Specifications

Introduction
Altitude 4700 Series Access Point Product Reference Guide
20
Proxy ARP Support
With this most recent release of the Access Point firmware, the Access Point can respond to ARP
requests on behalf of an associated MU and protect the MU’s network credentials from being
broadcasted on a publicly accessible network.
When Proxy ARP is enabled on the Access Point (it’s enabled by default), the Access Point can make an
MU physically located on one network appear part of a different network connected to the same Access
Point. Proxy AP allows the Access Point to “hide” an MU’s IP address behind the Access Point’s
firewall, while still having the MU appear to be on the public network. Proxy ARP supports both strict
and dynamic modes on the Access Point.
For example, when Proxy ARP is enabled on the Access Point (it’s disabled by default) and the Access
Point receives an ARP request (either a wired or wireless request) for the IP address of an associated
MU, the Access Point responds directly to the request (on behalf of the MU) instead of broadcasting the
ARP request over the publicly accessible wireless network.
When enabled, any system on the wireless network that ARPs for the IP address of an associated MU
will receive an ARP reply from the Access Point stating the requesting system should be sending
packets destined for the MU to Access Point instead. In turn, the Access Point forwards the requesting
packets to the target MU. Through this process, the Access Point can pass ARP requests in both
directions, making an MU appear to be connected to a public network even though it’s on a private
network hidden behind the Access Point.
For detailed information on configuring Proxy AP support of the Access Point, see “Enabling Wireless
LANs (WLANs)” on page 146.
Multi Cipher Support
Beginning with this release, professional installers have the option of deploying both new and legacy
MUs within the same WLAN. Multi cipher support extends the Access Point’s existing WLAN security
options by allowing dynamic WEP and 802.11i configurations to co-exist, and allowing multiple security
policies to be associated with the same ESSID on different WLANs. Within such an environment, legacy
MUs are capable of WEP, while new MUs are capable of WPA/2-TKIP and WPA2-CCMP encryption.
This particular form of multi cipher (security) support helps maintain the co-existence of dynamic WEP
and 802.11i based environments.
For information on configuring Multi Cipher support, see “Configuring Multi Cipher Support” on
page 216.
Dynamic Chain Selection
When enabled, dynamic chain selection forces an Access Point radio to transmit packets using legacy
transmit rates (11b, 11g and/or 11a rates) using a single transmit chain. Transmissions utilizing 11n rates
(MCS0–MCS15) continue to use a normal number of transmit chains, which may be 1, 2, or 3 depending
on the configuration and power source. If dynamic chain selection is disabled, all transmissions utilize
the same number of transmit chains. This feature is disabled by default.