Airespace AS-4012, Product Manual

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10/10/03 External DHCP Servers
90-100584-004 Airespace Product Guide 16
About External DHCP Servers
External DHCP Servers
The AireOS is designed to operate as a ‘DHCP Proxy’ with industry-standard external DHCP Servers that
support DHCP Relay. This means that each Airespace Wireless Switch or WLAN Appliance appears as a
DHCP Relay agent to the DHCP Server. This also means that the Airespace Switch or Appliance appears
as a DHCP Server to wireless clients at the virtual IP address.
Because the Airespace Switch or Appliance controls the client IP address obtained from a DHCP Server,
it maintains the same IP address for that client during same-Airespace Switch or Appliance,
inter-Airespace Switch and Appliance, and inter-subnet
Client Roaming .
Per-WLAN Assignment
Per-WLAN Assignment
All Airespace WLANs can be configured to use the same or different DHCP Servers, or no DHCP Server.
This allows operators considerable flexibility in configuring their Wireless LANs, as further described in
the
Airespace WLANs section.
Note that Airespace WLANs that support Management over Wireless must allow the management
clients to obtain an IP address from a DHCP Server.
Security Considerations
Security Considerations
For enhanced security, it is recommended that operators require all clients to obtain their IP addresses
from a DHCP server. To enforce this requirement, all
Airespace WLANs can be configured with a ‘DHCP
Required’ setting and a valid DHCP Server IP address, which disallows client static IP addresses. If a
client associating with a WLAN with ‘DHCP Required’ set does not obtain its IP address from the desig-
nated DHCP Server, it is not allowed access to any network services.
If slightly less security is tolerable, operators can create
Airespace WLANs with ‘DHCP Required’
disabled and a valid DHCP Server IP address. Clients then have the option of using a static IP address
or obtaining an IP address from the designated DHCP Server.
Operators are also allowed to create separate
Airespace WLANs with ‘DHCP Required’ disabled and a
DHCP Server IP address of 0.0.0.0. These WLANs drop all DHCP requests and force clients to use a
static IP address. Note that these WLANs do not support
Management over Wireless .