Addressing the Network – IPv4 : Addressing the Network – IPv4 Network Fundamentals – Chapter 6
Objectives (Chapter 6 – B) : Objectives (Chapter 6 – B) Determine the network portion of the host address and explain the role of the subnet mask in dividing networks.
Apply VLSM to solve unequal subnet scenarios
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.
Practice - Reserved addresses : 3 IP Address –10.18.127.100
Subnet Mask –
Network address =
Broadcast address = Practice - Reserved addresses 255.0.0.0 10.0.0.0 10.255.255.255 The first question to ask is, ‘What class is this address?’ Class A
Practice - Reserved addresses : 4 IP Address –131.234.12.66
Subnet Mask –
Network address =
Broadcast address = Practice - Reserved addresses 255.255.0.0 131.234.0.0 131.234.255.255 What class is this address? Class B
Practice - Reserved addresses : 5 IP Address –199.218.4.56
Subnet Mask –
Network address =
Broadcast address = Practice - Reserved addresses 255.255.255.0 199.218.4.0 199.218.4.255 What class is this address? Class C
Practice - Reserved addresses : 6 IP Address – 210.189.137.100
Subnet Mask – 255.255.255.240
Network address = Practice - Reserved addresses 210.189.137.96 What class is this address? Class C
How ANDing Resolves the Network Address : How ANDing Resolves the Network Address It’s simple math! Convert address and mask to Binary and then multiply bit positions.
ANDing Continued… : ANDing Continued… Easy steps:
Convert Address and Mask to binary
Multiply bit position (only 1 x 1 will result in a positive)
Convert binary result to decimal
ANDing Worksheet : ANDing Worksheet Pause
Go Classless! Network in Host Bits : Go Classless! Network in Host Bits Classed networks (A,B,C) can “loan” host bits to create more networks
These “subnetworks” are defined by the subnet mask
Example below: Class B address borrows 8 bits to create 256 additional networks
Calculating Addresses : Calculating Addresses Changing the mask changes the network address
Provides more logical networks, but fewer host addresses
Subnetting Basics : 12 Subnetting Basics To create subnets, some host bits are reassigned, or borrowed as network bits
Always start borrowing with the leftmost host bit, the one closest to the last network bit
Subnetting provides
Addressing flexibility
Broadcast containment (smaller Broadcast domains)
Low level LAN security
Easy Subnet example : 13 Easy Subnet example Create 256 additional networks from this private address:
10.0.0.0
Black = network; red = sN; green = host
List classed address first: 00001010. 00000000. 00000000.00000000 00001010. 00000000. 00000000.00000000
Class C example : 14 Class C example Write out the binary for the following address, borrowing 3 bits for subnets:
192.168.10.0
Black = network; Red = sN; Green = host
Class address first 11000000.10101000.00001010.00000000 11000000.10101000.00001010.00000000
Subnet Mask : 15 Subnet Mask Class C = 255.255.255.0
If three bits were borrowed, the mask for a Class C address would be
11111111.11111111.11111111.11100000
The fourth octet, 224 = 11100000
Mask is written as: 255.255.255.224
My be written as: 199.55.84.203/27
How Many Bits to Borrow?? : 16 Calculate how many hosts the largest subnet requires
OR...
Calculate the number of subnets needed How Many Bits to Borrow??
How Many Subnets : 17 How Many Subnets Number of total subnets = two to the power of the borrowed bits
2 x power of borrowed bits
Borrow 3 bits: 23 = 8
Borrow 4 bits: 24 = 16
Borrow 5 bits: 25 = 32
Borrow 6 bits: 26 = 64
Borrow 7 bits: 27 = 128
Borrow 8 bits: 28 = 256
Note: under certain conditions N – 2 required
to determine useable subnets
How Many Hosts/Usable Hosts : 18 Number of hosts = two to the power of the bits remaining
Number of usable hosts minus two (reserved addresses for subnet network ID and subnet broadcast).
2 x power of remaining host bits - 2 = usable hosts
3 bits borrowed, leaves 25 = 32 - 2 = 30 hosts
4 bits borrowed, leaves 24 = 16 - 2 = 14 hosts
5 bits borrowed, leaves 23 = 8 - 2 = 6 hosts
6 bits borrowed, leaves 22 = 4 - 2 = 2 hosts
Host bits are the magic number
Harry Potter Subnetting How Many Hosts/Usable Hosts
Subnet Practice: Borrow 3 bits : 19 Subnet Practice: Borrow 3 bits 192.168.4.32 192.168.4.224 192.168.4.192 192.168.4.160 192.168.4.128 192.168.4.96 192.168.4.64 192.168.4.0 192.168.4.31 192.168.4.255 192.168.4.223 192.168.4.191 192.168.4.159 192.168.4.127 192.168.4.95 192.168.4.63 .1-.31 .225-.254 .193-.222 .161-.190 .129-.158 .97-.126 .65-.94 .33-.62 When in doubt, do the binary!
Dividing Networks into the Right Sizes : Dividing Networks into the Right Sizes Subnetting a subnet
Variable Length Subnet Mask (VLSM)
Subnets from a Subnetwork Block : Subnets from a Subnetwork Block Calculate the number of hosts in a network range given an address and subnet mask
Testing the Network Layer - PING : Testing the Network Layer - PING Ping is a primary testing tool for IP
ICMP echo request/reply at Layer 3 Loopback Address
Testing Across the Network : Testing Across the Network Test by PINGing from near to far
Host
Host on same subnet
Gateway
Host on different subnet
Host by domain name (DNS) Windows Firewall blocks Echo Replies by default
Testing the Network Layer – Next Hop : Testing the Network Layer – Next Hop Traceroute also uses ICMP echo request/request
Calculates Round Trip Time (RTT)
Uses Time To Live (TTL) field to measure hops Windows = tracert
Cisco IOS = traceroute
Testing the Network Layer - ICMP : Testing the Network Layer - ICMP Internet Control Messaging Protocol
Reports certain errors related to network events
Note: how does layer three handle delivery errors?
Examples:
Host confirmation (echo)
Unreachable destination/service
Time Exceeded
Route Redirection
Source Quench
Chapter 6 Labs – Part B : Chapter 6 Labs – Part B Activity 6.7.x: IPv4 Address Subnetting Part 1 & 2
Lab 6.7.2: Examining ICMP Packets
Lab 6.7.x: Subnet and Router Configuration
(Packet Tracer)
Slide 27 :