Classless Inter-Domain Routing: Difference between revisions

Revision as of 20:04, 1 September 2025

Revision as of 20:25, 1 September 2025

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| colspan="5" | '''T''' = 1,099,511,627,776

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The large address size of IPv6 permitted worldwide route summarization and guaranteed sufficient address pools at each site. The standard subnet size for IPv6 networks is a {{IPaddr||64}} block, which is required for the operation of [[IPv6 stateless address autoconfiguration|stateless address autoconfiguration]].<ref name="RFC 4862">{{IETF RFC|4862}}</ref> At first, the IETF recommended in {{IETF RFC|3177}} as a best practice that all end sites receive a {{IPaddr||48}} address allocationallocations,<ref name="RFC 3177">{{cite IETF |rfc=3177 |title=IAB/IESG Recommendation on IPv6 Address Allocations to Sites |publisher=IAB/IESG |date=September 2001}}</ref> but criticism and reevaluation of actual needs and practices has led to more flexible allocation recommendations in {{IETF RFC|6177}}<ref name="RFC 6177">{{cite IETF |rfc=6177 |title=IPv6 Address Assignment to End Sites |author=T. Narten |author2=G. Huston |author3=L. Roberts |date=March 2011}}</ref> suggesting a significantly smaller allocation for some sites, such as a {{IPaddr||56}} block for residential networks.

This IPv6 subnetting reference lists the sizes for IPv6 [[subnetwork]]s. Different types of network links may require different subnet sizes.<ref>{{cite web|url=http://www.getipv6.info/index.php/IPv6_Addressing_Plans |title=ARIN IPv6 Addressing Plans |publisher=Getipv6.info |date=2016-03-25 |access-date=2018-03-12}}</ref> The subnet mask separates the bits of the network identifier prefix from the bits of the interface identifier. Selecting a smaller prefix size results in fewer number of networks covered, but with more addresses within each network.<ref>{{cite web |url=https://www.ripe.net/info/info-services/addressing.html |title=RIPE IP Allocation Rates |archive-url=https://web.archive.org/web/20110203130851/http://ripe.net/info/info-services/addressing.html |archive-date=2011-02-03}}</ref>