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    Deleting DHCPv6 Client Bindings

    The JunosE Software enables you to manage your router’s DHCPv6 local server client bindings. The client binding associates an IPv6 prefix with a unique DHCP ID (DUID) of the subscriber client. To view information about current DHCPv6 client bindings and track lease times of a specific client binding, use the show ipv6 dhcpv6–local binding command.

    To delete a client binding and the associated route configuration when the DHCPv6 client binding is no longer needed, use the dhcpv6 delete-binding command. You can delete the DHCPv6 client bindings instead of waiting for the lease timer to expire. Use the following keywords and variables with the dhcpv6 delete-binding command to specify (filter) the client bindings you want to delete:

    • all—All DHCPv6 local server client bindings
    • ipv6Prefix—IPv6 prefix (address and subnetwork mask) of the DHCPv6 clients; for example, 2002:2:4:1::/64
    • string—Local address pool name; for example, server4pool

    Note: After a stateful SRP switchover, in a scaled environment, the interface strings associated with DHCPv6 client bindings might not be displayed in the output of the show commands used to view information about client bindings if you issue the show command immediately after a stateful SRP switchover. These show commands display interface strings in the output only if the restoration of IPv6 interfaces on the router is complete after the SRP warm switchover. After the restoration of IPv6 interfaces is complete, interface strings are displayed properly in the output of the show commands available for this purpose.

    You can remove all DHCPv6 client bindings, all DHCPv6 client bindings of a particular type, or a specified DHCPv6 client binding that meets the deletion criteria you specify.

    • To delete all DHCPv6 client bindings on virtual router vr1:
      host1:vr1#dhcpv6 delete-binding all
    • To delete DHCPv6 client bindings with the specified IPv6 prefix:
      host1:vr1#dhcpv6 delete-binding 2002:2:4:1::/64
    • To delete a group of DHCPv6 client bindings that were assigned prefix from the local pool:
      host1:vr2#dhcpv6 delete-binding server4pool

    The router does not notify the DHCPv6 client when you use the dhcpv6 delete-binding command. To verify that the DHCPv6 client bindings have been deleted, use the show ipv6 dhcpv6–local binding command.

    In JunosE Release 11.3.0, when DHCPv6 client bindings are brought up over a PPPv6 session, on a router that acts as an L2TP network server (LNS) and is enabled for stateful line module switchover, the client bindings are removed when the primary line module fails and the spare line module takes over as the primary. This behavior occurs because the underlying dynamic IPv6 over PPP interface goes down temporarily (when the subscriber session is disrupted briefly) before the interface becomes operational again on the newly active primary module. When the dynamic IPv6 over PPP interface goes down temporarily (when the stateful switchover process is in progress), the DHCPv6 client binding and the access route for that interface are deleted. Similarly, DHCPv6 bindings are deleted when a PPP subscriber logs out and then back in. In such scenarios, the client needs to send a renew or rebind request to the DHCP server to enable the DHCPv6 binding to be re-created.

    Beginning with JunosE Release 12.0.0, DHCPv6 client bindings and access routes that are created over a PPPv6 session on an LNS device enabled for stateful line module switchover are retained when the dynamic IPv6 over PPP interface temporarily goes down during the stateful switchover operation. DHCPv6 client bindings and the associated route configuration are deleted only when the interface is deleted and not during the interface down event.

    DHCPv6 client bindings and access routes that are created over a PPPv6 session, on a router that acts as an LNS and is enabled for stateful line module switchover, are retained when the dynamic IPv6 over PPP interface goes down temporarily during the stateful switchover operation. When the stateful switchover procedure is complete, the interface is re-created on the newly active primary module and the DHCPv6 bindings are also retained. The same behavior of preservation of DHCPv6 bindings is applicable when a PPPv6 subscriber logs out and then back in.

    Published: 2014-08-20