DHCP Address Binding Notification Exit Program


  Required Parameter Group:

1 Request type Input Binary(4)
2 Client IP address Input Char(*)
3 Length of IP address Input Binary(4)
4 Client identifier Input Char(*)
5 Length of client identifier Input Binary(4)
6 Lease duration Input Binary(4)
7 Response packet Input Char(*)
8 Length of response packet Input Binary(4)

  Exit Point Name: QIBM_QTOD_DHCP_ABND

  Exit Point Format Name: DHCA0100

The DHCP Address Binding Notification exit program allows for notification each time the DHCP server assigns an IP address to a specific client host. This is known as address binding. The exit program will be called any time the DHCP server sends an acknowledgement packet (known as a DHCP ACK) to a DHCP client or sends a Bootstrap Protocol (BOOTP) reply packet to a BOOTP client. The two possible client IP address binding packets follow:

  1. A DHCP ACK from the server tells a DHCP client that it has been granted a lease to use a specific IP address for a specific period of time. Acknowledgements are sent when a DHCP client accepts an initial offer of an IP address made by the server, as well as each time that a DHCP client asks for the renewal of an existing IP address lease and the server grants it.

  2. A BOOTP reply packet is sent from the server in response to a BOOTP request packet from a client if the server decides to assign an IP address to that client. The BOOTP reply notifies the BOOTP client what IP address it has been assigned. Unlike DHCP, the BOOTP protocol does not support the concept of temporary leasing. Therefore, the address binding to the BOOTP client is considered permanent and there will be no ongoing exchange of renewal bindings. The DHCP server internally treats a BOOTP client binding as an infinite lease.

When an exit program is added to the exit point, it is called immediately after the DHCP server has transmitted one of the client IP address binding packets described above. This is for notification purposes only, and no data is expected to be sent back to the DHCP server from the exit program. The exit program will be sent information about the protocol type (DHCP or BOOTP), the identity of the client, the IP address, and the duration of the lease. In addition, a copy of the actual packet that was transmitted will be sent.

Note: Since this is an exit point of the DHCP server, the exit program can only be used to obtain notification of address bindings for the BOOTP client if the DHCP server is running. It cannot be used to obtain notification of IP address assignments for the BOOTP client made by the iSeries BOOTP server.


Authorities and Locks

None.


Required Parameter Group

Request type
INPUT; BINARY(4)

The type of request protocol being used between the client and server. The possible values are:

1 DHCP
2 BOOTP

Client IP address
INPUT; CHAR(*)

The Internet Protocol (IP) address that was bound to the client host. This string is in dotted decimal format and left-justified.

Length of client IP address
INPUT; BINARY(4)

The length (in bytes) of the client IP address.

Client identifier
INPUT; CHAR(*)

The unique identifier of the client that the IP address has been bound to. This is usually the hardware address of the client machine.

Length of client identifier
INPUT; BINARY(4)

The length (in bytes) of the client identifier string.

Lease duration
INPUT; BINARY(4)

The duration (in seconds) of the lease period for which the client may now use the IP address.

This field should be treated as a 32-bit unsigned number. The special value follows:

hex FFFFFFFF If all 32 bits are set to 1, this indicates that the lease is an infinite lease, which does not expire.

Response packet
INPUT; CHAR(*)

This is the DHCP or BOOTP message response packet that was transmitted from the DHCP server to the client host just prior to this notification exit program being called.

The formats of the packets are defined and maintained by the Internet Engineering Task Force (IETF) standards body. Refer to the following IETF Request For Comments (RFC) documents for the specifications:

Note: Since the packet is presented to the exit program just as it was transmitted on the network, it should be noted that any data areas of the packet that are defined as type string or character by the RFCs will be US-ASCII. On the iSeries, it is recommended that this data be treated as CCSID 819.

Length of response packet
INPUT; BINARY(4)

The length (in bytes) of the response packet.


Exit program introduced: V4R2
Top | Server Support APIs | APIs by category