© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Introduction to IPv6 Explaining the rationale for IPv6

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IP Address Allocation History IPv4 published 1985 ~ 1/16 of total space 1990 ~ 1/8 of total space 1995 ~ 1/3 of total space 2000 ~ 1/2 of total space 2003 ~ 2/3 of total space 2005 ~ 3/4 of total space This despite increasingly intense conservation efforts, including: PPP and DHCP address sharing CIDR, VLSM Theoretical limit of 32-bit space: ~4.3 billion devices Practical limit of 32-bit space: ~250 million devices (RFC 3194) NAT Address reclamation

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IP Address Allocation History (Cont.) IPv4 published 1985 ~ 1/16 of total space 1990 ~ 1/8 of total space 1995 ~ 1/3 of total space 2000 ~ 1/2 of total space 2003 ~ 2/3 of total space This despite increasingly intense conservation efforts PPP and DHCP address sharing CIDR Theoretical limit of 32-bit space: ~4.3 billion devices Practical limit of 32-bit space: ~250 million devices (RFC 3194) NAT Address reclamation

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Features Issues in IPv4 IPv4 was designed without a number of modern-day network requirements in mind. Security: IPsec Device roaming: Mobile IP Quality of service: RSVP, others Address scarcity: DHCP, NAT, CIDR, VLSM Others

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv4 Improvement Opportunities More than 20 years of IPv4 use have identified several opportunities for improvement: Variable-length options, padding inefficient Fragmentation process creates undue overhead, necessitates use of the Flag, Fragment Offset, and Header Checksum fields Inefficient to add new services to IPv4 packet

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Short History of IPv DARPA is commissioned by DoD for research networking. First public test of ARPANET held at ICCC in Washington, D.C. Kahn and Cerf push concept of Internet. TCP is split into TCP and IP. IPv4 specification is published in RFC 791. Mosaic is released. World Wide Web is developed. Kahn and Cerf publish the details for TCP NAT developed, RFC % of IPv4 32-bit address space allocated CIDR published, RFC % of IPv4 32-bit address space allocated.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Short History of IPv Prediction of exhaustion of IPv4 Class B by ROAD group formed to address routing. Prediction of exhaustion of IPv4 addresses by 2005–2011. IPng proposals solicitation (RFC 1550). CATNIP, SIPP, TUBA analyzed; SIPP+ chosen. IPng workgroup started. First specification: RFC First attempt at provider-based address format. First IPv6 exchange: 6tap. Registries assign IPv6 prefixes. IPv6 Forum formed. Major vendors bundle IPv6 in their mainstream product lines. 6bone started Release of Cisco IOS 12.3 Mainline (richly featured IPv6 version) NAT RFC approved (RFC 1631now out of date).

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v What Happened to IPv5? IPv5 is the IP protocol number of the Internet Stream Protocol, because it uses the same link-layer framing as IPv4. –Experimental protocol –Addresses resource reservation –Designed to coexist with IPv4, not a replacementsame addressing scheme Resource reservation is now done using other protocols.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v IPv4 Workarounds In order to extend the lifetime and usefulness of IPv4 and circumvent address shortage, several mechanisms were created: CIDR NAT VLSM DHCP

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Network Address Translation NAT provides a way to hide many internal addresses behind one or a small number of routable addresses. NAT has many implications: –Breaks the end-to-end model of IP –Mandates that the network keeps state of the connections –Makes fast rerouting difficult NAT Device Internet

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Network Address Translation (Cont.) NAT has additional implications: Inhibits end-to-end network security Requires upgrade when a new application is not NAT-friendly Application Layer Gateways not as fast as IP routing Merging of private networks difficult

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v NAT Inhibits Access to Internal Servers When many internal servers need to be reachable from outside, NAT becomes an important issue. Global Addressing Realm

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v Summary The adoption of networking and particular services, such as and the web, drove IPv4 address consumption. Initial inefficient IPv4 address allocation methods and subsequent growth of the Internet is exhausting the IPv4 address space. Advanced features, such as quality of service, IP security (IPsec), and the growing scarcity of IPv4 addresses prompted the development of IPv6. NAT, while stalling IPv4 address exhaustion, has several limitations, including inhibiting end-to-end security and increasing the complexity of network administration.

© 2006 Cisco Systems, Inc. All rights reserved.IP6FD v