D-Link DWS-3024L, Руководство пользователя

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Network Planning to Support Layer 3 Roaming 37
2 Planning the D-Link Unified Access System Network
of the D-Link Access Point is about 100 meters, but the range is affected by various
environmental factors.
To maximize the range, use the following guidelines for the placement of the AP:
• Place the AP in an area where you expect wireless clients will operate.
• Elevated locations, such as on top of a shelf are preferred to increase line-of-sight access.
• Avoid placing the AP near sources of interference, such as PCs, microwaves, and 2.4 GHz
cordless phones.
• Keep the AP away from large metal surfaces.
• Position the antenna horizontally to increase the up-and-down range, or position it
vertically to increase side-to-side coverage.
• When APs are within broadcast range of each other, use non-interfering RF channels (five
channels apart for the 802.11b/g radio).
How close you place APs to each other depends on the RF transmission power level, the
number of wireless clients on your network, and the channels the APs use. The RF signal
transmission power level directly affects the broadcast range of the AP signal. If the power
level is too low, wireless clients will not detect the signal or experience poor WLAN
performance. If the power level is too high, the RF signal might interfere with other APs
within range. If the RF signal broadcasts beyond the physical confines of your building or
network, it increases the security threat to the network.
When the power level is high and RF broadcast area is larger, more wireless clients can detect
the signal and associate with the AP. An increase in the number of wireless clients that
associate with the AP generally means that the amount of traffic the AP receives and transmits
increases as well. You can limit the network utilization level allowed on an AP to prevent
wireless clients from experiencing slower network speeds. However, once the network
utilization is reached, new clients are unable to associate with the AP. If an AP frequently
reaches the network utilization limit, it might indicate that you should add another AP nearby.
You can configure the APs to automatically adjust the power and channel to the needs of the
network environment.
Network Planning to Support Layer 3 Roaming
With the D-Link Unified Access System, mobile stations can maintain their IP connections
while roaming from one access point to another even when these access points are attached to
different IP subnets. This feature enables Voice over IP (VoIP) deployments on 802.11
subnetted networks.
It is often necessary to subdivide the enterprise IPv4 network into several subnets. An access
point may be directly attached to the Unified Switch or it may be located several router hops
away from the Unified Switch.
To support layer 3 roaming, it is necessary to keep the wireless client's IP address unchanged
while it roams over different subnets. This guarantees seamless roaming as the IP changeover
process does not take place while wireless clients roam across subnet borders.