{"id":312,"date":"2018-03-09T08:44:56","date_gmt":"2018-03-09T08:44:56","guid":{"rendered":"http:\/\/www.certexams.com\/Blog\/?p=312"},"modified":"2018-03-09T09:00:56","modified_gmt":"2018-03-09T09:00:56","slug":"ipv6-subnetting","status":"publish","type":"post","link":"https:\/\/www.certexams.com\/Blog\/2018\/03\/09\/ipv6-subnetting\/","title":{"rendered":"IPv6 Subnetting"},"content":{"rendered":"

An IPv6 address<\/strong> consists of 128 bits<\/strong> and includes bits to be used for subnetting.\u00a0 The first half of the subnet (64 bits) consists of routing prefix (48 bits) and subnet ID (16 bits) and the second half of the address (64 bits) is used for hosts only. This is in contrast with the IPv4 network, wherein the host bits are borrowed to divide the network into subnets. In IPv6, the least significan 64 bits are always used for representing hosts. 16 bits are separately identified for subnetworks.<\/p>\n

\"\"<\/p>\n

\/48 prefix is\u00a0 allocated to an organization which can offer up to \/64 subnet prefixes, equivalent to 65535 sub-networks, each having 264<\/sup> hosts. A \/64 prefix can be assigned to a point-to-point connection where there are only two hosts (or IPv6 enabled devices) on a link. Typical allowcation of IPv6 addresses is given below:<\/p>\n

IPv6 CIDR Subnet \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 Number of IPs<\/p>\n

Residential \u2013 \/64 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 18,446,744,073,709,551,616
\nBusiness \u2013 \u00a0\u00a0 \/48\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1,208,925,819,614,629,174,706,176
\nISP \u2013 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/32\u00a0\u00a0 79,228,162,514,264,337,593,543,950,336<\/p>\n

As you may see from the above table, residential user is allocated \/64 prefix address, business user may be allocated \/48 address, and ISPs will have \/32 address prefix, I’m not sure if there is any term to describe the numbers;<\/p>\n

An example of\u00a0 IPv6 address subnetting:<\/h3>\n

Assume that an ISP has provided a 48-bit prefix to the user. Consider the address and prefix
\n2001:0867:5208\/48 for instance. Because each four hexadecimal digits are 16 bits, and the last 64 bits are usually the interface identifier (the \u201chost\u201d portion of the address in IPv4), this leaves 16 bits for subnetting. Assume the subnet bits, assigned locally, for a certain subnet are 72cd.
\nThis subnet would allow addresses in the range:<\/p>\n

2001:0867:530972cd:0000:0000:0000:0001 to 2001:0867:530972cd:ffff:ffff:ffff:ffff<\/p>\n

So, when subnetted, an IPv6 address consists of three parts:<\/p>\n