D-Link DFL-260E User Manual page 239

5.4. IP Pools
Receive Interface
MAC Range
Prefetch leases
Maximum free
Maximum clients
Sender IP
Memory Allocation for Prefetched Leases
As mentioned in the previous section, the Prefetched Leases option specifies the size of the cache of
leases which is maintained by NetDefendOS. This cache provides fast lease allocation and can
improve overall system performance. It should be noted however that the entire prefetched number
of leases is requested at system startup and if this number is too large then this can degrade initial
performance.
As leases in the prefetch cache are allocated, requests are made to DHCP servers so that the cache is
always full. The administrator therefore has to make a judgement as to the optimal initial size of the
prefetch cache.
Listing IP Pool Status
The CLI command ippools can be used to look at the current status of an IP pool. The simplest form
of the command is:
gw-world:/> ippool -show
This displays all the configured IP pools along with their status. The status information is divided
into four parts:
• Zombies - The number of allocated but inactive addresses.
• In progress - The number of addresses that in the process of being allocated.
• Free maintained in pool - The number of addresses that are available for allocation.
• Used by subsystems - The number of addresses that are allocated and active.
A "simulated" virtual DHCP server receiving interface. This setting is
used to simulate a receiving interface when an IP pool is obtaining IP
addresses from internal DHCP servers. This is needed since the filtering
criteria of a DHCP server includes a Receive Interface.
An internal DHCP server cannot receive requests from the IP pool
subsystem on an interface since both the server and the pool are internal
to NetDefendOS. This setting allows such requests from a pool to
appear as though they come from a particular interface so that the
relevant DHCP server will respond.
A range of MAC addresses that will be use to create "fake" DHCP
clients. Used when the DHCP server(s) map clients by the MAC
address. An indication of the need for MAC ranges is when the DHCP
server keeps giving out the same IP for each client.
Specifies the number of leases to keep prefetched. Prefetching will
improve performance since there will not be any wait time when a
system requests an IP (while there exists prefetched IPs).
The maximum number of "free" IPs to be kept. Must be equal to or
greater than the prefetch parameter. The pool will start releasing (giving
back IPs to the DHCP server) when the number of free clients exceeds
this value.
Optional setting used to specify the maximum number of clients (IPs)
allowed in the pool.
This is the source IP to use when communicating with the DHCP server.
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Chapter 5. DHCP Services