesing the Path
 It takes advantage of Time to Live (TTL)
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6.6.5 ICMPv4 – The Protocol Supporting
Testing and Messaging
 Internet Control Messaging Protocol (ICMPv4)
ICMP is the messaging protocol for the TCP/IP suite
ICMP provides control and error messages
It is actually a separate Layer 3 protocol of the TCP/IP suite
ICMP messages that may be sent include:
Host conformation
Unreachable Destination or Service
Time exceeded
Route redirection
Source quench
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Summary
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