IPv6 Addressing

IPv6 Addressing Options

Stateful Address Autoconfiguration. This method allows use of a DHCPv6 server to automatically configure IPv6 addressing on a host in a manner similar to stateful IP addressing with a DHCPv4 server. For software release K.13.01, a DHCPv6 server can provide routable IPv6 addressing and NTP (timep) server addresses. Also, if the host acquires its IPv6 addressing through stateless or static methods, the DHCPv6 server can still be used to automatically provide other configuration information to the host. Refer to page 3-8.

Static Address Configuration. Static configuration is used instead of or in addition to stateless and stateful autoconfiguration where use of the host MAC address does not provide the desired level of address control and distribution. Refer to page 3-9.

Duplicate Address Detection (DAD). IPv6 verifies both the link-local and the global unicast address(es) on each interface for uniqueness, regardless of the method used to configure the address. If an address fails this test, it is identified as a duplicate, and a replacement must be configured using the static method. (To view address status, use the show ipv6 command.) For more information on DAD, refer to “Neighbor Discovery (ND)” on page 4-17.

Developing an Addressing Plan. For small, flat networks and any environ­ ment where control of address assignments need not be restricted or tightly controlled, stateless addressing is adequate for network management and control. Where systematic and controlled addressing is needed, stateful and static addressing methods should be used. Where dual-stack operation is used in a VLAN, incorporating the local IPv4 addressing scheme into the IPv6 addresses you use can help to provide consistency and correspondence among the IPv6 and IPv4 addresses in use on the VLAN.

Related Information.

■RFC 4291: “IP Version 6 Addressing Architecture”

■RFC 2462: “IPv6 Stateless Address Autoconfiguration”

■RFC 3315: “Dynamic Host Configuration Protocol for IPv6 (DHCPv6)”

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