OIT Networking & Monitoring Services


[This document describes a field in the Princeton University Host Database. You may also view descriptions of other fields.]

The optional BOOTP-PARAMETERS (a.k.a. ADDITIONAL-BOOTP-PARAMS) field may be used to provide additional information to OIT DHCP and BootP Services. Unless you know exactly what you are doing, you should leave this field empty.

Strings entered in this field will be used by OIT DHCP and BootP Services when responding to DHCP and BootP equests from your device, when the response is for an IP address that appears in your device's Host Database entry. Normally those services respond as described in OIT DHCP and DHCP Services. If you need those services to provide additional values to your client, you specify them here, using the syntax required by OIT DHCP and DHCP Services.

When OIT DHCP Service respond to your device to lease your device an IP address that is not in your device's Host Database entry (for example, because your device is using not using OIT Static IP Service), information in this field is not used. That's because the values in this field are associated with the OIT Static IP addresses assigned to your device, not with your device's hardware addresses. E.g. if you were to specify special DNS servers in this field, then when your device is using the OIT Static IP addresses in its Host Database entry, OIT DHCP and DHCP Services will provide your device with the special DNS servers you specify. When your device is using another IP address (for example, an OIT Mobile Address), OIT DHCP Service will provide your device with the DNS servers associated with the IP address it leases to your device.

The string you specify should contain no spaces, except if spaces are required within the value of one of the tags you specify. Fields must be colon-delimited, and there should be no leading colon.

If you enter a value in this field, it completely replaces any previous value for the BOOTP-PARAMETERS field. So if the field contains special settings for DNS servers and a TFTP server, and you wish to remove just the TFTP server, then change the field to specify the DNS servers but omit the TFTP server. To completely clear the BOOTP-PARAMETERS field, specify the value NONE.

For a description of the tags understood by OIT DHCP and DHCP Services, see the bootptab(5) manual page for CMU dhcpd version 3.3.7 with the PU patches applied. Note that the data is case-sensitive.

The Host Database provides only limited syntax checking on the value you specify; it does not duplicate all the parsing performed by our BootP/DHCP servers. Therefore, it is possible to enter some syntactically incorrect values into this Host Database field. If you do so, our BootP/DHCP servers will either ignore the value, or more likely, ignore the entire entry for your Host Database entry. (The latter would cause your device to stop receiving any BootP and DHCP service.) Therefore, be careful when completing this field, paying close attention to the manual page mentioned above.) If you do enter a value that is so incorrect as to be unparseable by our BootP/DHCP servers, OIT may contact you to ask you to correct the entry.

Before using this feature, you may wish to inspect your host's current entry in the bootptab file; on any OIT UNIX System, you may view /u/nocnoc/hostmaster/bootptab. Be sure to also review the contents of any templates that your entry inherits from (e.g. a subnet template). You should also have a basic familiarity with the BootP and DHCP protocols; see RFC 951, RFC 1534, RFC 1542, RFC 2131, RFC 2132, RFC 2241, RFC 2242, RFC 2485, RFC 2489.

For those tags you where where the value is an ASCII (string) value, the length of the value (not including any terminating colon) is restricted to 79 characters.

When parsing the values you specify in the BOOTP-PARAMETERS field, we provide the following special features:

Note that if the entry contains multiple interfaces which are eligible for BootP or DHCP service, then any BOOTP-PARAMETERS field you specify will affect all the interfaces. You cannot use the BOOTP-PARAMETERS field to specify values that should only apply to a single interface.

Because we cannot change the characteristics of a current (unexpired) DHCP lease, any change you make to the BOOTP-PARAMETERS field may not be reliably propagated to a DHCP client until any current DHCP lease for this client has been expired or been invalidated on all OIT DHCP servers. See DHCP and BootP Services: Forcing a DHCP Lease to Be Discarded.


The examples below are only to illustrate typical use of the BOOTP-PARAMETERS field; the specific values are only for illustrative purposes.

A service of OIT Networking & Monitoring Services
The Office of Information Technology,
Princeton University