HP IPv6 5400zl, IPv6 6200yl, IPv6 2900 Stateless Autoconfiguration of a Global Unicast Address

IPv6 Addressing

Global Unicast Address

Global Unicast Address

A global unicast address is required for unicast traffic to be routed across VLANs within an organization as well as across the public internet. To support subnetting, a VLAN can be configured with multiple global unicast addresses. Any of the following methods can be used to configure this kind of address on a VLAN:

■stateless address autoconfiguration using a prefix received in an adver- tisement received from a router on the VLAN (page 3-7)

■stateful address configuration using DHCPv6 (page 3-8)

■static address configuration (page 3-9)

Stateless Autoconfiguration of a Global Unicast

Address

If there is an IPv6-enabled router transmitting router advertisements on a VLAN interface, enabling this method generates a global, routable unicast address for the VLAN. The prefix for this address type is typically 64 bits with the three highest-order bits set to 2.

Router Advertisements. With autoconfiguration enabled, if the switch receives the same prefix from router advertisements (RAs) from multiple IPv6 routers on the same VLAN, then one global unicast address is configured with that prefix. If different prefixes are received from different routers on the same VLAN, then there will be one address configured on the VLAN for each unique prefix received. Where there are multiple routers on the VLAN, the default route for the VLAN is determined by the relative router priorities included in the RAs the VLAN receives. If the highest priority is duplicated on multiple routers, then the first RA detected on the VLAN determines the default route.

If the RA used to define the prefix for an autoconfigured address ceases to be received on the VLAN, then the address becomes deprecated. (Refer to “IPv6 Address Deprecation” on page 3-25.)

If IPv6 is not already enabled on a VLAN when you enable autoconfiguration on the VLAN, then the switch automatically generates a link-local address for the VLAN as well.

If IPv6 Is Not Already Enabled. Enabling address autoconfiguration on a VLAN when IPv6 is not already enabled on the VLAN causes the switch to:

3-16