Allied Telesis AT-WR4500 manual Store Leases on Disk, Submenu level /ip dhcp-server config

120	AT-WR4500 Series - IEEE 802.11abgh Outdoor Wireless Routers
	RouterOS v3 Configuration and User Guide

the source-address is left as 0.0.0.0, then the static address will be used. If there are multiple addresses on the interface, an address in the same subnet as the range of given addresses should be used use-radius(yes no; default: no) - whether to use RADIUS server for dynamic leases

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Client will only receive a DHCP lease in case it is directly reachable by its MAC address through that interface (some wireless bridges may change client's MAC address).If authoritative property is set to yes, the DHCP server is sending rejects for the leases it cannot bind or renew. It also may (although not always) help to prevent the network users to run their own DHCP servers illicitly, disturbing the proper way the network should be functioning.If relay property of a DHCP server is not set to 0.0.0.0 the DHCP server will not respond to the direct requests from clients.

Example

To add a DHCP client on ether1 interface:

/ip dhcp-server add name=dhcp-office disabled=no [admin@AT-WR4562] ip dhcp-server> print detail Flags: X - disabled, I – invalid

0interface=ether1 add-default-route=yes use-peer-dns=yes use-peer-ntp=yes status=bound address=192.168.0.65/24 gateway=192.168.0.1

dhcp-server=192.168.0.1 primary-dns=192.168.0.1 primary-ntp=192.168.0.1 expires-after=9m44s

dhcp-clients 02:00:00 [admin@AT-WR4562] ip dhcp-server>

￿

Client will only receive a DHCP lease in case it is directly reachable by its MAC address through that interface (some wireless bridges may change client's MAC address).If authoritative property is set to yes, the DHCP server is sending rejects for the leases it cannot bind or renew. It also may (although not always) help to prevent the network users to run their own DHCP servers illicitly, disturbing the proper way the network should be functioning.If relay property of a DHCP server is not set to 0.0.0.0 the DHCP server will not respond to the direct requests from clients.

Example

To add a DHCP server to interface ether1, lending IP addresses from dhcp-clientsIP pool for 2 hours:

/ip dhcp-server add name=dhcp-office disabled=no address-pool=dhcp-clients \

interface=ether1 lease-time=2h
[admin@AT-WR4562] ip dhcp-server> print
Flags: X - disabled, I – invalid
#	NAME	INTERFACE RELAY	ADDRESS-POOL LEASE-TIME ADD-ARP
0	dhcp-office	ether1	dhcp-clients 02:00:00

[admin@AT-WR4562] ip dhcp-server>

6.1.4 Store Leases on Disk

Submenu level: /ip dhcp-server config

Description

Leases are always stored on disk on graceful shutdown and reboot. If on every lease change it is stored on disk, a lot of disk writes happen. There are no problems if it happens on a hard drive, but is very bad on Compact Flash (especially, if lease times are very short). To minimize writes on disk, all changes are flushed together every store-leases-diskseconds. If this time will be very short (immediately), then no changes will be lost even in case of hard reboots and power losts. But, on CF there may be too many writes in case of short lease times (as in case of hotspot). If this time will be very long (never), then there will be no writes on disk, but information about active leases may be lost in case of power loss. In these cases dhcp server may give out the same ip address to another client, if first one will not respond to ping requests.