ipv6 dhcp server [pool-name]
Activates DHCPv6 server functionality on an interface using a configured pool.
ipv6 dhcp server <pool-name>When to Use This Command
- Serving IPv6 addresses to LAN hosts from a router acting as DHCPv6 server.
- Enabling stateful DHCPv6 on a gateway interface.
- Providing stateless DHCPv6 (DNS/domain only) when combined with SLAAC.
- Required step after creating an 'ipv6 dhcp pool'.
Command Examples
Enable DHCPv6 server on LAN interface
R1(config)# interface GigabitEthernet0/1
R1(config-if)# ipv6 address 2001:db8:1::1/64
R1(config-if)# ipv6 dhcp server IPV6-CLIENTS
R1(config-if)# ipv6 nd managed-config-flagR1(config-if)#
The interface now serves DHCPv6 addresses from the IPV6-CLIENTS pool. The M flag tells clients to request an address from DHCPv6 instead of or in addition to SLAAC.
Verify active DHCPv6 server
R1# show ipv6 dhcp interface GigabitEthernet0/1GigabitEthernet0/1 is in server mode Using pool: IPV6-CLIENTS Preference value: 0 Hint from client: ignored Rapid-Commit: disabled
Confirms the interface is in server mode using the IPV6-CLIENTS pool. Preference 0 is the default (used for server selection when multiple DHCPv6 servers exist).
Understanding the Output
Verify with 'show ipv6 dhcp interface [intf]' to confirm server mode and pool. Use 'show ipv6 dhcp binding' to see active leases. If no clients appear in the binding table, check that the M or O flag is set on the interface and that clients are sending DHCPv6 Solicit messages.
CCNA Exam Tips
CCNA exam tip: 'ipv6 dhcp server' is configured per-interface, not globally. Each interface that serves clients needs this command.
CCNA exam tip: DHCPv6 uses UDP port 546 (client) and 547 (server) — different from IPv4 DHCP (67/68).
CCNA exam tip: For stateless DHCPv6 (DNS only, addresses from SLAAC), use the O flag but NOT the M flag.
CCNA exam tip: 'show ipv6 dhcp interface' and 'show ipv6 dhcp pool' are the two key verification commands.
Common Mistakes
Mistake 1: Referencing a pool name that doesn't exist or has a typo — no addresses are served.
Mistake 2: Forgetting to set the M or O flag on the interface — hosts fall back to SLAAC only.
Mistake 3: Configuring DHCPv6 server without configuring an IPv6 address on the interface — DHCPv6 requires the interface to be IPv6-enabled.
Related Commands
ipv6 dhcp pool [name]
Creates a DHCPv6 server pool and enters DHCPv6 pool configuration mode. Used to configure stateful DHCPv6, where the server assigns IPv6 addresses and provides DNS/domain information to clients.
ipv6 nd managed-config-flag
Sets the Managed (M) flag in IPv6 Router Advertisement (RA) messages sent from this interface. When M=1, clients are instructed to obtain their IPv6 address from a DHCPv6 server (stateful DHCPv6) rather than using SLAAC.
show ipv6 dhcp binding
Displays active DHCPv6 address bindings — the list of IPv6 addresses that have been leased from the DHCPv6 server along with the client DUID (Device Unique Identifier), IAID, and lease expiry times.
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