ZyXEL Communications SBG5500-A User Manual page 51

• 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.
IPv6 Prefix and Prefix Length
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.
IPv6 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.
IPv6 Rapid Deployment
Use IPv6 Rapid Deployment (6rd) when the local network uses IPv6 and the ISP has an IPv4 network.
When the SBG has an IPv4 WAN address and you set IPv4/IPv6 Mode to IPv4 Only, you can enable 6rd
to encapsulate IPv6 packets in IPv4 packets to cross the ISP's IPv4 network.
The SBG generates a global IPv6 prefix from its IPv4 WAN address and tunnels IPv6 traffic to the ISP's
Border Relay router (BR in the figure) to connect to the native IPv6 Internet. The local network can also
use IPv4 services. The SBG uses it's configured IPv4 WAN IP to route IPv4 traffic to the IPv4 Internet.
Figure 43 IPv6 Rapid Deployment
Chapter 5 WAN/Internet
SBG
SBG5500 Series User's Guide
51