Configuring the DHCPv6 Local Server

In addition to the embedded DHCP local server that is used for IP version 4 (IPv4) address support, E Series routers include an embedded DHCPv6 local server. This server enables the router to function as a server for the DHCP protocol for IP version 6 (IPv6). The DHCPv6 local server sends and receives packets via IPv6 and informs IPv6 of the routing requirements of the router clients.

The DHCPv6 local server provides the following IPv6 address support:

• Delegates IPv6 prefixes to client routers; each client can have one prefix; prefixes and DNS information can be locally configured or derived from RADIUS via AAA.
• Provides DNS server information to directly connected router clients.

  Note: You must add a vendor-specific attribute to RADIUS to enable E Series routers to retrieve IPv6 Domain Name System (DNS) addresses.

  Note: If an IPv6 prefix is not available to be delegated to requesting DHCPv6 clients, the delegating server sends the Identity Association for Prefix Delegation option, where each Identity Association for Prefix Delegation option consists of an Identity Association identifier and associated configuration information, in an Advertise message that includes a Status Code option containing the value NoPrefixAvail. For example, when a RADIUS server is used for authentication of DHCPv6 clients and the server is configured to disable the delegation of prefixes, in response to DHCPv6 Solicit messages that are received from the client, the server sends Identity Association for Prefix Delegation options in an Advertise message to the client.

  Note: If you configure the IPv6 prefix to be delegated to the client using RADIUS attributes and the client is authenticated by the RADIUS server, it is not necessary to configure the prefix associated with it using this procedure. In such a scenario, the prefix derives its settings from the Framed-IPv6-Prefix [23] or the Delegated-IPv6-Prefix [97] RADIUS IETF attributes.

Use the following steps to configure the DHCPv6 local server:

1. Enable the DHCPv6 local server.
   host1(config)#service dhcpv6-local
2. Specify the IPv6 prefix and lifetime that are to be delegated to the DHCPv6 client. The specified prefix is delegated by the DHCPv6 local server when requested by the client.
   host1(config-if)#ipv6 dhcpv6-local delegated-prefix 2001:db8:17::/48 lifetime infinite

   Use the lifetime keyword to specify the time period for which the prefix is valid. This lifetime overrides the default lifetime that is set in Global Configuration mode. If no lifetime is specified, the default lifetime is assigned.

   • Specify the number of days and, optionally, the number of hours, minutes, and seconds. You cannot specify a lifetime of zero (that is, you cannot set the days, hours, minutes, and seconds fields all to zero).
   • Use the keyword infinite to specify a lifetime that does not expire.
3. Specify the name of a DNS domain for DHCPv6 clients in the current virtual router to search. You can specify a maximum of four DNS domains for a DHCPv6 local server’s search list.
   host1(config)#ipv6 dhcpv6-local dns-domain-search xyzcorporation.com host1(config)#ipv6 dhcpv6-local dns-domain-search xyzcorp.com
4. Specify the IPv6 address of the DNS server and to assign the server to the DHCPv6 clients in the current virtual router. You can specify a maximum of four DNS servers.
   host1(config)#ipv6 dhcpv6-local dns-server 2001:db8:18::
5. Set the default lifetime for which a prefix delegated by this DHCPv6 local server is valid. This default is overridden by an interface-specific lifetime.
   host1(config)#ipv6 dhcpv6-local prefix-lifetime infinite
   • Specify the number of days and, optionally, the number of hours, minutes, and seconds. You cannot specify a lifetime of zero (that is, you cannot set the days, hours, minutes, and seconds fields all to zero).
   • Use the keyword infinite to specify a lifetime that does not expire.
6. Specify the DHCP unique identifier (DUID) type to be used in the communication between the DHCPv6 local server and clients. You can configure the type of DUID to be either Type 2 or Type 3. These two types are currently supported by the DHCPv6 local server application in JunosE Software. The Type 1 DUID is not supported by JunosE Software.
   host1(config)#ipv6 dhcpv6-local duid-type 3