台北科技大学：《计算机网络》（英文版） NP04 5 Subnetting

Subnetting/Supernetting and Classless addressing Chuan-Ming liu CSIE NTUT Spring 04, TAIWAN CS旧E.NTUT. TAWAN

CSIE, NTUT, TAIWAN 1 Subnetting/Supernetting and Classless Addressing Chuan-Ming Liu CSIE, NTUT Spring ’04, TAIWAN

CONTENTS SUBNETTING SUPERNETTING CLASSLESSADDRSSING CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 2 CONTENTS • SUBNETTING • SUPERNETTING • CLASSLESS ADDRSSING

5。1 SUBNETTING CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 3 SUBNETTING 5.1

Subnetting Network is divided into several smaller subnetworks Each subnetwork(subnet) has its own subnetwork address Hierarchy in IP addressing IP addresses are designed with two levels of hi hierarchy CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 4 Subnetting • Network is divided into several smaller subnetworks • Each subnetwork (subnet) has its own subnetwork address • Hierarchy in IP addressing • IP addresses are designed with two levels of hierarchy

Note IP addresses are designed with CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 5 IP addresses are designed with two levels of hierarchy

network with two levels of hierarchy 41.14.0.1141.14.0.2 14.192.2 141.14.255.254141.14.255.25 Network:141.14.0.0 141.14.2014 RI To the rest the internet CSIE NTUT TANAN Figure 5-1

CSIE, NTUT, TAIWAN 6 Figure 5-1 network with two levels of hierarchy

network with three levels of hierarchy (subnetted) 141.14.0.1141.140.2 141.4.63.254141.14641141.14642 141.14.127.254 Subnet 141.14.88.9 Subnet 141.14.0.0 141.14.64.0 141.14.192.1141.14.192.2 2∞N- 1411425254141.14128114114.128214114191254 Subnet Subnet 141.14.192.0 141.14.128.0 RI Site:141.14.0.0 To the rest of the Internet VAN

CSIE, NTUT, TAIWAN 7 Figure 5-2 network with three levels of hierarchy (subnetted)

Addresses in a network with and without subnetting 141 14 192 Netid Hostid a. Without subnetting 141 14 192 192 Site Subnetid Hostid b. With subnetting CSIE NTUT TANAN 5-3

CSIE, NTUT, TAIWAN 8 Figure 5-3 Addresses in a network with and without subnetting

Hierarchy concept in a telephone number 408 864 8902 Area code Exchange Connection CSIE NTUT TANAN Figure 5-4

CSIE, NTUT, TAIWAN 9 Figure 5-4 Hierarchy concept in a telephone number

Subnet mask Network mask(default mask) creates the network address. subnet mask creates the subnetwork address Contiguous V.S. noncontiguous subnet mask Finding the subnet address Straight method Short-cut method CSIE NTUT TANAN

CSIE, NTUT, TAIWAN 10 Subnet Mask • Network mask (default mask) creates the network address; subnet mask creates the subnetwork address • Contiguous v.s. noncontiguous subnet mask • Finding the subnet address – Straight Method – Short-cut method