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Question : Wireless PtP Bridge Configuration
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I'm using the following equipment to bridge two buildings approx. 750m apart:
D-Link DWL-2700AP outdoor AP with ANT24-1800 directional panel antenna
-in PtP Bridge mode and I have supplied the remote AP MAC address
D-Link DWL-3200AP indoor AP with ANT24-1400 directional panel antenna
-in WDS mode with remote AP MAC address supplied
Questions:
1. The antennas have clear line of sight. RSSI is approx. 35%. Isn't that low for the range in this application?
2. I thought the above configuration would mean that only the two APs would be able to communicate, but there are other clients listed in both APs. Do I need to add the MAC of the remote AP to the filter/accept list? Why doesn't the remote AP appear in the client table?
3. The APs in the bridge configuration are on channel 7. I have another AP in AP mode that is on a different channel. Is this appropriate or should they all be on the same channel?
4. Here are some stats from both APs, do the RTS failure count and Received Frame FCS Error Counts indicate a problem?
---[ DWL-2700AP ]-------------------------
WLAN 802.11G Traffic Statistics
ThroughPut
Transmit Success Rate 100 %
Transmit Retry Rate: 0 %
Receive Success Rate: 96 %
Receive Duplicate Rate: 0 %
RTS Success Count: 2
RTS Failure Count: 17539
Transmitted Frame Count
Transmitted Frame Count 163711
Multicast Transmitted Frame Count 14252
Transmitted Error Count: 0
Transmitted Total Retry Count: 207
Transmitted Multiple Retry Count: 207
Received Frame Count
Received Frame Count 378714
Multicast Received Frame Count 27165
Received Frame FCS Error Count: 17539
Received Frame Duplicate Count: 0
Ack Rcv failure Count: 0
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---[ DWL-3200AP ]-------------------------
WLAN 802.11G Traffic Statistics
Throughput
Transmit Success Rate 99 %
Transmit Retry Rate 0 %
Receive Success Rate 54 %
Receive Duplicate Rate 1 %
RTS Success Count 57
RTS Failure Count 389031
Transmitted Frame Count
Transmitted Frame Count 406152
Multicast Transmitted Frame Count 5
Transmitted Error Count 6143
Transmitted Total Retry Count 0
Transmitted Multiple Retry Count 0
Received Frame Count
Received Frame Count 453908
Multicast Received Frame Count 0
Received Frame FCS Error Count 389031
Received Frame Duplicate Count 8780
Ack Rcv failure Count 114046
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Answer : Wireless PtP Bridge Configuration
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1) It sounds reasonable. The max range for normal access points is about 300m so with good directional antennas I would expect about a 1KM max range. You are therefore operating neer the max range (depending on how good the antennas are).
2) Many access points can work as access points and in bridge mode simultaneously. I would make sure WEP is configured and also have the filter defined so that only the MAC address of the access pojnts can connect to each other.
3) If the 3rd AP is bridged to either of the first two then it must be on the same channel. Otherwise it much be on a different channel. Also all channels you use should be at least 2 apart. This is because channel 2 shares half of the frequencies used by channels 1 and 3 etc...
Many D-Link products can work in a mode where they bond two channels together to double the bandwidth.
4) Receive Success Rate 54 %
This does not look too good. I would try other channels incase someone else in your area is using the same channel and causing interferance. You can also switch the two access points over to see if the error count moves with it. Maybe one of the APs or the antennas is not as good as the other.
When the received signal level drops the speed of the link is automatically reduced. If you are finding that there is a lot of errors you could try manually reducing the max bandwidth so that the speed of the link is reduced. This may reduce the errors and could increase the overall speed.
Basically you need to experiment and see how it affects the real speed of the link by timing the copying of a large file across it.
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