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Campus DHCP Service Frequently Asked Questions Locating your device's hardware addressDHCP Service Information
DHCP Registration Information
Dynamic DNS with DHCP Information
Requesting Service / Contacting the Campus Hostmaster
DHCP Troubleshooting Information
What's the hardware address and how do I find it on my device? The hardware address is the Media Access Control (or MAC) address that uniquely identifies the network interface in your device. Your device may have more than one network interface; be sure you identify the address of the wired interface connected to the campus network. The address is a 6-byte hexadecimal number. Each digit can be either a number from 0-9 or a letter from A-F (letters are case-insensitive). The address is sometimes separated by dashes or colons (e.g., 00-80-C7-CF-83-A2, 00:80:c7:cf:83:a2). On PC's, the hardware address is sometimes called the Ethernet Adapter Address or Physical Address. If you have a modem card installed, that, too, will have an adapter address, but it isn't the one you need to register for DHCP. If you see an Adapter Address that starts "44-45-53..." you are looking at the modem's adapter address. You need the address associated with the ethernet adapter. More information on locating your device's hardware address may be found at the Student Computer Consulting Service website on their Documentation page. The Office of Residential Computing also has a guide titled Finding Your Ethernet Card Address. Who's eligible to use the campus DHCP service? Faculty, staff, and registered UC Berkeley students are eligible. Summer-school only and University Extension students are not eligible. An exception is a summer school student who is also admitted to attend the University during the academic year.
Where can I use the campus DHCP service? The campus DHCP service is available on any subnet supported by IST. The campus DHCP service is also available on subnets designated as private networks where the subnet terminates on an IST managed router. To find out if your subnet is set up for DHCP service, see your departmental network contact or send email to the campus Hostmaster.
When I use the campus DHCP service, I get an IP address with a hostname in the subdomain LIPS.Berkeley.EDU. Why? The campus DHCP service will issue a lease for an IP address from a dynamic pool to any registered device. For this reason, it does not make sense to use departmental, or other specific subdomains for the DNS records of IP addresses in dynamic pools. The LIPS.Berkeley.EDU subdomain is used as a general container for DNS records for all IP addresses in dynamic pools, just like AirBears.Berkeley.EDU is used as a container for IP addresses used by AirBears clients. The campus DHCP service used to be called the Laptop IP Service, hence the subdomain LIPS.Berkeley.EDU. Fixed assignment of an IP address is generally restricted to one MAC address (and therefore one device). In this case, a departmental or other specific subdomain is used wherever possible for the associated DNS. Upon request, an existing or new hostname may be used instead of a default identifier. Contact the campus Hostmaster for DNS requests and questions related to fixed assignment of IP addresses via DHCP.
Doesn't AirBears use DHCP? Is DHCP a form of network authentication? Is there any relation between the campus DHCP service and AirBears? AirBears uses DHCP to assign IP addresses and other network configuration information to wireless clients. Unlike the campus DHCP service used with the wired network, AirBears does not require registration of MAC addresses. The DHCP servers hand out a DHCP lease to any AirBears client requesting one (provided there are addresses available). Since wireless signals are not confined to a space that may be physically secured (they often leak outside of buildings, for example), the AirBears network uses a captive portal access control system to authenticate access to the wireless network. For the campus wired network, access control has traditionally been based on the physical security of the space containing the network connection. The DHCP registration process is not an authentication mechanism; DHCP itself was not designed with any access control or authentication features. (Some such features have been proposed, but are not yet widely implemented by vendors; see RFC 3118) The registration mechanism allows the association of attributes (such as a dynamic hostname or fixed IP address) to individual computers and records a contact for the device should it cause network or security problems. The same DHCP servers are used with AirBears and the campus DHCP service. The servers are configured to handle DHCP requests differently depending on which type of network (wireless vs. wired) the request is originated from.
Can I register more than one device? Yes. Each device you register must be used for official campus business or your own personal use. You may register devices for which you coordinate or provide IT support, as part of your University employment, but are not the primary user. Please be aware that you will be the point of contact regarding security or other problems related to each device you register. If you register devices other than your own please keep an inventory of these devices so that you may quickly respond to questions regarding them.
I just registered, but I didn't get any confirmation about when I could start using DHCP? No confirmation mail is sent. You may use DHCP immediately after successfully registering your device's MAC address via the registration application.
Why does the registration page say that my hardware address is already registered? The ethernet hardware address is a unique identification number built into each network interface. Chances are that the address you are attempting to register is already registered. Contact the campus Hostmaster to update the registration information for the address. An address that begins "44-45-53..." is not an ethernet address, but is a pseudo-address for the modem card. In all likelihood, when you were in the 'winipcfg' configuration, you had "PPP Adapter" highlighted in the window. You need to click on the pull-down tab and make sure the ethernet card is shown in the window.
My department has a DHCP server and I've already registered my device with them, do I need to re-register to use the campus DHCP service? Yes, you will have to register separately to use the campus DHCP service.
I have a static IP address for my office connection; does that mean I have to reconfigure my device whenever I move between my office connection and a connection on a different subnet using DHCP? No. Speak with your departmental network contact (or the campus Hostmaster directly) to convert the static IP address assigned to your office connection to a fixed IP address assignment via DHCP.
You may register virtual addresses associated with virtual machines provided you follow these guidelines to avoid conflicts. First, make sure that the virtual hardware (or MAC) address you intend to use will not conflict with any address that may be assigned to hardware by a manufacturer. Since addresses assigned to hardware may not be modifiable, virtual machines must avoid potential conflicts with hardware when selecting an address. Determine if your virtual environment assigns addresses from a pool with one or more assigned OUIs. The OUI is the first three bytes in the address. For example, the OUI of the address 00:de:ad:be:ef:00 is 00-de-ad. You can look up OUI assignments on the IEEE website http://standards.ieee.org/regauth/oui/index.shtml. Check with the listed entity to ensure that the OUI is for use by virtual machines. For example, the Xen hypervisor has the assigned OUI 00-16-3e that is designated for use by virtual machines per a Xen website: http://wiki.xensource.com/xenwiki/XenNetworking#head-d5446face7e308f577e5aee1c72cf9d156903722 If your virtual environment does not have a pool of addresses for assignment to virtual machines, you will need to create your own pool. To do this, choose an address from one of the hardware addresses associated with the server that hosts your virtual environment. Convert the first byte of the address to binary, set the second most least significant bit to one, and convert the resulting binary value back to hex. This operation converts the hardware address into a locally administered address. If you need additional addresses, increment this initial address as needed to obtain more addresses. For example, if 00:de:ad:be:ef:00 is a hardware address, the locally assigned address is 02:de:ad:be:ef:00. The next locally assigned address is 02:de:ad:be:ef:01. Once you've determined the MAC address you will use with your virtual machine, register the address with the campus DHCP service. If you registration succeeds (the address is not already in use by someone else) you may use the address. Take whatever steps are required in your virtual environment to ensure that the MAC address does not change in the future. If your registration did not succeed because the address was already registered, based on the information gathered previously generate a new address and attempt to register it. Is dynamic DNS available without the use of DHCP? No. Dynamic updates to the DNS are only available via the campus DHCP service.
Are client initiated updates to dynamic DNS allowed? No. Dynamic updates to the DNS are only available via the campus DHCP service.
Are dynamic DNS hostnames allowed in subdomains other than dyn.Berkeley.EDU? No. All hostnames used in the dynamic DNS service must be in the dyn.Berkeley.EDU subdomain.
Are CNAME and MX records referring to Dynamic DNS hostnames allowed? No. Such records create inconsistencies in the DNS when the hostnames they refer to are not present in the DNS.
How do I contact the campus Hostmaster? The campus Hostmaster may be reached at the email address hostmaster@nic.Berkeley.EDU. For more information on the campus Hostmaster service please see the website http://www.net.berkeley.edu/hostmaster/.
How do I determine the static assignment of an IP address associated with a network connection? The campus Hostmaster maintains records of static assignment of IP addresses to network connections identified by cable id. Before asking Hostmaster for the IP address and related information for a particular network connection, determine the cable id of the connection (usually found on the wall box or outlet). Send an email to hostmaster@nic.Berkeley.EDU requesting the IP address and related information for the cable id. Here is an example request. From: Phillip "Edward" Nunez <phillip@CSUA.Berkeley.EDU> To: UCB Hostmaster <hostmaster@nic.Berkeley.EDU> Subject: Static IP address assignment for cable id S2484-113-S204-002-D Greetings Hostmaster, Please respond with the IP address and related information required to configure a device to operate on the network for cable id S2484-113-S204-002-D. Thanks Phillip
How do I request a fixed assignment of an IP address for a device? To request fixed assignment of an IP address via DHCP for a device, first look up the device's hardware address for the interface connected to the wired network. Register this address if you have not already done so. Determine the cable id for the network connection the device is connected to. If the device currently has an IP address (either via DHCP or manually configured based on a static assignment from the campus Hostmaster), make a note of this address. Send an email to hostmaster@nic.Berkeley.EDU requesting a fixed assignment along with all of this information. Here is an example request. From: Phillip "Edward" Nunez <phillip@CSUA.Berkeley.EDU> To: UCB Hostmaster <hostmaster@nic.Berkeley.EDU> Subject: Fixed IP address assignment for 00:00:DE:AD:BE:EF Greetings Hostmaster, Please assign an IP address to the hardware address 00:00:DE:AD:BE:EF. The device with this address is using cable id S2484-113-S204-002-D and IP address 169.229.209.97 assigned via DHCP. Thanks Phillip If you would like an existing static assignment converted to a fixed assignment, specify the IP address of the static assignment you wish to convert in the request. Include any DNS changes in your request as well.
How do I request a dynamic DNS hostname for a device? To request a dynamic DNS hostname for a device, first look up the device's hardware address for the interface connected to the wired network. Register this address if you have not already done so. Send an email to hostmaster@nic.Berkeley.EDU requesting a dynamic DNS hostname along with the hardware address of the device. Here is an example request. From: Phillip "Edward" Nunez <phillip@CSUA.Berkeley.EDU> To: UCB Hostmaster <hostmaster@nic.Berkeley.EDU> Subject: Dynamic DNS hostname request for 00:00:DE:AD:BE:EF Greetings Hostmaster, Please assign the dynamic DNS hostname sirloin.dyn.Berkeley.EDU to the hardware address 00:00:DE:AD:BE:EF. Thanks Phillip Note that the subdomain for all dynamic DNS hostnames is dyn.Berkeley.EDU.
How do I request a pool of dynamic IP addresses for a subnet? To request a pool of dynamic IP addresses for a subnet, first determine the cable ids of the network connections you wish to convert to DHCP. Send the list of cable ids in an email to hostmaster@nic.Berkeley.EDU. Let hostmaster know which of these connections are currently active. Here is an example request. From: Phillip "Edward" Nunez <phillip@CSUA.Berkeley.EDU> To: UCB Hostmaster <hostmaster@nic.Berkeley.EDU> Subject: DHCP Dynamic IP pool request Greetings Hostmaster, I wish to establish a dynamic pool of IP addresses for use on the following cable ids, none of which are currently in use by a network device. All of these cables are active. S2484-113-S204-002-D S2484-113-S204-003-D S2484-113-S204-004-D S2484-113-S204-005-D S2484-113-S204-006-D S2484-113-S204-007-D Thanks Phillip Note that the subdomain for all dynamic DNS hostnames is dyn.Berkeley.EDU.
I've configured my device to obtain an IP address using DHCP, but I still can't connect to the network. What am I doing wrong? If your registration is active, you may want to verify that your wired network interface is working correctly (particularly if this is the first time you're using it), by trying to configure it with a static IP address. If you are faculty or staff, try checking with your departmental support group for assistance. No central support is available for device configuration; the Departmental On-site Computing Support (DOCS) service is available on a contract basis for device support for faculty and staff. Students may contact the Student Computer Consulting Service for support. Correctly configured and registered devices that experience problems with the DHCP service should be reported to the IST Service Desk as a network problem.
Where can I go for help? Students residing in one of the campus Residence Halls should contact the Rescomp help desk for configuration issues. No central support is available for device configuration; the Departmental On-site Computing Support (DOCS) service is available on a contract basis for device support for faculty and staff. Students may contact the Student Computer Consulting Service for support.
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Contact hostmaster@nic.berkeley.edu for more information. |