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DaveO

join:2001-09-05
Easley, SC

Slow 802.11n Wireless

I added two Trendnet 802.11n access points to an Active Directory domain, but the wireless clients are getting networking performance that's much slower than they get from 100Mbit ethernet. The wireless clients all have 802.11n PCI cards.

Here are the signal levels from a machine near an APs:
Link Quality 100%
Signal Strength 1 -51 dBm
Signal Strength 2 -49 dBm
Signal Strength 3 -47 dBm
Noise Strength 26% -92 dBm

Do those look OK?

I seem to be getting many CRC errors on sending and receiving:
Frames Transmitted Successfully 9671
Frames Retransmitted Successfully 2880

Frames Received 15103
Frames Received with CRC Error 1575

Is that normal for 802.11n wireless? Thanks.



prestonlewis
Premium,MVM
join:2003-04-13
Sacramento, CA

You don't mention whether the wireless client pre-n cards are also Trendnet. In the pre-n world, all devices in the N network must be by the same manufacturer, at least for now. Trendnet N products tend to get a really good review from sites like CNET, above other big name manufacturers like Netgear. If your client devices aren't Trendnet clients, that's likely your problem. What model of Trendnet pre-n access point are you using? What model of client pre-n devices are you using? If you'll post the models for these, a better answer can be given.


DaveO

join:2001-09-05
Easley, SC

prestonlewis, thanks for the reply. The APs and the wireless network cards are actually all Draft 2.0, not pre-n. The APs are Trendnet TEW-637AP, and the wireless cards are Encore ENLWI-N.


stevech0

join:2006-09-17
San Diego, CA
reply to DaveO

said by DaveO:

I added two Trendnet 802.11n access points to an Active Directory domain, but the wireless clients are getting networking performance that's much slower than they get from 100Mbit ethernet. The wireless clients all have 802.11n PCI cards.

Here are the signal levels from a machine near an APs:
Link Quality 100%
Signal Strength 1 -51 dBm
Signal Strength 2 -49 dBm
Signal Strength 3 -47 dBm
Noise Strength 26% -92 dBm

Do those look OK?

I seem to be getting many CRC errors on sending and receiving:
Frames Transmitted Successfully 9671
Frames Retransmitted Successfully 2880

Frames Received 15103
Frames Received with CRC Error 1575

Is that normal for 802.11n wireless? Thanks.
Very strong signal strengths. Typical of path lengths of just a few feet.

CRC error rate is high. Should be 10% or lower.
Could be:
1) incompatible client devices (draft-N issues)
2) Frame bursting or Turbo or SuperG or whatever marketing term, and both client and w-router/Access point don't have the same concept of what those terms mean (these are not defined by IEEE 802.11)
3) Channel bonding is turned on in the 11n devices. Problematic
4) Heavy interference from 2.4GHz devices such as cordless phone, analog wireless video camera. Or broadband noise from a microwave or nearby airport radar.

DaveO

join:2001-09-05
Easley, SC
reply to DaveO

stevech0, I'm thinking the Channel Bonding might be the problem. It's turned on in both access points, and they overlap in coverage. How do two APs both use 2 channels given that there are only 3 non-overlapping channels(1, 6, 11)? The APs are using channels 6 and 11. What should the Extension Channel be for them?



JohnInSJ
Premium
join:2003-09-22
Aptos, CA
reply to DaveO

said by DaveO:

the wireless clients are getting networking performance that's much slower than they get from 100Mbit ethernet.
What are they getting?
20-30mbit... problem
40-60mbit... typical real world speeds for N (not 5ghz)
60-80mbit... you have a very clean spectrum, congrats

The error rate does seem high... my draft 2.0 dlink gear (uptime several months...) shows
Sent :22591697
TX Packets Dropped :0
Received :14587502
RX Packets Dropped :0
Errors :31698

So my error rate is 0.000852574 - and I've got plenty of overlap with other people's and my own g networks...

You check for current drivers and all that jazz?

DaveO

join:2001-09-05
Easley, SC

JohnInSJ, I've done some rough speed tests transferring 51.3MB of files from the server. When plugged into the 100Mbit wired ethernet connection, clients can transfer 51.3MB in about 5.6 seconds, for a rate of about 73Mbit. Using the 802.11n access point it takes them over 20 seconds to transfer the same files. That's about 20Mbit on wireless.

Yes I'm using the most current drivers from the Encore web site. I'm going to take out one of the wireless NICs and take the NIC & access points with me to try them in another location to see if there is some kind of RF noise causing the problems.