Viewing DHCP client information

To view DHCP client authentication or statistical information, enter the show dhcpv6 client command with the appropriate option. To view information about a specific VLAN, enter the vlan command with the VLAN name or identifier.

Syntax:

show ipv6 dhcp-client [ authentication [ vlan vid ] | statistics [ vlan vid ] ]

Displays information about IPv6 DHCP client authentication parameters or DHCP client statistics.

authentication

Displays authentication information such as enabled or disabled, mode, key-chain, and key-id

statistics

Displays information such as transmitted packets, received packets, and authentication failures.

DHCP client authentication show command for all VLANs

show ipv6 dhcp-client authentication
DHCPv6 Authentication Information
 
 Vlan Name             : DEFAULT_VLAN
 Authentication        : Enabled
 Authentication mode   : HMAC-MD5
 Key-Chain             : DHCP10
 Key-Id                : 1
 
 Vlan Name             : VLAN2
 Authentication        : Enabled
 Authentication mode   : HMAC-MD5
 Key-Chain             : DHCP10
 Key-Id                  : 1

DHCP client authentication show command for a specific VLAN

show ipv6 dhcp-client authentication vlan 1

DHCPv6 Authentication Information

 Vlan Name             : DEFAULT_VLAN
 Authentication        : Enabled
 Authentication Mode   : HMAC-MD5
 Key-Chain             : DHCP10

DHCP client statistics for all VLANs

show ipv6 dhcp-client statistics
DHCPv6 Statistics Information

 Vlan Name               : DEFAULT_VLAN
 Transmitted Packets     : 10000
 Received Packets        : 9998
 Authentication Failures : 2

 Vlan Name               : VLAN2
 Transmitted Packets     : 5000
 Received Packets        : 3500
 Authentication Failures : 0

DHCP client statistics for a single VLAN

show ipv6 dhcp-client statistics vlan 1
DHCPv6 Statistics Information

 Vlan Name               : DEFAULT_VLAN
 Transmitted Packets     : 10000
 Received Packets        : 9998
 Authentication Failures : 2

DHCPv6 client authentication operating notes

The DHCPv6 client must be stopped before setting the authentication mode or entering a key-chain name. Use the no ipv6 address dhcp full command to disable DHCPv6. 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 commands:

Syntax

show ipv6

Lists IPv6 addresses for all VLANs configured on the switch.

Syntax

show ipv6 vlan vid

Lists IPv6 addresses configured on the VLAN.

DHCPv6 operating notes

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.
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.
With IPv6 enabled, the switch determines the default IPv6 router for the VLAN from the RAs it receives. See View IPv6 gateway, route, and router neighbors.
If DHCPv6 is configured on a VLAN, configuring a static global unicast address on the VLAN removes DHCPv6 from the VLAN's configuration and deletes the DHCPv6-assigned global unicast address.
For a statically configured global unicast address to be routable, a gateway router must be transmitting RAs on the VLAN.
If an autoconfigured global unicast address already exists for the same subnet as a new, statically configured global unicast address, the statically configured address is denied. In the reverse case, you can add an autoconfig command to the VLAN configuration, but it is not implemented unless the static address is removed from the configuration.

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"

authentication	Displays authentication information such as enabled or disabled, mode, key-chain, and key-id
statistics	Displays information such as transmitted packets, received packets, and authentication failures.

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