WESM zl Management and Configuration Guide WT.01.28 and greater

6-23
IP Services—IP Settings, DHCP, and DNS
DHCP Server
As a DHCP server, the Wireless Edge Services zl Module can also implement
dynamic DNS (DDNS), which updates a DNS server whenever a host’s IP address
changes.
Finally, the Wireless Edge Services zl Module supports DHCP relay.
Configuring the DHCP Server
If you want the Wireless Edge Services zl Module to assign IP addresses to devices
on your network, you must configure it as a DHCP server by following the steps
outlined in the following sections. You can access all of the options necessary to
configure the DHCP server from the Network Setup > DHCP Server screen in the
Web browser interface.
To run the DHCP server on a VLAN, the VLAN must meet these requirements:
■ It must have a static IP address. (See “Assigning an IP Address to a VLAN” on
page 6-5.)
■ It must not implement DHCP relay.
DHCP relay configurations take precedence over the DHCP server. In other
words, if you associate a VLAN interface with a network pool and you also
implement DHCP relay on that interface, the module does not respond to DHCP
requests on that VLAN. Instead it relays requests to an external server.
After configuring the DHCP server, you must enable it. If the server is already
enabled, any configurations you make to it take effect only after the server restarts.
The DHCP server automatically restarts 30 seconds after you apply a change. You
can also manually restart the server.
Creating DHCP Pools
As a DHCP server, the Wireless Edge Services zl Module requires one or more pools
from which to issue configurations to devices. You can configure either a network
pool or a host pool.
A network pool includes a range of IP addresses from which the DHCP server can
choose as it responds to DHCP requests. The Wireless Edge Services zl Module
associates each network pool with a particular VLAN. When a station in that VLAN
sends a DHCP request, the module responds with one of the addresses from the
associated pool.
When you use network pools, you can also specify a range of excluded addresses,
which are addresses in a pool that the Wireless Edge Services zl Module is not allowed
to assign. Use the excluded addresses to protect IP addresses on your network that
you want to remain fixed, such as the IP addresses of routers and DNS servers.