How DHCP works for the DLINK DIR615 wireless router – Information valid for any DHCP server


Your wireless router works as the DHCP server by default. This is a good explanantion on how the DLINK Wireless router (DWR) can be configured for DHCP.

source: DLINK help on the DLink web interface screen

DHCP Server Settings
DHCP stands for Dynamic Host Configuration Protocol. The DHCP section is where you configure the built-in DHCP Server to assign IP addresses to the computers and other devices on your local area network (LAN).

Enable DHCP Server
Once your D-Link router is properly configured and this option is enabled, the DHCP Server will manage the IP addresses and other network configuration information for computers and other devices connected to your Local Area Network. There is no need for you to do this yourself.

The computers (and other devices) connected to your LAN also need to have their TCP/IP configuration set to “DHCP” or “Obtain an IP address automatically”.

When you set Enable DHCP Server, the following options are displayed.

DHCP IP Address Range
These two IP values (from and to) define a range of IP addresses that the DHCP Server uses when assigning addresses to computers and devices on your Local Area Network. Any addresses that are outside of this range are not managed by the DHCP Server; these could, therefore, be used for manually configured devices or devices that cannot use DHCP to obtain network address details automatically.
It is possible for a computer or device that is manually configured to have an address that does reside within this range. In this case the address should be reserved (see DHCP Reservation below), so that the DHCP Server knows that this specific address can only be used by a specific computer or device.

Your D-Link router, by default, has a static IP address of 192.168.0.1. This means that addresses 192.168.0.2 to 192.168.0.254 can be made available for allocation by the DHCP Server.

Example:
Your D-Link router uses 192.168.0.1 for the IP address. You’ve assigned a computer that you want to designate as a Web server with a static IP address of 192.168.0.3. You’ve assigned another computer that you want to designate as an FTP server with a static IP address of 192.168.0.4. Therefore the starting IP address for your DHCP IP address range needs to be 192.168.0.5 or greater.
Example:
Suppose you configure the DHCP Server to manage addresses From 192.168.0.100 To 192.168.0.199. This means that 192.168.0.3 to 192.168.0.99 and 192.168.0.200 to 192.168.0.254 are NOT managed by the DHCP Server. Computers or devices that use addresses from these ranges are to be manually configured. Suppose you have a web server computer that has a manually configured address of 192.168.0.100. Because this falls within the “managed range” be sure to create a reservation for this address and match it to the relevant computer (see Static DHCP Client below).
DHCP Lease Time
The amount of time that a computer may have an IP address before it is required to renew the lease. The lease functions just as a lease on an apartment would. The initial lease designates the amount of time before the lease expires. If the tenant wishes to retain the address when the lease is expired then a new lease is established. If the lease expires and the address is no longer needed than another tenant may use the address.
Always Broadcast
If all the computers on the LAN successfully obtain their IP addresses from the router’s DHCP server as expected, this option can remain disabled. However, if one of the computers on the LAN fails to obtain an IP address from the router’s DHCP server, it may have an old DHCP client that incorrectly turns off the broadcast flag of DHCP packets. Enabling this option will cause the router to always broadcast its responses to all clients, thereby working around the problem, at the cost of increased broadcast traffic on the LAN.
NetBIOS Advertisement
Check this box to allow the DHCP Server to offer NetBIOS configuration settings to the LAN hosts. NetBIOS allow LAN hosts to discover all other computers within the network, e.g. within Network Neighbourhood.
Learn NetBIOS information from WAN
If NetBIOS advertisement is swicthed on, switching this setting on causes WINS information to be learned from the WAN side, if available. Turn this setting off to configure manually.
Primary WINS Server IP address
Configure the IP address of the preferred WINS server. WINS Servers store information regarding network hosts, allowing hosts to ‘register’ themselves as well as discover other available hosts, e.g. for use in Network Neighbourhood. This setting has no effect if the ‘Learn NetBIOS information from WAN’ is activated.
Secondary WINS Server IP address
Configure the IP address of the backup WINS server, if any. This setting has no effect if the ‘Learn NetBIOS information from WAN’ is activated.
NetBIOS Scope
This is an advanced setting and is normally left blank. This allows the configuration of a NetBIOS ‘domain’ name under which network hosts operate. This setting has no effect if the ‘Learn NetBIOS information from WAN’ is activated.
NetBIOS Registration mode
Indicates how network hosts are to perform NetBIOS name registration and discovery.
H-Node, this indicates a Hybrid-State of operation. First WINS servers are tried, if any, followed by local network broadcast. This is generally the preferred mode if you have configured WINS servers.
M-Node (default), this indicates a Mixed-Mode of operation. First Broadcast operation is performed to register hosts and discover other hosts, if broadcast operation fails, WINS servers are tried, if any. This mode favours broadcast operation which may be preferred if WINS servers are reachable by a slow network link and the majority of network services such as servers and printers are local to the LAN.
P-Node, this indicates to use WINS servers ONLY. This setting is useful to force all NetBIOS operation to the configured WINS servers. You must have configured at least the primary WINS server IP to point to a working WINS server.
B-Node, this indicates to use local network broadcast ONLY. This setting is useful where there are no WINS servers available, however, it is preferred you try M-Node operation first.
This setting has no effect if the ‘Learn NetBIOS information from WAN’ is activated.

Add/Edit DHCP Reservation
This option lets you reserve IP addresses, and assign the same IP address to the network device with the specified MAC address any time it requests an IP address. This is almost the same as when a device has a static IP address except that the device must still request an IP address from the D-Link router. The D-Link router will provide the device the same IP address every time. DHCP Reservations are helpful for server computers on the local network that are hosting applications such as Web and FTP. Servers on your network should either use a static IP address or use this option.

Computer Name
You can assign a name for each computer that is given a reserved IP address. This may help you keep track of which computers are assigned this way. Example: Game Server.

IP Address:
The LAN address that you want to reserve.
MAC Address
To input the MAC address of your system, enter it in manually or connect to the D-Link router’s Web-Management interface from the system and click the Copy Your PC’s MAC Address button.

A MAC address is usually located on a sticker on the bottom of a network device. The MAC address is comprised of twelve digits. Each pair of hexadecimal digits are usually separated by dashes or colons such as 00-0D-88-11-22-33 or 00:0D:88:11:22:33. If your network device is a computer and the network card is already located inside the computer, you can connect to the D-Link router from the computer and click the Copy Your PC’s MAC Address button to enter the MAC address.

As an alternative, you can locate a MAC address in a specific operating system by following the steps below:

Windows 98
Windows Me Go to the Start menu, select Run, type in winipcfg, and hit Enter. A popup window will be displayed. Select the appropriate adapter from the pull-down menu and you will see the Adapter Address. This is the MAC address of the device.
Windows 2000
Windows XP Go to your Start menu, select Programs, select Accessories, and select Command Prompt. At the command prompt type ipconfig /all and hit Enter. The physical address displayed for the adapter connecting to the router is the MAC address.
Mac OS X Go to the Apple Menu, select System Preferences, select Network, and select the Ethernet Adapter connecting to the D-Link router. Select the Ethernet button and the Ethernet ID will be listed. This is the same as the MAC address.

DHCP Reservations List
This shows clients that you have specified to have reserved DHCP addresses. An entry can be changed by clicking the Edit icon, or deleted by clicking the Delete icon. When you click the Edit icon, the item is highlighted, and the “Edit DHCP Reservation” section is activated for editing.
Number of Dynamic DHCP Clients
In this section you can see what LAN devices are currently leasing IP addresses.

Revoke
The Revoke option is available for the situation in which the lease table becomes full or nearly full, you need to recover space in the table for new entries, and you know that some of the currently allocated leases are no longer needed. Clicking Revoke cancels the lease for a specific LAN device and frees an entry in the lease table. Do this only if the device no longer needs the leased IP address, because, for example, it has been removed from the network.
Reserve
The Reserve option converts this dynamic IP allocation into a DHCP Reservation and adds the corresponding entry to the DHCP Reservations List.

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