KB.15.15

Commands are executed in VLAN context.

• You must disable the DHCPv6 client before disabling DHCPv6 authentication.

• You must create a key chain with an ID and a duration before configuring DHCPv6 client

authentication with a key-chain name.

• The DHCPv6 client and DHCPv4 Relay can be enabled on the same interface and operate at

the same time.

Viewing configured DHCPv6 addresses

To view the current IPv6 DHCPv6 settings per-VLAN, use show run.

To view all currently configured IPv6 unicast addresses, use the following:

• show ipv6 (Lists IPv6 addresses for all VLANs configured on the switch.)

• show ipv6 vlan vid (Lists IPv6 addresses configured on the VLAN.)

General operating notes for DHCPv6

• If multiple DHCPv6 servers are available, the switch selects a server based on the preference

value sent in DHCPv6 messages from the servers.

• The switch supports both DHCPv4 and DHCPv6 client operation on the same VLAN.

• With IPv6 enabled, the switch determines the default IPv6 router for the VLAN from the RAs

it receives. See “Default IPv6 router” (page 35).

• DHCPv6 and statically configured global unicast addresses are mutually exclusive on a given

VLAN. That is, configuring DHCPv6 on a VLAN erases any static global unicast addresses

previously configured on that VLAN, and the reverse. (A statically configured link-local address

is not affected by configuring DHCPv6 on the VLAN.)

• For the same subnet on the switch, a DHCPv6 global unicast address assignment takes

precedence over an autoconfigured address assignment, regardless of which address type

was the first to be configured. If DHCPv6 is subsequently removed from the configuration, an

autoconfigured address assignment replaces it after the next RA is received on the VLAN.

DHCPv6 and autoconfigured addresses co-exist on the same VLAN if they belong to different

subnets.

For related information see:

• RFC 3315: "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)"

• RFC 3633: "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6"

• RFC 3736: "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6"

Statically configuring a link-local unicast address

Syntax:

[no] ipv6 address fe80::interface-id link-local

• If IPv6 is not already enabled on the VLAN, this command enables IPv6 and

configures a static link-local address.

• If IPv6 is already enabled on the VLAN, this command overwrites the current,

link-local address with the specified static address. (One link-local address is

allowed per VLAN interface.)

interface-id

The low-order 64 bits, in 16-bit blocks, comprise this value in a link-local address:

xxxx xxxx : xxxx xxxx : xxxx xxxx : xxxx xxxx

18 IPv6 Addressing Configuration