Ip addressing & subnetting Chapter 5b

objectives Upon completion of this chapter, you should be able to: Configure IP addresses Identify & select valid IP addresses for networks Configure a DHCP server Configure a host to use DHCP for configuration Troubleshoot & resolve IP addresses configuration and communication issues Configure DNS addresses Configure an IPv6 address

5.1.3 Classful subnetting

Parts of the Network Network Hosts Subnetwork

Subnetting- Split Up the IP address Borrow bits from host portion to make new networks Ask yourself… How many networks do you need? How many hosts per network are there? Instead of wasting a whole IP address range, you can split up an address & customize it for your network. In the picture: You have 4 networks & E1:4 hosts; E0 on A: 3 hosts; S0 to S1: 2 hosts; B’s E0: 3 hosts Think about expansion too.

Remember 2 addresses you can’t use: Network & Broadcast Some rules first… You MUST borrow at least 2 bits or leave at least 2 bits Class C has 1 octet to borrow from Class B has 2 octets to borrow from Class A has 3 octets to borrow from Remember the powers of 2 22= 4 23= 8 24= 16 25= 32 26= 64 Remember 2 addresses you can’t use: Network & Broadcast

199.72.101.0 Ask how many networks do we need? 4 2 to the what power will get you 4? 2^2 but if you subtract 2, you’ll only have 2, so use 2^3=8 What class address? C…..use only 1 octet Mark off bits borrowed (looking for networks) Create new subnet mask Powers of 2 chart for borrowed (networks) and left over (hosts/net) Create ranges Remove 1st & last ranges

199.72.101.0 Total Range #3 Useable Range #2 Network ID 199.72.101.64 /27 Broadcast Address 199.72.101.95 /27 199.72.101.0-31 .32-.63 (.33-.62) .64-.95 (.65-.94) .96-.127 (.97-.126) .128-.159 (.129-.158) .160-.191 (.161- .190) .192-.223 (.191-.222) .224-.255 Make sure to explain network and broadcast for each sub network. SHOW all zeros in the host bits!

Assign Addresses Note that each router port is a sub-network! When two routers connect to each other, both ports MUST be in the same network.

Router…Action! A packet with a destination IP of 199.72.101.85 255.255.255.224 goes to a router It ANDs to come up with the NETWORK #

How to Work Backwards 221.17.125.46 /28 What class address? C: Only deal with the last octet! 255.255.255.240 11111111.11111111.11111111.11110000 How many bits borrowed? 4 24= 16 networks How many bits left over? 24= 16 hosts per sub-network

Work Backwards Based on the IP address & SM, identify… The network address The broadcast address How many bits were borrowed How many bits were left over Is the address valid

What’s Wrong? PC1 has an address of 199.15.1.40 /28. PC2 has an address of 199.15.1.50 /28. Both are connected to a switch but they cannot communicate. The switch is working normally as are the PC’s NICs and Ethernet cables. Are the hosts on the same network or separate? Different subnets.

Questions What’s the broadcast address for 201.78.90.0 /24? 201.78.90.255 Default SM, no subnetting Sam’s Beef Hut uses network 215.67.106.0 & 255.255.255.240 to create subnets. How many useable hosts can be created per network? 14

Questions Which class gives you the most hosts/network? Which class give you the most networks? C Public IP addresses must be __________.

5.1.5 Classless subnetting

Classless Subnetting Allows you to use part of the address for the network portion Called partial subnetting or VLSM CIDR allows this Helps reduce wasted addresses You can subnet for each unequal network Your address is 210.1.17.64 /26 Net A needs 37 hosts Net B needs 15 hosts Net C needs 100 hosts

CIDR Block for Router Reduce the amount of routing table entries, use router summarization Use the common bits to make ONE routing table address per port. This is also called supernetting. It reduces the amount of routing table entries (they use the same supernet; which is called router summarization). In the picture, supernetting will reduce entries in router A’s routing table.

Test on addressing & subnetting

Ip addressing & subnetting Chapter 5b 4-5 days including test