108 Configuring System InformationIPv6 SyntaxThe 128-bit IPv6 address format is divided into eight groups of four hexadecimal digits. Abbreviation ofthis format by replacing a group of zeros with "double colons" (::) is acceptable. IPv6 addressrepresentation can be further simplified by suppressing the leading zeros.All different IPv6 address formats are acceptable for insertion, yet for display purposes, the system willdisplay the most abbreviated form, which replaces groups of zeros with "double colons" and removes the"leading zeros".IPv6 PrefixesWhile unicast IPv6 addresses written with their prefix lengths are permitted, in practice their prefixlengths are always 64 bits and therefore are not required to be expressed. Any prefix that is less than64 bits is a route or address range that is summarizing a portion of the IPv6 address space.For every assignment of an IP address to an interface, the system runs the Duplicate Address Detection(DAD) algorithm to ensure uniqueness.An intermediary transition mechanism is required for IPv6-only nodes to communicate with IPv6 nodesover an IPv4 infrastructure. The tunneling mechanism implemented is the Intra-Site Automatic TunnelAddressing Protocol (ISATAP). This protocol treats the IPv4 network as a virtual IPv6 local-link,with each IPv4 address mapped to a Link Local IPv6 address.To open the IP Addressing page, click System → IP Addressing in the tree view.Defining IPv4 Default GatewaysThe IPv4 Default Gateway page contains fields for assigning Gateway devices. Packets are forwarded tothe default IP when frames are sent to a remote network. The configured IP address must belong to thesame IP address subnet of one of the IP interfaces. To open the IPv4 Default Gateway page,click System→ IP Addressing → IPv4 Default Gateway in the tree view.Figure 6-22. IPv4 Default Gateway
