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manually defined hosts that are either turned off or temporarily off the network.
In that case, duplicate address problems might occur when a manually defined
host re-accesses the network and its IP address is not explicitly excluded.
What is a Reasonable Lease Time?
The default lease time is 24 hours. The lease time that you choose depends largely
on your needs, including the following:
v The number of hosts to support compared to the number of available addresses.
If you have more hosts than addresses, choose a short lease time of one to two
hours. This ensures that unused addresses are returned to the pool as soon as
possible. Keep in mind that the DHCP lease time affects your network operation
and performance.
– Shorter lease times increase the amount of network traffic due to DHCP lease
renewal requests. For example, if you set a lease time of 5 minutes, each
client sends a renewal request about every 2.5 minutes.
– Longer lease times limit your ability to reuse IP addresses. Extremely long
lease times also delay configuration changes that occur when a client restarts
or renews a lease.
v The time available to make network changes.
Hosts receive changes to configuration information when they are restarted or
when they renew their lease. Allow a timely and adequate window to make these
changes. For example, if you usually make changes overnight, you might assign
a lease time of 12 hours.
v The number of available DHCP servers.
If you have only a few DHCP servers for a large network, choose a longer lease
time to minimize the impact of server downtime.
Setting Up a DHCP Network
The IBM DHCP server provides configuration information to clients. This information
is based both on statements contained within the server’s configuration file and on
information provided by the client. The server’s configuration file defines the policy
for allocating IP addresses and other configuration parameters. The file is a
map
that the server uses to determine what information to provide to the requesting
client.
Before you start the DHCP server, use Operations Navigator to create or change
the DHCP server configuration file. Figure 241 on page 409 represents the DHCP
Server Configuration window.
408 OS/400 TCP/IP Configuration and Reference V4R4