Chapter 7 Interfaces

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 ZyWALL’s WAN interface is connected to an ISP with a router and the ZyWALL is set to automatically obtain an IPv6 network prefix from the router for the interface, it generates 1another address which combines its interface ID and global and subnet information advertised from the router. This is a routable global IP address.

Prefix Delegation

Prefix delegation enables an IPv6 router (the ZyWALL) to use the IPv6 prefix (network address) received from the ISP (or a connected uplink router) for its LAN. The ZyWALL 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 in the same network.

DHCPv6

The Dynamic Host Configuration Protocol for IPv6 (DHCPv6, RFC 3315) is a server-client protocol that allows a DHCP server to assign and pass IPv6 network addresses, prefixes and other configuration information to DHCP clients. DHCPv6 servers and clients exchange DHCP messages using UDP.

Each DHCP client and server has a unique DHCP Unique IDentifier (DUID), which is used for identification when they are exchanging DHCPv6 messages. The DUID is generated from the MAC address, time, vendor assigned ID and/or the vendor's private enterprise number registered with the IANA. It should not change over time even after you reboot the device.

Finding Out More

•See Section 7.10 on page 172 for background information on interfaces.

•See Chapter 8 on page 177 to configure load balancing using trunks.

1.In IPv6, all network interfaces can be associated with several addresses.

 

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ZyWALL 110/310/1100 Series User’s Guide