IPv6 Protocol address type

All types of IPv6 addresses are allocated to interfaces instead of nodes. The IPv6 address specifies a 128-bit identifier for the interface and interface group. There are three types of addresses:

[1] Unicast) Address: a single interface has an identifier, and the packet sent to a Unicast address is transmitted to the interface identified by this address. For a node with multiple interfaces, any one of its unicast addresses can be used as the identifier of the node. An IPv6 unicast address is an address that is aggregated with a continuous bit mask, similar to an IPv4 address of CIDR. Unicast addresses in IPv6 are allocated in multiple forms, this includes all the globally available unicast addresses, NSAP addresses, IPX hierarchical addresses, site local addresses, link local addresses, and host addresses running IPv 4. Unicast addresses include the following two special addresses:

● Unspecified address:

Unicast address 0: 0: 0: 0: 0: 0: 0: 0: 0 is called an unspecified address. It cannot be assigned to any node. This address does not exist. An example of its application is that when the host is initialized, you can put unspecified addresses in the source address field of any IPv6 package it sends before the host has obtained its own address. The unspecified address cannot be used as the destination address in the IPv6 package or in the IPv6 Routing header.

● Return address:

Unicast address 0: 0: 0: 0: 0: 0: 0: 0: 1 is called return address. The node uses it to send IPv6 packets to itself. It cannot be assigned to any physical interface.

[2] AnyCast address: Generally, an interface group of different nodes has an identifier, A packet sent to any multicast address is sent to an interface identified by the address that measures the nearest distance based on the routing protocol. Any IPv6 multicast address has the following restrictions:

● Any stream play address cannot be used as the source address, but only as the target address.

● Any multicast address cannot be specified to an IPv6 host, but can only be specified to an IPv6 router.

Figure 1: IPv6 multicast address

[3] MultiCast) Address: Generally, an interface group of different nodes has an identifier. The packet sent to a MultiCast address is transmitted to all interfaces identified by this address. 1111 1111 at the beginning of the address identifies the address as the multicast address.

Figure 2: IPv6 multicast address

IPv6 does not have a broadcast address. Its function is being replaced by a multicast address. In addition, in IPv6, all "0" and "1" fields are valid unless otherwise excluded. In particular, the prefix can contain the "0" value field or end with "0. A single interface can specify multiple types of IPv6 addresses for unicast, multicast, Or multicast) or range.

In addition to the 128-bit Address space, IPv6 also designs an Address with a hierarchical structure for point-to-point communication. This Address is called Aggregatable Global Unicast Address ), the clustering address is defined in RFC2374 as a hierarchical structure with three layers:

Public Topology

Site Topology

Interface identifier

A public topology is a supplier and exchange group that provides public Internet transfer services. The site topology is a specific local site or organization. It does not provide public transfer services to nodes other than the site. An interface identifier is an interface that identifies a link.

The hierarchical structure of clustered global unicast addresses is shown in 3. The first three addresses are the prefix of the address type, which is used to distinguish other address types. The subsequent 13-bit tla id, 32-bit nla id, 16-bit sla id, and 64-bit host interface ID are used to identify the Top-down TLA Level Aggregator in the hierarchical structure, top aggregate), NLANext Level Ag gregator, lower aggregate), SLASite Level Aggregator, location aggregate) and host interface. RES reserved for future TLA or NLA extension. TLA is a public network access point that is connected to long-distance service providers and telephone companies. It obtains the address from an international Internet Registrar such as IANA. NLA is usually a large ISP. It requests an address from TLA and assigns an address to the SLA. SLA can also be referred to as user subscriber). It can be an organization or a small ISP. The SLA is responsible for allocating addresses to its subscribers. The SLA usually assigns its subscribers an address block consisting of consecutive addresses so that these organizations can establish their own address hierarchical structure to identify different subnets. The bottom of the hierarchical structure is the network host.

Figure 3: definitions of globally multicast addresses that can be clustered in RFC 2373

The address format is designed to support both the clustering based on the current supplier and the new clustering type called the Exchange Board. Its Combination enables efficient route aggregation to be used to directly connect to the vendors and sites connected to the Exchange Board. The site can be connected to any of the two types of clustering points.

Table 1: IPv6 address space allocation

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