ZyXEL Communications wireless n gigabit netusb router User Manual

NBG4615 User’s Guide

IPv6 (Internet Protocol version 6), is designed to enhance IP address size and features. The 
increase in IPv6 address size to 128 bits (from the 32-bit IPv4 address) allows up to 3.4 x 1038 IP 
addresses. 

• See 

 for more information on IPv6.

The 128-bit IPv6 address is written as eight 16-bit hexadecimal blocks separated by colons (:). This 
is an example IPv6 address 2001:0db8:1a2b:0015:0000:0000:1a2f:0000.

IPv6 addresses can be abbreviated in two ways:

• Leading zeros in a block can be omitted. So 2001:0db8:1a2b:0015:0000:0000:1a2f:0000 can 

be written as 2001:db8:1a2b:15:0:0:1a2f:0. 

• Any number of consecutive blocks of zeros can be replaced by a double colon. A double colon can 

only appear once in an IPv6 address. So 2001:0db8:0000:0000:1a2f:0000:0000:0015 can be 
written as 2001:0db8::1a2f:0000:0000:0015, 2001:0db8:0000:0000:1a2f::0015, 
2001:db8::1a2f:0:0:15

 or 2001:db8:0:0:1a2f::15.

Similar to an IPv4 subnet mask, IPv6 uses an address prefix to represent the network address. An 
IPv6 prefix length specifies how many most significant bits (start from the left) in the address 
compose the network address. The prefix length is written as “/x” where x is a number. For 
example, 

2001:db8:1a2b:15::1a2f:0/32

means that the first 32 bits (2001:db8) is the subnet prefix. 

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.