Example 2 What is the subnetwork address if the destination address is 19.30.80.5 and the mask is255.255.192.0? IP Address Solution 19 30 5 255 255 192 19+.30 64 0 Subnet Address 84 0 010100 11000000 6401000000 cs爬,NTUT, TANAN
CSIE, NTUT, TAIWAN 16 Example 2 What is the subnetwork address if the destination address is 19.30.80.5 and the mask is 255.255.192.0? Solution
Comparison of a default mask and a subnet mask 255.255.0.0 Default Mask 11111111 11111111 00000000 00000000 255.255.224.0 Subnet Mask 11111111 11111111 00000 00000000 13 CSIE NTUT TANAN Figure 5-7
CSIE, NTUT, TAIWAN 17 Figure 5-7 Comparison of a default mask and a subnet mask
Number of subnetworks addresses Number of subnetworks number of extra is that are added to the default mask to make the subnet mask Number of addresses per subnet num ber of os in the subnet mask CSIE NTUT TANAN
CSIE, NTUT, TAIWAN 18 Number of subnetworks, addresses • Number of subnetworks number of extra 1s that are added to the default mask to make the subnet mask • Number of addresses per subnet number of 0s in the subnet mask
Special addresses Hostid all os- subnet address Hostid all ls- limited broadcast inside the subnet CSIE NTUT TANAN
CSIE, NTUT, TAIWAN 19 Special addresses • Hostid all 0s – subnet address • Hostid all 1s – limited broadcast inside the subnet
Designing subnets Deciding the number of subnets The num ber of subnets must be a power of 2 Finding the subnet mask Find the number of is in the default mask Find the number of is that define the subnets Add the number of ls in above steps Find the number of os Finding the range of address in each subnet CSIE NTUT TANAN
CSIE, NTUT, TAIWAN 20 Designing Subnets • Deciding the number of subnets The number of subnets must be a power of 2 • Finding the subnet mask – Find the number of 1s in the default mask – Find the number of 1s that define the subnets – Add the number of 1s in above steps – Find the number of 0s • Finding the range of address in each subnet