Motorola WS5100 Series Reference Manual page 19

• Detect interference from other systems and avoid co-channeling with those systems (most notably
radar systems).
• Provide uniform spectrum loading across all devices.
This feature is enabled automatically when the country code indicates that DFS is required for at
least one of the frequency bands that are allowed in the country.
• TPC – Transmit Power Control (TPC) meets the regulatory requirement for maximum power and mitigation
for each channel. TPC functionality is enabled automatically for every AP that operates on the channel.
802.11bg
• Dual mode b/g protection – ERP builds on the payload data rates of 1 and 2 Mbit/s that use DSSS
modulation and builds on the payload data rates of 1, 2, 5.5, and 11 Mbit/s, that use DSSS, CCK, and
optional PBCC modulations. ERP provides additional payload data rates of 6, 9, 12, 18, 24, 36, 48, and 54
Mbit/s. The transmission and reception capability for 1, 2, 5.5, 11, 6, 12, and 24 Mbit/s data rates is
mandatory.
Two additional optional ERP-PBCC modulation modes with payload data rates of 22 and 33 Mbit/s are
defined. An ERP-PBCC station may implement 22 Mbit/s alone or 22 and 33 Mbit/s. An optional
modulation mode (known as DSSS-OFDM) is also incorporated with payload data rates of 6, 9, 12, 18,
24, 36, 48, and 54 Mbit/s.
• Short slot protection – The slot time is 20 µs, except an optional 9 µs slot time may be used when the
BSS consists of only ERP STAs capable of supporting this option. The optional 9 µs slot time should not
be used if the network has one or more non-ERP STAs associated. For IBSS, the Short Slot Time field is
set to 0, corresponding to a 20 µs slot time.
1.2.2.3 Rate Limiting
Rate limiting controls the maximum rate sent or received on a network. Rate limiting enables the proper
allocation of bandwidth, based on the source MAC address, destination MAC address, source IP address,
destination IP address and/or TCP/UDP port number. Rate limiting allows the definition of two rates: a
guaranteed minimum bandwidth and a second burst size. Rate limiting is performed as part of the flow
control process between access ports and the switch.
1.2.2.4 Proxy-ARP
Proxy ARP is provided for MU's in PSP mode whose IP address is known. The WLAN generates an ARP reply
on behalf of a MU (if the MU's IP address is known). The ARP reply contains the MAC address of the MU (not
the MAC address of switch). Thus, the MU does not awaken to send ARP replies (increasing MU battery life
and conserving wireless bandwidth).
If an MU goes into PSP without transmitting at least one packet, its Proxy ARP will not work.
1.2.2.5 HotSpot / IP Redirect
A hotspot is a Web page users are forced to visit before they are granted access to the Internet. With the
advent of Wi-Fi enabled client devices (such as laptops and PDAs) commercial hotspots are common and can
be found at many airports, hotels and coffee shops.The Hotspot / IP Redirect feature allows the switch to
function as a single on-site switch supporting WLAN hotspots. The Hotspot re-directs user traffic (for a
hotspot enabled WLAN) to a Web page that requires them to authenticate before granting access to the
WLAN. The IP-Redirection requires no special software on the client but its does require the client be set to
receive its IP configuration through DHCP. The following is a typical sequence for hotspot access:
1. A visitor with a laptop requires hotspot access at a site.
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Overview