Subnetting Basicsl

1
Chapter 3

• Subnetting Basicsl

2
Summary of the Three Classes of Networks
3
Subnetting

• Benefits
• Reduce Network Traffic
• Routers create Broadcast Domains
• Optimal Performance
• Simplified Management
• Capable of spanning long distances
• Subnets
• Allow you to break large networks into smaller
  ones
• Must take bits from the hostid part of the
  address
• Always take from the left most hostid bits

4
First Things First

• Determine the number of networks needed
• One for each subnetwork
• One for each WAN segment
• Determine the number of hosts required
• One for each TCP/IP host
• One for each Router interface
• Create the following
• A subnet mask for the entire network
• A subnet id for each network segment
• A range of host ids for each subnet segment

5
Subnet Masks
6
Subnetting Class C Addresses

• Class C address 8 host bits
• Subnetting
• 10000000 128
• 11000000 192
• 11100000 224
• 11110000 240
• 11111000 248
• 11111100 252
• 11111110 254
• Rules
• Cannot have only 1 bit for subnetting
• Subnets 128 254 are illegal
• Cisco allows 1 bit to be used for subnetting
• ip subnet-zero

7
The Binary Method using 2 bits
8
The Alternate Method

• 1. How many subnets does the subnet mask produce?
• 2x xnumber of bits for subnet
• 2. How many valid hosts per subnet? 2y
• ynumber of bits for host ids
• 3. What are the valid subnets?
• 256 subnet first subnetwork (block)
• add the block to subnetwork
• stop when subnet mask is reached
• 4. What is the broadcast address of each subnet?
• Next subnetwork 1
• 5. What are the valid hosts in each subnet?
• First Host Subnetwork 1
• Last Host Broadcast - 1

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
Subnetting Practice Examples

• Class C
• Page 108
• Class B
• Page 114
• Class A
• Page 120

13
Super Netting

• Using Network / Subnet bits
• Increase Number of hosts available

14
Variable Length Subnet Masks (VLSM)

• Previous examples have used 1 fixed length subnet
  mask for entire network
• Example 192.168.10.0/28
• 255.255.255.240
• How many hosts on each subnet?

15
(No Transcript)
16
(No Transcript)
17
VLSM

• Allows for a varying number of hosts on different
  subnet segments
• Uses different size subnet masks for different
  subnet segments
• Not Supported by RIP v1.0 or IGRP
• Classful routing
• RIP v2.0, OSPF, EIGRP support
• Classless routing

18
(No Transcript)
19
(No Transcript)
20
Trouble Shooting

• PING 127.0.0.1 (localhost)
• TCP/IP stack intalled properly
• PING host ip address
• Communicating with you NIC
• PING the gateway (ie the router)
• Physical connectivity
• PING Server ip address
• Network path
• PING Server FQDN
• DNS is working

21
Whats the Problem?
22
Whats the Problem?
23
Things to Know

• Calculating subnet mask, host addresses,
  broadcast address
• Understand the various block sizes
• VLSM
• Four diagnostic steps
• Find and Fixing IP address problems

24
(No Transcript)