These are usually grouped into groups of 8 bits called bytes. The bytes are then translated into decimal numbers. These in turn have dots '. IPv6 addresses are bits or 16 bytes. Configuring the inet6 IPv6 Protocol Family. IPv4 addresses are bit numbers that are typically displayed in dotted decimal notation and contains two primary parts: the network prefix and the host number. IPv4 addresses are bit numbers that are typically displayed in dotted decimal notation. A bit address contains two primary parts: the network prefix and the host number.
All hosts within a single network share the same network address. Each host also has an address that uniquely identifies it. Depending on the scope of the network and the type of device, the address is either globally or locally unique.
Devices that are visible to users outside the network webservers, for example must have a globally unique IP address. Devices that are visible only within the network must have locally unique IP addresses. IANA ensures that addresses are globally unique where needed and has a large address space reserved for use by devices not visible outside their own networks.
To provide flexibility in the number of addresses distributed to networks of different sizes, 4-octet bit IP addresses were originally divided into three different categories or classes: class A, class B, and class C. Each address class specifies a different number of bits for its network prefix and host number:.
Class A addresses use only the first byte octet to specify the network prefix, leaving 3 bytes to define individual host numbers. Class B addresses use the first 2 bytes to specify the network prefix, leaving 2 bytes to define host addresses. Class C addresses use the first 3 bytes to specify the network prefix, leaving only the last byte to identify hosts. In binary format, with an x representing each bit in the host number, the three address classes can be represented as follows:.
Because each bit x in a host number can have a 0 or 1 value, each represents a power of 2. For example, if only 3 bits are available for specifying the host number, only the following host numbers are possible:.
In each IP address class, the number of host-number bits raised to the power of 2 indicates how many host numbers can be created for a particular network prefix. Class A addresses have 2 24 or 16,, possible host numbers, class B addresses have 2 16 or 65, host numbers, and class C addresses have 2 8 or possible host numbers.
The bit IPv4 addresses are most often expressed in dotted decimal notation, in which each octet or byte is treated as a separate number. Within an octet, the rightmost bit represents 2 0 or 1 , increasing to the left until the first bit in the octet is 2 7 or Following are IP addresses in binary format and their dotted decimal equivalents:. Because of the physical and architectural limitations on the size of networks, you often must break large networks into smaller subnetworks.
Within a network, each wire or ring requires its own network number and identifying subnet address. Figure 1 shows two subnets in a network.
Figure 1 shows three devices connected to one subnet and three more devices connected to a second subnet. Collectively, the six devices and two subnets make up the larger network. In this example, the network is assigned the network prefix Each device has an IP address that falls within this network prefix.
In addition to sharing a network prefix the first two octets , the devices on each subnet share a third octet. The third octet identifies the subnet. All devices on a subnet must have the same subnet address. In this case, the alpha subnet has the IP address The subnet address Because the first 24 bits in the bit address identify the subnet, the last 8 bits are not significant.
To indicate the subnet, the address is written as The IPv6 address consists mainly of two bit segments where the higher part of the bits is classified as the network part, and the lower 64 bits are classified as the client ID.
This information can be simplified by the following picture:. It is worth noting that IPv6 has no notion of subnet masks like IPv4 has. Examples are:. The Unicast address type is probably the most important one. It distinguishes itself by these sub-type addresses:. Multicast is the technique used to send a packet from one source or multiple sources to multiple destinations receivers. In its simplest form, a multicast flow is as follows.
First, a host sends an ICMPv6 packet host solicitation to the router s multicast group. Then, a router responds to this request and sends a Router Advertisement RA packet back to the client along with configuration parameters:.
The Anycast address behaves similarly to the Multicast address, except for the following. A packet sent from a client goes to a single selected destination and not to the whole group identified by the same destination address. The receiving endpoint is selected based on the least expensive routing metric. The router uses the equal-cost multi-path to do this:. Eventually, we will all be using IPv6. For example, the IPv6 address dbc4ddeee can be collapsed into dbc4ddeee The leftmost fields of the IPv6 address contain the prefix, which is used for routing IPv6 packets.
IPv6 prefixes have the following format:. Prefix length is stated in classless inter-domain routing CIDR notation. CIDR notation is a slash at the end of the address that is followed by the prefix length in bits. The site prefix of an IPv6 address occupies up to 48 of the leftmost bits of the IPv6 address. You use the following representation, with zeros compressed, to represent this prefix:. You can also specify a subnet prefix , which defines the internal topology of the network to a router.
The example IPv6 address has the following subnet prefix. The subnet prefix always contains 64 bits. These bits include 48 bits for the site prefix, in addition to 16 bits for the subnet ID.
The type of unicast address is determined by the leftmost high order contiguous bits in the address, which contain the prefix. The global unicast address is globally unique in the Internet. The next figure shows the scope of the global unicast address, as compared to the parts of the IPv6 address.
The site prefix defines the public topology of your network to a router. IN IPv6, the subnet ID defines an administrative subnet of the network and is up to 16 bits in length.
You assign a subnet ID as part of IPv6 network configuration. The subnet prefix defines the site topology to a router by specifying the specific link to which the subnet has been assigned. IPv6 subnets are conceptually the same as IPv4 subnets, in that each subnet is usually associated with a single hardware link. However, IPv6 subnet IDs are expressed in hexadecimal notation, rather than in dotted decimal notation.
The interface ID identifies an interface of a particular node.
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