サブネット【subnet】
読み方：さぶねっと
コンピューターネットワークにおいて、小さな単位に分割されたネットワークを指す。
サブネット
出典: フリー百科事典『ウィキペディア（Wikipedia）』 (2023/11/24 08:20 UTC 版)
サブネット（英語: subnet）とは、IPネットワークを論理的に細分化したもののことである[1]:1,16。1つのネットワークを2つ以上のネットワークに分割することをサブネット化（subnetting）という 。
- ^ Jeffrey Mogul; Jon Postel (August 1985). Internet Standard Subnetting Procedure (英語). IETF. doi:10.17487/RFC0950. RFC 950。 Updated by RFC 6918.
- ^ V. Fuller; T. Li (August 2006). Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan (英語). Network Working Group. doi:10.17487/RFC4632. RFC 4632。
- ^ R. Braden, ed. (October 1989). Requirements for Internet Hosts -- Communication Layers (英語). Network Working Group IETF. sec. 3.3.1. doi:10.17487/RFC1122. RFC 1122。 Updated by RFC 1349, RFC 4379, RFC 5884, RFC 6093, RFC 6298, RFC 6633, RFC 6864, RFC 8029.
- ^ T. Narten; E. Nordmark; W. Simpson; H. Soliman (September 2007). Neighbor Discovery for IP version 6 (IPv6) (英語). Network Working Group. doi:10.17487/RFC4861. RFC 4861。
- ^ H. Singh; W. Beebee; E. Nordmark (July 2010). IPv6 Subnet Model: The Relationship between Links and Subnet Prefixes (英語). IETF. doi:10.17487/RFC5942. RFC 5942。
- ^ “Document ID 13711 - Subnet Zero and the All-Ones Subnet”. Cisco Systems (2005年8月10日). 2010年4月25日閲覧。 “Traditionally, it was strongly recommended that subnet zero and the all-ones subnet not be used for addressing. [...] Today, the use of subnet zero and the all-ones subnet is generally accepted and most vendors support their use.”
- ^ “Document ID 13711 - Subnet Zero and the All-Ones Subnet”. Cisco Systems (2005年8月10日). 2010年4月23日閲覧。 “the first [...] subnet[...], known as subnet zero”
- ^ “Document ID 13711 - Subnet Zero and the All-Ones Subnet”. Cisco Systems (2005年8月10日). 2010年4月23日閲覧。 “[...] the last subnet[...], known as [...] the all-ones subnet”
- ^ Jeffrey Mogul; Jon Postel (August 1985). Internet Standard Subnetting Procedure (英語). IETF. p. 6. doi:10.17487/RFC0950. RFC 950.
It is useful to preserve and extend the interpretation of these special addresses in subnetted networks. This means the values of all zeros and all ones in the subnet field should not be assigned to actual (physical) subnets.
- ^ Troy Pummill; Bill Manning (December 1995). Variable Length Subnet Table For IPv4 (英語). IETF. doi:10.17487/RFC1878. RFC 1878.
This practice is obsolete! Modern software will be able to utilize all definable networks.
(Informational RFC, demoted to category Historic) - ^ A. Retana; R. White; V. Fuller; D. McPherson (December 2000). Using 31-Bit Prefixes on IPv4 Point-to-Point Links (英語). doi:10.17487/RFC3021. RFC 3021。
- ^ R. Hinden; S. Deering (February 2006). IP Version 6 Addressing Architecture - section 2.5.1. Interface Identifiers (英語). IETF. sec. 2.5.1. doi:10.17487/RFC4291. RFC 4291.
For all unicast addresses, except those that start with the binary value 000, Interface IDs are required to be 64 bits long and to be constructed in Modified EUI-64 format.
(Updated by RFC 5952, RFC 6052, RFC 7136, RFC 7346, RFC 7371, RFC 8064.) - ^ S. Thomson; T. Narten; T. Jinmei (September 2007). IPv6 Stateless Address Autoconfiguration - section 5.5.3.(d) Router Advertisement Processing (英語). IETF. sec. 5.5.3. doi:10.17487/RFC4862. RFC 4862.
It is the responsibility of the system administrator to ensure that the lengths of prefixes contained in Router Advertisements are consistent with the length of interface identifiers for that link type. [...] an implementation should not assume a particular constant. Rather, it should expect any lengths of interface identifiers.
(Updated by RFC 7527.) - ^ M. Crawford (December 1998). Transmission of IPv6 Packets over Ethernet Networks - section 4 Stateless Autoconfiguration (英語). IETF. sec. 4. doi:10.17487/RFC2464. RFC 2464.
The Interface Identifier [AARCH] for an Ethernet interface is based on the EUI-64 identifier [EUI64] derived from the interface's built-in 48-bit IEEE 802 address. [...] An IPv6 address prefix used for stateless autoconfiguration [ACONF] of an Ethernet interface must have a length of 64 bits.
(Updated by RFC 6085, RFC 8064.) - ^ M. Kohno; B. Nitzan; R. Bush; Y. Matsuzaki; L. Colitti; T. Narten (April 2011). Using 127-Bit IPv6 Prefixes on Inter-Router Links (英語). IETF. doi:10.17487/RFC6164. RFC 6164.
On inter-router point-to-point links, it is useful, for security and other reasons, to use 127-bit IPv6 prefixes.
- ^ W. George (February 2012). RFC 3627 to Historic Status to Historic Status (英語). IETF. doi:10.17487/RFC6547. RFC 6547。 "This document moves "Use of /127 Prefix Length Between Routers Considered Harmful" (RFC 3627) to Historic status to reflect the updated guidance contained in "Using 127-Bit IPv6 Prefixes on Inter-Router Links" (RFC 6164)."
- ^ R. Hinden; S. Deering (February 2006). IP Version 6 Addressing Architecture - section 2 IPv6 Addressing (英語). IETF. sec. 2. doi:10.17487/RFC4291. RFC 4291.
There are no broadcast addresses in IPv6, their function being superseded by multicast addresses. [...] In IPv6, all zeros and all ones are legal values for any field, unless specifically excluded.
- ^ R. Hinden; S. Deering (February 2006). IP Version 6 Addressing Architecture - section 2.6.1 Required Anycast Address (英語). IETF. sec. 2.6.1. doi:10.17487/RFC4291. RFC 4291.
This anycast address is syntactically the same as a unicast address for an interface on the link with the interface identifier set to zero.
- ^ “IPv6 Addressing Plans”. ARIN IPv6 Wiki. 2010年4月25日閲覧。 “All customers get one /48 unless they can show that they need more than 65k subnets. [...] If you have lots of consumer customers you may want to assign /56s to private residence sites.”
- ^ T. Narten; G. Huston; L. Roberts (March 2011). IPv6 Address Assignment to End Sites (英語). IETF. doi:10.17487/RFC6177. ISSN 2070-1721. BCP 157. RFC 6177.
APNIC, ARIN, and RIPE have revised the end site assignment policy to encourage the assignment of smaller (i.e., /56) blocks to end sites.
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