CS 350Chapter-8

Example(1C): 192.168.10.0 with mask 255.255.255.128/25

•How many subnets does the chosen subnet mask produce?

•Because 128 is 1 bit on (10000000), 2^1 = 2

•How many valid hosts per subnet are available?

•We have 7 host bits (10000000), 2^7-2 = 126

•What are the valid subnets?

•256-128 = 128. So they are 0, 128

•What’s the broadcast address of each subnet?

•127, 255

•What are the valid hosts in each subnet?

192.168.10.0: 192.168.10.1~ 192.168.10.126

192.168.10.128: 192.168.10.129~ 192.168.10.254

Example(2C): 192.168.10.0 with mask 255.255.255.192/26

•How many subnets does the chosen subnet mask produce?

•Because 192 is 2 bit on (11000000), 2^2 = 4

•How many valid hosts per subnet are available?

•We have 6 host bits (11000000), 2^6-2 = 62

•What are the valid subnets?

•256-192 = 64. So they are 0, 64, 128, 192

•What’s the broadcast address of each subnet?

•63, 127, 191, 255

•What are the valid hosts in each subnet?

192.168.10.0: 192.168.10.1~ 192.168.10.62

192.168.10.64: 192.168.10.65~ 192.168.10.126

192.168.10.128: 192.168.10.129~ 192.168.10.190

192.168.10.192: 192.168.10.193~ 192.168.10.254

Example(1B): 172.16.0.0 with mask 255.255.128.0/17

•How many subnets does the chosen subnet mask produce?

•Because 128 is 1 bit on (10000000), 2^1 = 2

•How many valid hosts per subnet are available?

•We have 15 host bits 2^15-2 = 32,766

•What are the valid subnets?

•256-128 = 128. So they are 0.0, 128.0

•What’s the broadcast address of each subnet?

•127.255 , 255.255

•What are the valid hosts in each subnet?

172.16.0.0: 172.16.0.1~ 172.16.127.254

172.16.128.0 : 172.16.128.1~ 172.16.255.254

Question192.168.10.0 = Network

4 subnets: 6 hosts, 10 hosts, 12 hosts, and 25 hosts

2 routers: router1 connects subnet1 and 2, router2 connects subnet3 and 4

How to make the mask for each subnet?

Troubleshooting IP Addressing

1. Check IP stack -- c:\> ping 127.0.0.1

2. Check NIC -- c:\> ping 172.16.10.2

3. Check local network from NIC to the router -- c:\> ping 172.16.10.1

4. Check the IP communication between the local host to the remote server -- c:\> ping 172.16.20.2

Packet InterNet Groper (ping)

traceroute –unix or linux

tracert --windows

arp –a

ipconfig /all

NAT

Placement and operation of a NAT box.

Inside local IPAddress:Port

Inside Global IPAddress:Port

10.0.0.1 198.60.42.1210.0.0.2 198.60.42.1310.0.0.3 198.60.42.14

Inside local IPAddress:Port

Inside Global IPAddress:Port

10.0.0.1:1492

198.60.42.12:1492

10.0.0.2:1723

198.60.42.12:1723

10.0.0.3:1024

198.60.42.12:1024