CS 350
Chapter-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:
192.168.10.192:
192.168.10.129~ 192.168.10.190
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
Question
192.168.10.0 = 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
Inside local IP
Address:Port
Inside Global IP
Address:Port
10.0.0.1
198.60.42.12
10.0.0.2
198.60.42.13
10.0.0.3
198.60.42.14
NAT
Inside local IP
Address:Port
Inside Global IP
Address: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
Placement and operation of a NAT box.