DHCPv6 prefix delegation ======================== | DHCPv6 prefix delegation client implementation is split between Control Plane and Data Plane. | Data Plane can also be used alone by external application (external Control Plane) using Data Plane Binary API. | Number of different IA_PDs managed by VPP is currently limited to 1 (and corresponding IAID has value 1). | Client ID is of type DUID-LLT (Link Layer address plus time) and is created on VPP startup from avaliable interfaces (or chosen at random for debugging purposes). | Server ID is only visible to Data Plane. Control Plane identifies servers by a 32-bit handle (server_index) mapped to Server ID by Data Plane. Control Plane ------------- | DHCPv6 PD clients are configured per interface. | When configuring a PD client we have to choose a name of a prefix group for that client. | Each prefix obtained through this client will be flagged as belonging to specified prefix group. | The prefix groups are used as a filter by prefix consumers. | To enable client on particular interface call Binary API function dhcp6_pd_client_enable_disable with param ‘sw_if_index’ set to that interface, ‘prefix_group’ set to prefix group name and ‘enable’ set to true. | Format of corresponding Debug CLI command is: “dhcp6 pd client [disable]” To add/delete IPv6 address potentially using available prefix from specified prefix group call Binary API command ip6_add_del_address_using_prefix with parameters: > sw_if_index - software interface index of interface to add/delete address to/from > prefix_group - name of prefix group, prefix_group[0] == ‘\\0’ means no prefix should be used > address - address or suffix to be used with a prefix from selected group > prefix_length - subnet prefix for the address > is_add - 1 for add, 0 for remove or Debug CLI command with format: “set ip6 addresses [prefix group ] .. raw:: html
[del]” | When no prefix is avaliable, no address is physically added, but is added once a prefix becomes avaliable. | Address is removed when all available prefixes are removed. | When a used prefix is removed and there is other available prefix, the address that used the prefix is reconfigured using the available prefix. | There are three debug CLI commands (with no parameters) used to show the state of clients, prefixes and addresses: | show ip6 pd clients | show ip6 prefixes | show ip6 addresses Example configuration ~~~~~~~~~~~~~~~~~~~~~ set int state GigabitEthernet0/8/0 up dhcp6 pd client GigabitEthernet0/8/0 prefix group my-dhcp6-pd-group set ip6 address GigabitEthernet0/8/0 prefix group my-dhcp6-pd-group ::7/64 Data Plane ---------- | First API message to be called is dhcp6_clients_enable_disable with enable parameter set to 1. | It enables DHCPv6 client subsystem to receive UDP messages containing DHCPv6 client port (sets the router to DHCPv6 client mode). | This is to ensure client subsystem gets the messages instead of DHCPv6 proxy subsystem. | There is one common Binary API call for sending DHCPv6 client messages (dhcp6_pd_send_client_message) with these fields: | > msg_type - message type (e.g. Solicit) > sw_if_index - index of TX interface > server_index - used to dentify DHCPv6 server, unique for each DHCPv6 server on the link, value obrtained from dhcp6_pd_reply_event API message, use ~0 to send message to all DHCPv6 servers > param irt - initial retransmission time > param mrt - maximum retransmission time > param mrc - maximum retransmission count > param mrd - maximum retransmission duration for sending the message > stop - if non-zero then stop resending the message, otherwise start sending the message > T1 - value of T1 in IA_PD option > T2 - value of T2 in IA_PD option > prefixes - list of prefixes in IA_PD option | The message is automatically resent by Data Plane based on parameters ‘irt’, ‘mrt’, ‘mrc’ and ‘mrd’. | To stop the resending call the same function (same msg_type is sufficient) with ‘stop’ set to 1. | To subscribe for notifications of DHCPv6 messages from server call Binary API function | want_dhcp6_pd_reply_events with enable_disable set to 1 | Notification (dhcp6_pd_reply_event) fileds are: | > sw_if_index - index of RX interface > server_index - used to dentify DHCPv6 server, unique for each DHCPv6 server on the link > msg_type - message type > T1 - value of T1 in IA_PD option > T2 - value of T2 in IA_PD option > inner_status_code - value of status code inside IA_PD option > status_code - value of status code > preference - value of preference option in reply message > prefixes - list of prefixes in IA_PD option | Prefix is a struct with with these fields: | > prefix - prefix bytes > prefix_length - prefix length > valid_time - valid lifetime > preferred_time - preferred lifetime