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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)                 9  Internet Protocol Version 4 (IP, IPv4)                      9  IP Addressing                           9  IP "Classful" (Conventional) Addressing

IP Multicast Addressing 1 2 3 IP Subnet Addressing ("Subnetting") Concepts

Tactics for Dealing with “Classful” Addressing Difficulties

These issues were addressed through three enhancements or improvements that I discuss in other sections. The first, which primarily addresses Issue #1, was the development of subnetting. The second was the move to classless addressing and routing, which replaces the “classful” system with a new method with higher granularity. This tackles Issues #2 and #3 by letting addresses be assigned based on real organizational needs without requiring numerous routing table entries for each organization. The third improvement is the new IP version 6 protocol, which finally does away with the cramped 32-bit IP address space in favor of a gargantuan 128-bit one.

Other support technologies have also helped extend the life of IP version 4. I discussed one important one in the previous topic—the use of private addressing in conjunction with IP Network Address Translation (NAT) to allow multiple devices to share public addresses. This alone has added years to the life of the IPv4 addressing system.

IP Multicast Addressing 1 2 3 IP Subnet Addressing ("Subnetting") Concepts