Module 10: Routing Fundamentals and Subnets

1
Module 10 Routing Fundamentals and Subnets

• 10.2.9 Small Router Purchase
• Subnetting Example
• 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

2
Subnetting Exercise

• A company has a class C network IP address and
  needs to subnet so that each Ethernet segment has
  10 hosts. 70 hosts are currently needed.
• Use IP address 200.12.15.0
• The following topology has been determined.

3
(No Transcript)
4
Question

1. How many subnets are needed to create this
   structure?
2. How many bits do I need to borrow for subnetting?
3. How many bits are left for the host IDs?
4. What is the subnet mask?
5. What IP address can be allocated for the
   computers in segment 1 assuming, this has the
   lowest subnet value.
6. What is the broadcast address for this subnet?
7. Repeat for the other segments

5

• 12 Subnets are needed
• 1 per router interface (only 1 subnet needed
  between 2 directly connected router)

6

• If borrowing 2 bits 22 2 subnets available 2
• If borrowing 3 bits 23 2 subnets available 6
• If borrowing 5 bits 23 2 subnets available 14

7

• Class C addresses have 8 bits available for use
  as host Ids. Using 4 for subnetting leaves 4 bits
  for hosts.
• The number of hosts per subnet is-
• 28-2 -2 14 hosts per subnet
• More that is required (10 1 for router)

8

• The subnet mask in binary is
• 11111111.11111111.11111111.11110000
• Network portion Subnet Hosts
• This is 255.255.255.240 in dotted decimal notation

9

• The lowest subnet IP address start at
• 200 .12 . 15 .00010001
• Network ID Subnet Hosts
• 17

10

• The highest subnet IP address is
• 200 .12 . 15 .00011110
• Network ID Subnet Hosts
• 30

11

• The broadcast IP address for this subnet is
• 200 .12 . 15 .00011111
• Network ID Subnet Hosts
• 31