Amer Networks E5Web GUI - Manual (Page 372)

Advanced IP Pool Options
Advanced options available for IP Pool configuration are:
Routing Table The routing table to be used for lookups when resolving the
destination interfaces for the configured DHCP servers.
Receive Interface 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 cOS Core. 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.
MAC Range 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.
Prefetch leases 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).
Maximum free 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.
Maximum clients Optional setting used to specify the maximum number of clients (IPs)
allowed in the pool.
Sender IP This is the source IP to use when communicating with the DHCP
server.
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 cOS Core. 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:
Device:/> ippool -show
Chapter 5: DHCP Services
372