ZyXEL ZyWALL ATP700 User Guide - Page 242
Link-local Address, Subnet Masking, Stateless Autoconfiguration, Prefix Delegation, IPv6 Router
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Chapter 9 Interfaces Link-local Address A link-local address uniquely identifies a device on the local network (the LAN). It is similar to a "private IP address" in IPv4. You can have the same link-local address on multiple interfaces on a device. A linklocal unicast address has a predefined prefix of fe80::/10. The link-local unicast address format is as follows. Table 97 Link-local Unicast Address Format 1111 1110 10 0 Interface ID 10 bits 54 bits 64 bits Subnet Masking Both an IPv6 address and IPv6 subnet mask compose of 128-bit binary digits, which are divided into eight 16-bit blocks and written in hexadecimal notation. Hexadecimal uses four bits for each character (1 ~ 10, A ~ F). Each block's 16 bits are then represented by four hexadecimal characters. For example, FFFF:FFFF:FFFF:FFFF:FC00:0000:0000:0000. Stateless Autoconfiguration With stateless autoconfiguration in IPv6, addresses can be uniquely and automatically generated. Unlike DHCPv6 (Dynamic Host Configuration Protocol version six) which is used in IPv6 stateful autoconfiguration, the owner and status of addresses don't need to be maintained by a DHCP server. Every IPv6 device is able to generate its own and unique IP address automatically when IPv6 is initiated on its interface. It combines the prefix and the interface ID (generated from its own Ethernet MAC address) to form a complete IPv6 address. When IPv6 is enabled on a device, its interface automatically generates a link-local address (beginning with fe80). When the Zyxel Device's WAN interface is connected to an ISP with a router and the Zyxel Device is set to automatically obtain an IPv6 network prefix from the router for the interface, it generates another address which combines its interface ID and global and subnet information advertised from the router. (In IPv6, all network interfaces can be associated with several addresses.) This is a routable global IP address. Prefix Delegation Prefix delegation enables an IPv6 router (the Zyxel Device) to use the IPv6 prefix (network address) received from the ISP (or a connected uplink router) for its LAN. The Zyxel Device uses the received IPv6 prefix (for example, 2001:db2::/48) to generate its LAN IP address. Through sending Router Advertisements (RAs) regularly by multicast, the router passes the IPv6 prefix information to its LAN hosts. The hosts then can use the prefix to generate their IPv6 addresses. IPv6 Router Advertisement An IPv6 router sends router advertisement messages periodically to advertise its presence and other parameters to the hosts on the same network. ZyWALL ATP Series User's Guide 242