Cisco Cisco Aironet 340 Ethernet Bridges Guia De Resolução De Problemas
Sub−optimal/Incorrect Data Rate Settings on the Wireless Bridges
2.
Fresnel Zone and Line of Sight Issues
3.
Problems with Antenna Alignment
4.
Clear Channel Assessment Parameter (CCA)
5.
Other Issues that Degrade the Performance of Wireless Bridges
6.
Radio Frequency Interference
Radio Frequency Interference (RFI) involves the presence of unwanted interfering RF signals that disrupt the
original data signals from wireless devices. RFI in a wireless network can lead to adverse effects, for example,
intermittent connectivity loss, poor throughput, and low data rates. There are different types of RFI that can
occur in a wireless network environment, and you must tale these RFI types into consideration before you
implement wireless networks. RFI types include narrowband RFI, all−band RFI, and RFI due to adverse
weather conditions.
original data signals from wireless devices. RFI in a wireless network can lead to adverse effects, for example,
intermittent connectivity loss, poor throughput, and low data rates. There are different types of RFI that can
occur in a wireless network environment, and you must tale these RFI types into consideration before you
implement wireless networks. RFI types include narrowband RFI, all−band RFI, and RFI due to adverse
weather conditions.
Narrowband RFINarrowband signals, depending on the frequency and signal strength, can
intermittently interrupt or even disrupt RF signals from a spreadspectrum device, such as a wireless
bridge. The best way to overcome narrowband RFI is to identify the source of the RF signal. You can
use Spectrum analyzers to identify the source of the RF signal.
intermittently interrupt or even disrupt RF signals from a spreadspectrum device, such as a wireless
bridge. The best way to overcome narrowband RFI is to identify the source of the RF signal. You can
use Spectrum analyzers to identify the source of the RF signal.
Spectrum analyzers are devices that you can use to identify and measure the strength of interfering RF
signals. When you identify the source, you can either remove the source to eliminate RFI, or shield
the source properly. Narrowband signals do not disrupt original data RF signals (from a wireless
bridge) across the entire RF band. Therefore, you can also choose an alternate channel for the bridge
where no narrowband RF interference occurs. For example, if unwanted RF signals disrupt one
channel, say channel 11, you can configure the wireless bridge to use another channel, say channel 3,
where there is no narrowband RFI.
signals. When you identify the source, you can either remove the source to eliminate RFI, or shield
the source properly. Narrowband signals do not disrupt original data RF signals (from a wireless
bridge) across the entire RF band. Therefore, you can also choose an alternate channel for the bridge
where no narrowband RF interference occurs. For example, if unwanted RF signals disrupt one
channel, say channel 11, you can configure the wireless bridge to use another channel, say channel 3,
where there is no narrowband RFI.
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All−band RFIAs the name suggests, all−band interference involves any unwanted RF signal that
interferes with the data RF signal across the entire RF band. All−band RFI can be defined as the
interference that covers the whole spectrum that the radio uses. The entire RF band does not point to
the ISM band alone. The RF band covers any band of frequencies that the wireless bridges use.
interferes with the data RF signal across the entire RF band. All−band RFI can be defined as the
interference that covers the whole spectrum that the radio uses. The entire RF band does not point to
the ISM band alone. The RF band covers any band of frequencies that the wireless bridges use.
A possible source of all−band interference that you can find commonly is a microwave oven. When
all−band interference is present, the best possible solution is to use a different technology, for
example, move from 802.11b to 802.11a (which uses the 5Ghz band). Also, the whole spectrum that
the radio uses is 83.5 MHz in FHSS (the whole ISM band), while for DSSS it is only 20 MHz (one of
the sub−bands). The chances of an interference that covers a range of 20 MHz are greater than the
chances of an interference that covers 83.5 MHz. If you cannot change technologies, try to find and
eliminate the source of the all−band interference. However, this solution can be difficult, because you
have to analyze the entire spectrum to track the source of the interference.
all−band interference is present, the best possible solution is to use a different technology, for
example, move from 802.11b to 802.11a (which uses the 5Ghz band). Also, the whole spectrum that
the radio uses is 83.5 MHz in FHSS (the whole ISM band), while for DSSS it is only 20 MHz (one of
the sub−bands). The chances of an interference that covers a range of 20 MHz are greater than the
chances of an interference that covers 83.5 MHz. If you cannot change technologies, try to find and
eliminate the source of the all−band interference. However, this solution can be difficult, because you
have to analyze the entire spectrum to track the source of the interference.
•
RFI Due to Adverse Weather ConditionsSeverely adverse weather conditions, for example,
extreme wind, fog, or smog can affect the performance of wireless bridges, and lead to intermittent
connectivity issues. In these situations, you can use a radome to protect an antenna from the
environmental effects. Antennas that do not have radome protection are vulnerable to environmental
effects, and can cause degradation to the performance of the bridges. A common problem that can
occur if you do not use the radome is the one due to rain. Raindrops can accumulate on the antenna
and affect performance. Radomes also protect an antenna from falling objects, such as ice that falls
from an overhead tree. With the Cisco Outdoor Bridge Range Calculation Utility, you can choose
your climate and terrain, and the program compensates for any degradation in weather.
extreme wind, fog, or smog can affect the performance of wireless bridges, and lead to intermittent
connectivity issues. In these situations, you can use a radome to protect an antenna from the
environmental effects. Antennas that do not have radome protection are vulnerable to environmental
effects, and can cause degradation to the performance of the bridges. A common problem that can
occur if you do not use the radome is the one due to rain. Raindrops can accumulate on the antenna
and affect performance. Radomes also protect an antenna from falling objects, such as ice that falls
from an overhead tree. With the Cisco Outdoor Bridge Range Calculation Utility, you can choose
your climate and terrain, and the program compensates for any degradation in weather.
•
CRC, PLCP errors
CRC errors and PLCP errors can occur due to Radio Frequency interference. The more radios a cell has (APs,
Bridges or Clients), the more are the chances of the occurrence of these errors. A cell means a single channel
Bridges or Clients), the more are the chances of the occurrence of these errors. A cell means a single channel