RFC 1519 (rfc1519) - Page 2 of 24
Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy
Alternative Format: Original Text Document
RFC 1519 CIDR Address Strategy September 1993 5.1 Address allocation .......................................... 15 5.2 Routing advertisements ...................................... 17 6. Extending CIDR to class A addresses .......................... 18 7. Domain Naming Service considerations ......................... 20 7.1 Procedural changes for class-C "supernets" ................... 20 7.2 Procedural changes for class-A subnetting .................... 21 8. Transitioning to a long term solution ........................ 22 9. Conclusions .................................................. 22 10. Recommendations ............................................. 22 11. References .................................................. 23 12. Security Considerations ..................................... 23 13. Authors' Addresses .......................................... 24 Acknowledgements The authors wish to express their appreciation to the members of the ROAD group with whom many of the ideas contained in this document were inspired and developed. 1. Problem, Goal, and Motivation As the Internet has evolved and grown over in recent years, it has become evident that it is soon to face several serious scaling problems. These include: 1. Exhaustion of the class B network address space. One fundamental cause of this problem is the lack of a network class of a size which is appropriate for mid-sized organization; class C, with a maximum of 254 host addresses, is too small, while class B, which allows up to 65534 addresses, is too large for most organizations. 2. Growth of routing tables in Internet routers beyond the ability of current software, hardware, and people to effectively manage. 3. Eventual exhaustion of the 32-bit IP address space. It has become clear that the first two of these problems are likely to become critical within the next one to three years. This memo attempts to deal with these problems by proposing a mechanism to slow the growth of the routing table and the need for allocating new IP network numbers. It does not attempt to solve the third problem, which is of a more long-term nature, but instead endeavors to ease enough of the short to mid-term difficulties to allow the Internet to continue to function efficiently while progress is made on a longer- term solution. Fuller, Li, Yu & Varadhan
