Netopia 4000-Series manual Dhcp example

B-10 Firmware User Guide

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Block of IP host addresses

(derived from network IP address + mask issued by ISP)

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	Distributed to the Router
2	(Ethernet IP address)
		Manually distributed
3		(static)
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9		Pool of addresses distributed
10		by MacIP and DHCP
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The figure above shows an example of a block of IP addresses being distributed correctly.

The example follows these rules:

■An IP address must not be used as a static address if it is also in a range of addresses being distributed by DHCP or MacIP.

■A single IP address range is used by all the address-served clients. These include DHCP, BootP, MacIP, and WAN clients, even though BootP and static MacIP clients might not be considered served.

■The address range specified for address-served clients cannot wrap around from the end of the total available range back to the beginning. See below for a further explanation and an example.

■The network address issued by an ISP cannot be used as a host address.

A DHCP example

Suppose, for example, that your ISP gave your network the IP address 199.1.1.32 and a 4-bit subnet mask. Address 199.1.1.32 is reserved as the network address. Address 199.1.1.47 is reserved as the broadcast address. This leaves 14 addresses to allocate, from 199.1.1.33 through 199.1.1.46. If you want to allocate a sub-block of 10 addresses using DHCP, enter “10” in the DHCP Setup screen’s Number of Addresses to Allocate item. Then, in the same screen’s First Address item, enter the first address in the sub-block to allocate so that all 10 addresses are within your original block. You could enter 199.1.1.33, or 199.1.1.37, or any address between them. Note that if you entered 199.1.1.42 as the first address, network routing errors would probably result because you would be using a range with addresses that do not belong to your network (199.1.1.49, 199.1.1.50, and 199.1.1.51). The DHCP server would not initialize if set incorrectly.