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Beginner

aironet 800 settings

I have a question about 802.11n settings. I have the default radio channel set to 11 and the channel width set to below 40 MHz.

Is this correct or should the channel width be set to above 40 MHz?

I'm finding a large number of receive CRC errors. Should I decrease the fragmentation threshold and the RTS threshold and to what should I reduce them to?

regards, Mark

25 REPLIES 25
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Hall of Fame Community Legend

I find that when all the devices are off and one desktop is on I can get 4 MBps file download from a NAS connected to a GB switch that is connected to the 887W.

Ok, things are getting clearer now.

Is the desktop connected by wired or wireless?

Have you tried directly connecting the desktop to the NAS via the GigabitEthernet switch and determine the speed?

Did you check for any line errors on the 880W's LAN port?

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If I connect the desktop to the GB switch I get 50 MBps file transfer.

The desktop is using wireless and I'm now getting 4 MBps that is about 35 Mbps - a long way from 300 Mbps

Apart from the person next door having an AP on channel 6 there are no sources of RF interference. When I did a test on the 887W I found that all channels were registering near to 0% utilisation.

I still get high receive CRC errors though and have figured through reading this could be the desktop PCIe card. I'm going to get 5dbi antennas for the desktop PCIe card that I can sit on top of the desktop to see if this boosts the connection.

Any other ideas for the setup would be welcome.

In the house we also have an iPad - but this is off most of the time.

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Hall of Fame Community Legend

The desktop is using wireless and I'm now getting 4 MBps that is about 35 Mbps - a long way from 300 Mbps

No, that is NOT possible.  You cannot connect 802.11 b/g/n and hope to achieve 300 Mbps.

I still get high receive CRC errors though and have figured through reading this could be the desktop PCIe card. I'm going to get 5dbi antennas for the desktop PCIe card that I can sit on top of the desktop to see if this boosts the connection.

How many antenna have you installed on the router?  If you remote into your AP, can you post the output to the command "sh dot11 as "?

If I connect the desktop to the GB switch I get 50 MBps file transfer.

Connect the NAS to the 10/100 LAN port of the router.

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I do realise that 300 Mbps is a theoretical max. What I was trying to say was that I would expect to get about 150 Mbps or more.

I have connected the NAS to the FE ports in the past - but of course being FE there is no jumbo packet  - another feature of this device. I get about the same speed as now when I do this connection.

AgamaAP#sh dot11 as 90F6.5247.16D5
Address           : 90f6.5247.16d5     Name             : NONE
IP Address        : 192.168.1.91       Interface        : Dot11Radio 0
Device            : unknown            Software Version : NONE
CCX Version       : NONE               Client MFP       : Off

State             : Assoc              Parent           : self
SSID              : AgamaAP
VLAN              : 1
Hops to Infra     : 1                  Association Id   : 3
Clients Associated: 0                  Repeaters associated: 0
Tunnel Address    : 0.0.0.0
Key Mgmt type     : WPAv2 PSK          Encryption       : AES-CCMP
Current Rate      : m5.-               Capability       : WMM ShortHdr ShortSlot
Supported Rates   : 1.0 2.0 5.5 11.0 6.0 9.0 12.0 18.0 24.0 36.0 48.0 54.0 m0. m1. m2. m3. m4. m5. m6. m7. m8. m9. m10. m11. m12. m13. m14. m15.
Voice Rates       : disabled           Bandwidth        : 40 MHz
Signal Strength   : -58  dBm           Connected for    : 9825 seconds
Signal to Noise   : 30  dB            Activity Timeout : 60 seconds
Power-save        : Off                Last Activity    : 0 seconds ago
Apsd DE AC(s)     : NONE

Packets Input     : 52910545           Packets Output   : 26597964
Bytes Input       : 1779354877         Bytes Output     : 1061094854
Duplicates Rcvd   : 8873828            Data Retries     : 7680778
Decrypt Failed    : 0                  RTS Retries      : 0
MIC Failed        : 0                  MIC Missing      : 0
Packets Redirected: 0                  Redirect Filtered: 0
Session timeout   : 0 seconds
Reauthenticate in : never

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Hall of Fame Community Legend

The output shows very, very good signal betweeen the AP and the desktop.

I do realise that 300 Mbps is a theoretical max.

No, that's not what I meant.  What I and Scott have been trying to tell you is this:  In order for anyone to reach 300 Mbps in 802.11n, you need to have 802.11a in a 40 Mhz channel-bond.  The "best" speed you can get is 802.11g.

I have connected the NAS to the FE ports in the past - but of course being FE there is no jumbo packet  - another feature of this device. I get about the same speed as now when I do this connection.

Sorry?  You did what???  You enabled Jumbo frames in your Gig switch????  Gee whiz, if this is what you've done, then no wonder you're getting slow responses.

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To be clear my network has jumbo frame turned off in all devices due to the 887W being incompatible.

I have friends who have the same desktop wireless cards and achieve 180 Mbps or higher. The difference is they have draytek, billion or other ADSL2+/router/wireless APs.

Do you have any suggestions on what I can achieve or do to improve the throughput - not what I cannot achieve.

Are you saying the 887W is only capable of 802.11g? Is this another Cisco feature?

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Are you saying the 887W is only capable of 802.11g? Is this another Cisco feature?

Yes.  The exact model of your in-built AP is AP801.  The "1" means you have 802.11 b/g radio.  If you disable data rates 11 Mbps and below, you'll get 802.11g speed (better than 802.11b).

I have friends who have the same desktop wireless cards and achieve 180 Mbps or higher

Ok, you have an 802.11 b/g AP.  Let's presume you're in a large open space.  No walls, nothing.  Just you and your router/AP.  You turn on the AP and, say go 5 feet away.  Yes, you WILL get 150 Mbps.  Put yourself back in your house, with walls, your neihbor's 802.11b wifi, turn on our bluetooth and your microwave oven (please don't forget your DECT cordless phone), and what do you get?  You get Jack.

Back to your issue.  I want to know what's causing the big discrepancies in speed.

Plug the NAS to the router's LAN port.  Plug your desktop to your LAN port.  Run the backup. 

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thank you for clarifying the matter. I will purchase another device and throw the cisco in the bin. I have slowly whittled away at reducing cisco devices (primarily because of the excessive cost and poor performance) and this is justification to get rid of this one too.

I did not see anywhere in the documentation that I read before I bought the unit that it was a pseudo 802.11n device. But given that I also missed the fact that the ports were fast ethernet and nothing better I need to pay more attention to the specs.

As a matter of interest what cisco device would do 802.11n / ADSL2+ and have a 4 port gig switch that you would identify as being worthwhile?

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Hey Mark,

What country are you in?

I will purchase another device and throw the cisco in the bin.

Chuck this in e-bay.  With an 8X7W, you'll get alot of gooooooooooooooooooooooooooood offers.

But given that I also missed the fact that the ports were fast ethernet and nothing better I need to pay more attention to the specs.

Yes it does.  In the Data Sheet it mentions "Four-port 10/100".

As a matter of interest what cisco device would do 802.11n / ADSL2+ and have a 4 port gig switch that you would identify as being worthwhile?

1941W is a router with an 802.11 a/b/g/n.

For DSL2+, you need an optional HWIC-1ADSL.

4-port Gig switch (non-PoE) is the EHWIC-4ESG.

In Australia.

I'm in Canberra.  Be careful what you are doing/going.  Where I live, I'll be getting NBN in May 2013.  Understand how fast this router will go and, when NBN is ready for you, what speed you want to get.

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In Australia. I will sell when I buy a new unit. There does not appear to be a cisco product that is reasonably priced and fits my needs. I will have a look at linksys but probably one of the other brands.

thank you for your help today. gotta go out now.

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Hall of Fame Community Legend

Email the support for your DSL provider and tell them that you have an 887W and whether or not they can provide you with the config.