Module 10: Routing Fundamentals and Subnets Small Router Purchase Subnetting Example a Basic Subnetting b Subnetting a Class A Network c Subnetting a Class B Network d Subnetting a Class C Network

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 The following topology has been determined.

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

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

2.If borrowing 2 bits 2 2 – 2 subnets available = 2 If borrowing 3 bits 2 3 – 2 subnets available = 6 If borrowing 5 bits 2 3 – 2 subnets available = 14

3.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: = 14 hosts per subnet More that is required (10 +1 for router)

4.The subnet mask in binary is Network portion Subnet Hosts This is in dotted decimal notation

5.The lowest subnet IP address start at Network ID Subnet Hosts 17

5.The highest subnet IP address is Network ID Subnet Hosts 30

5.The broadcast IP address for this subnet is Network ID Subnet Hosts 31