Analysis of information sources in references of the Wikipedia article "Subnet" in English language version.
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.
the first [...] subnet[...], known as subnet zero
[...] the last subnet[...], known as [...] the all-ones subnet
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.
This practice is obsolete! Modern software will be able to utilize all definable networks.(Informational RFC, demoted to category Historic)
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.)
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.)
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.)
On inter-router point-to-point links, it is useful, for security and other reasons, to use 127-bit IPv6 prefixes.
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).
There are no broadcast addresses in IPv6, their function being superseded by multicast addresses.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.
This anycast address is syntactically the same as a unicast address for an interface on the link with the interface identifier set to zero.
APNIC, ARIN, and RIPE have revised the end site assignment policy to encourage the assignment of smaller (i.e., /56) blocks to end sites.
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.
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.
This practice is obsolete! Modern software will be able to utilize all definable networks.(Informational RFC, demoted to category Historic)
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.)
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.)
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.)
On inter-router point-to-point links, it is useful, for security and other reasons, to use 127-bit IPv6 prefixes.
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).
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.
This anycast address is syntactically the same as a unicast address for an interface on the link with the interface identifier set to zero.
APNIC, ARIN, and RIPE have revised the end site assignment policy to encourage the assignment of smaller (i.e., /56) blocks to end sites.
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.
the first [...] subnet[...], known as subnet zero
[...] the last subnet[...], known as [...] the all-ones subnet
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.
APNIC, ARIN, and RIPE have revised the end site assignment policy to encourage the assignment of smaller (i.e., /56) blocks to end sites.
