Special ipv4 loopback iana reserved mac#

Figure 5. IPv6 Link-local address structure The structure of a link-local address is shown in Figure 4.

Special ipv4 loopback iana reserved mac#

IPv6 link-local is a special type of unicast address that is auto-configured on any interface using a combination of the link-local prefix FE80::/10 (first 10 bits equal to 1111 1110 10) and the MAC address of the interface. Figure 4. IPv6 Allocation Example Link-Local That's is why these global IPv6 unicast addresses are called aggregatable. Note that the prefix was given to Customer 1 2001:18B1:1::/48 is part of the bigger prefix 2001:18B1::/32 owned by the ISP, which itself is part of the bigger prefix 2001:18::/23 of ARIN and so on. ARIN then allocates sub-parts of this address space 2001:18::/23 to ISPs and large customers.For example, part of this address space is allocated to ARIN.IANA currently allocates addresses from the prefix 2000::/3 to the regional providers.Let's take a look at the following example of allocating global unicast addresses. Their structure consists of a 48-bit global routing prefix and a 16-bit subnet ID also referred to as Site-Level Aggregator (SLA). At present, all global unicast addresses start with binary value 001 (2000::/3). The structure of these addresses enables for aggregation of routing entries to achieve a smaller global IPv6 routing table. Broadcast functionality is implemented using multicast addresses.įigure 2. IPv6 Address Types Unicast Addresses Aggregatable Global Unicast AddressĪggregatable global unicast addresses are part of the global routing prefix. Broadcast- There are no broadcast addresses in IPv6.'Closest' typically means the one with the best routing metric according to the IPv6 routing protocol. Therefore, it is one-to-closest communication. Packets sent to an anycast address are delivered to the 'closest' interface identified by that address. Anycast - A network layer identifier for a set of interfaces, belonging to different IPv6 enabled nodes.Multicast - A network layer identifier for a set of interfaces, belonging to different IPv6 enabled nodes. Packets sent to a multicast address are delivered to all interfaces identified by that address. Therefore, it is one-to-many communication.Unicast - A network layer identifier for a single interface of IPv6 enabled node. Packets sent to a unicast address are delivered to the interface configured with that IPv6 address. Therefore, it is one-to-one communication.

There are three main types of addresses as shown in Figure 2: The IPv6 Address TypesĪn IPv6 address is a 128-bit network layer identifier for a single interface of IPv6 enabled node.

Note the following examples of Global Unicast Addresses: 2001:4::aac4:13a2Īt present, in the Internet IPv6 routing table, all prefixes start with the hexadecimal digit 2 or 3, because IANA allocates only addresses that start with the first 3 bits 001. Figure 1. IANA’s Allocation of IPv6 Address Spaceįigure 1 visualizes the allocation logic. All other possible addresses are reserved for future use and are currently not being allocated. A small portion of the addresses starting with 000 and 111 are allocated for special types. IANA provides global unicast addresses that start with leading leftmost bits 001. The Internet Assigned Numbers Authority (IANA) allocates only a small portion of the whole IPv6 space.

As we already learned, IPv6 addresses are 128-bit long, which means that there are 340 undecillion possible addresses (the exact number is shown below).ģ40,282,366,920,938,463,463,374,607,431,768,211,456įor reference, in IPv4 with its 32-bit address space, there are 4.29 billion possible addresses.