OIT Networking & Monitoring Services

OIT Static IP Service

Note well that this service soon will retired as part of the Retirement of the Princeton University Host Database and Related Services.

OIT Static IP Service provides a static (unchanging) IP address and DNS hostname to your computer when it is attached to OIT Ethernet Service on its "home network."

A computer's "home network" is defined as the IP network (a.k.a. "subnet") specified in the computer's Princeton University Host Database entry. Some networks span multiple buildings; conversely, some buildings contain several networks. For a list of buildings and networks, see the Princeton Network ("subnet") List.

OIT Static IP Service is not available to clients using any of the following services: wireless services provided by OIT, and Visitor IP (VIP) Service.

If you have questions about the procedures below, or encounter difficulties related to them, please contact the OIT Support and Operations Center for assistance.

Contents

  1. General Procedures
  2. Requirements
  3. How Does it Work?
  4. Unused OIT Static IP Addresses Are Recycled
  5. Dormnet Subscriptions and OIT Static IP Service
  6. Multiple Interface Devices
  7. Related Resources
  8. If You Need Additional Assistance
  9. Announcements

General Procedures

The following procedures apply to all computers attached to the campus network:


Requirements

To use OIT Static IP service, your computer must meet the following requirements:


How Does it Work?

For devices meeting the requirements above, OIT Static IP service works as follows:

If you have configured your device to obtain its IP information manually

The device simply uses the IP configuration you entered. It does not rely on OIT BootP Service or OIT DHCP Service to learn its IP configuration.

Assuming you have correctly entered the IP configuration, the IP configuration will work as long as your device is attached to its "home network."

If you relocate your device to a network other than its "home network", this IP configuration will not work there.

If your device meets the eligibility requirements for OIT Mobile IP Service, it may instead use that service while visiting another network; you would need to reconfigure the device to obtain its IP configuration via DHCP. If use of OIT Mobile IP Service is not feasible or desirable, to obtain IP service in the new location, you would need to update the Host Database entry to reflect the device's new "home network", and reconfigure your device with the new IP configuration, so you may use OIT Static IP Service while attached to that new network. (The latter approach is not feasible for a Dormnet subscription; by definition a Dormnet subscription's Ethernet interface is homed on either driftnet or pu-dormnet-bb (aka "Dormnet), and its Wireless interface (if any) is homed on the wirelessnet. The Ethernet interface's manual configuration will work only if the device's Ethernet interface is registered as homed on pu-dormnet-bb (not driftnet) and the device's Ethernet interface is attached via pu-dormnet-bb (a.k.a. Dormnet). Manual configuration of the wireless interface will not work anywhere.)

Manual configuration is not feasible for a device's network interface attached via any wireless services provided by OIT. The wirelessnet IP address that appears in devices' Host Database entries are simply placeholders; a device manually configured to use a wirelessnet IP address will not work.

Manual configuration is not feasible for a device's network interface that is registered in the Host Database as being homed on recyclenet. The recyclenet IP address that appears in the device's Host Database entry is simply a placeholder; a device manually configured to use a recyclenet IP address will not work. If you wish to use manual configuration, first change the Host Database entry to replace the recyclenet IP address with one on the network to which the device is actually attached.

Manual configuration is not feasible for a device's network interface that is registered in the Host Database as being homed on driftnet. The drifnet IP address that appears in the device's Host Database entry is simply a placeholder; a device manually configured to use a drifnet IP address will not work. If you wish to use manual configuration, first change the Host Database entry to replace the driftnet IP address with one on the network to which the device is actually attached.

Before manually configuring a device to use an IP address, be sure that the IP address you manually configure is indeed the IP address assigned in the Host Database for this device to use. You may View the Host Database to double-check.

Before manually configuring a device to use an IP address, be sure that the IP address you manually configure is indeed an OIT Static IP Address. You may check if an IP address is an OIT Static IP Address by using the Categorize IP Address tool.

If you have configured your device to obtain its IP information via BootP

The device uses OIT BootP Service to obtain its IP configuration. OIT BootP Service will provide an IP configuration to your device as long as it is attached to its "home network."

If you relocate your device to a network other than its "home network", OIT BootP Service will not provide it with an IP configuration.

If your device meets the eligibility requirements for OIT Mobile IP Service, it may instead use that service while visiting another network; you would need to reconfigure the device to obtain its IP configuration via DHCP. If use of OIT Mobile IP Service is not feasible or desirable, to obtain IP service in the new location, you would need to update the Host Database entry to reflect the device's new "home network", so you may use OIT Static IP Service while attached to that new network. (The latter approach is not feasible for a Dormnet subscription; by definition a Dormnet subscription's Ethernet interface is homed on either driftnet or pu-dormnet-bb (aka "Dormnet), and its Wireless interface (if any) is homed on the wirelessnet. The Ethernet interface's configuration to use BootP will work only if the device's Ethernet interface is registered as homed on pu-dormnet-bb (not driftnet) and the device's Ethernet interface is attached via pu-dormnet-bb (a.k.a. Dormnet). BootP configuration of the wireless interface will not work anywhere.)

BootP configuration is not feasible for a device's network interface attached via OIT Wireless Service. OIT Wireless Service relies on OIT Mobile IP Service, which in turn relies on DHCP (not BootP).

BootP configuration is not feasible for a device's network interface that is registered in the Host Database as being homed on recyclenet. If you wish to use BootP configuration, first change the Host Database entry to replace the recyclenet IP address with one on the network to which the device is actually attached.

BootP configuration is not feasible for a device's network interface that is registered in the Host Database as being homed on driftnet. If you wish to use BootP configuration, first change the Host Database entry to replace the driftnet IP address with one on the network to which the device is actually attached.

If you have configured your device to obtain its IP information via DHCP

The device uses OIT DHCP Service to obtain its IP configuration. While your device is attached to its "home network", OIT's DHCP servers assign ("lease") to the interface the static IP address and Internet hostname that appear in the Host Database for your computer.

If you relocate your device to a network other than its "home network", and if your device meets the eligibility requirements for OIT Mobile IP Service, it will use that service. OIT DHCP Servers will assign ("lease") to the interface an OIT Mobile IP address and Internet hostname, and provide your device with an appropriate IP configuration for the network it is visiting.


Unused OIT Static IP Addresses Are Recycled

While the University is fortunate to have a large number of IP addresses suitable for assignment as OIT Static IP Addresses, the number is still finite. If not actively managed, shortages can become an issue.

When an entry is deleted from the Host Database, any OIT Static IP Addresses in the entry are reclaimed by OIT:

Sometimes the Technical Contacts responsible for an office device forget to remove the entry from the Host Database after the device has been retired.

The OIT Static IP Recycling Facility (SIRF) detects when an OIT Static IP Address has not used on the campus network for a long time. It recycles those IP addresses, so they may be re-assigned. This helps the University preserve a supply of IP addresses.


Dormnet Subscriptions and OIT Static IP Service

When a new Host Database entry is created for a Dormnet subscription (a.k.a. a "Dormnet Host Database entry"), it is created with no IP addresses.

When a Dormnet Host Database entry is subscribed, the first network interface (the interface identified in the Host Database as the device's "Ethernet" interface) is assigned an IP address. The subscription form requires the customer to select among the following choices for this network interface:

If the customer accepts the default Always rely on OIT Mobile IP Service (usually recommended), the first network interface is assigned an IP address on driftnet. The device's Ethernet interface will rely on OIT Mobile IP Service when it is attached to the pu-dormnet-bb network (the network used for OIT Ethernet Service in dormitories, apartments, and eating clubs), and when it is attached via OIT Ethernet Service in other locations. It will not rely on OIT Static IP Service in any location.

If the customer instead chooses Rely on OIT Static IP Service on pu-dormnet-bb; rely on OIT Mobile IP Service elsewhere, the first network interface is assigned an OIT Static IP address on pu-dormnet-bb. The device's Ethernet interface will rely on OIT Static IP Service when it is attached to the pu-dormnet-bb network (the network used for OIT Ethernet Service in dormitories, apartments, and eating clubs). When the device's Ethernet interface is attached to any other network, it will rely on OIT Mobile IP Service.

The form used by a customer to Change a Dormnet Entry may also be used at a later time to change the first network interface in the entry between these two choices. (The choice made at subscription time can be changed at a later date by the customer.)

A Dormnet subscription does not provide the ability to assign the device's first network interface an OIT Static IP Address on any other subnet; the only choices are driftnet and pu-dormnet-bb. This is because a Dormnet subscription is intended to provide service to personally-owned student devices.

Each Dormnet Host Database entry may optionally have one wireless interface registered as well. This is normally registered as the entry's second interface. The Host Database will assign this interface a wirelessnet IP address. This is not an OIT Static IP Address. It acts as a placeholder, indicating the network interface speaks IP, but has not OIT Static IP Address assigned. When the network interface is attached to the network, even to OIT Wireless Service, it will not receive OIT Static IP Service. (Assuming it is configured to obtain its IP address via DHCP, then when it is attached to a network where OIT Mobile IP Service is available, it uses OIT Mobile IP Service. When attached via OIT Wireless Service, the device's network interface receives an IP address (via DHCP) via an OIT-provided DHCP-based service that is presently undocumented; OIT Wireless Service does not use OIT Mobile IP Service.)

When a Host Database entry for a Dormnet subscription is unsubscribed, all IP addresses in the Host Database entry are removed from the entry. If the Host Database entry is later resubscribed to Dormnet, new IP address(es) are assigned.


Multiple Interface Devices

Our service supports devices with multiple network interfaces, for example, a computer with one Ethernet interface homed on one network, and another Ethernet interface homed on another network.

Each network interface that is eligible for OIT Static IP Service is treated separately. Each has its own "home network." Each is is independently eligible to use BootP or DHCP (if you choose to configure the interface to use either of those services).

Therefore, each such interface is independently eligible for Mobile IP Service. It is possible that one interface (attached to its home network) may be using OIT Static IP Service at the same time that the other interface (attached to a network other than its home network) may be using OIT Mobile IP Service.

If your device is assigned more than one IP address in the Host Database, then OIT inserts all of these IP addreses into DNS as belonging to your device's hostname. (One exception is that IP addresses on the wirelessnet network are never inserted into DNS, as they are only placeholders intended to indicate that the interface is registered for use with OIT Wireless Service.) A DNS lookup for the IP addressses associated with your device's hostname will return all of these IP addresses. A DNS lookup for the name associated with any of these IP addresses will return your device's canonical hostname.


Related Resources


If You Need Additional Assistance

If you have questions or need assistance with any of the procedures in this document, please contact the OIT Support and Operations Center.


Announcements


A service of OIT Networking & Monitoring Services
The Office of Information Technology,
Princeton University
Last Updated: January 14 2019