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New Member

Realworld Wireless speed and errors

I've got 4 1130ag's, three at one site and one at another.

I get just about 2Mbps over them. I've limited the AP's to only use G speeds per Cisco's docs, I've verified the ethernet port on the 3560's they plug into, they transfer at real 100Mbps Lan speeds, easily over 2Mbps :) Speakeasy test on my laptops over the wire is 8Mbps, over the AP's it's usually only 1.5Mbps.

I should get more than this with B! I'm using linksys wpc54gs ver 2 and Belking F5D7011 cards on around 20 laptops. Speed tests were taken on each individual AP with others powered off and no traffic to the two test machines (1 server and 1 laptop). The linksys card is slightly slower so I think it may be a driver/XP issue. I've downloaded all the latest drivers to no avail.

I get a LOT of errors in the ap stats screens:

Retries: 10408

Packets With One Retry: 6728

Packets With More Than One Retry: 1734

Duplicate Frames: 564

CRC Errors: 122

This is over 3 speakeasy tests and one 33MB file transfer test with the Belkin. There are no other wireless devices, phones, etc in the same band. Open air from about 10-15 feet from the AP's

Any ideas would be greatly appreciated.

26 REPLIES
Green

Re: Realworld Wireless speed and errors

Load Netstumbler (www.netstumbler.com) on the laptop nad take a look at the RF environment you're woring in.

NS will give you an indication of the best channel (1, 6, or 11) is the cleanest ... environmental interference as well as other wireless systems.

What kind of signal strength, *AND* what kind of signal quality are you seeing? Of the two, signal quality is much more important.

The indications from the stats you posted suggest interference and / or poor signal quality.

Good Luck

Scott

New Member

Re: Realworld Wireless speed and errors

That was my very first thought so I did use NS to take a look. I'm on channel 1, nothing else at all shows up. I also tried 11 and it was about 3-6 dB lower, no performance difference. Signals are:

Belkin:

SNR 68 (54 at chnl 11)

Noise -100

Signal -32 dBm (-46 at chnl 11)

Linksys:

SNR 47 (49-51 at chnl 11)

Noise -100

Signal -53 dBm (-47 at chnl 11)

Re: Realworld Wireless speed and errors

a drop of 3db = half the strength

a drop of 6db = quarter the strength.

Do the following, login to the AP's CLI and issue the following command. (change to appropriate radio)

show int dot11radio 0 statistics

Copy the results to your fav text editor.

Then issue:

clear dot11 statistics dot11Radio 0

Now wait 10 minutes or so and issue the first command again... Post the results.

show int dot11radio 0 statistics

New Member

Re: Realworld Wireless speed and errors

After:

DOT11 Statistics (Cumulative Total/Last 5 Seconds):

RECEIVER TRANSMITTER

Host Rx Bytes: 2097968 / 704 Host Tx Bytes: 2351077 /1079

Unicasts Rx: 7590 / 10 Unicasts Tx: 7006 / 10

Unicasts to host: 7590 / 10 Unicasts by host: 6905 / 10

Broadcasts Rx: 101 / 0 Broadcasts Tx: 13269 / 48

Beacons Rx: 0 / 0 Beacons Tx: 13033 / 48

Broadcasts to host: 101 / 0 Broadcasts by host: 235 / 0

Multicasts Rx: 0 / 0 Multicasts Tx: 1482 / 6

Multicasts to host: 0 / 0 Multicasts by host: 1478 / 6

Mgmt Packets Rx: 0 / 0 Mgmt Packets Tx: 101 / 0

RTS received: 0 / 0 RTS transmitted: 4 / 0

Duplicate frames: 7 / 0 CTS not received: 1 / 0

CRC errors: 701 / 0 Unicast Fragments Tx: 7003 / 10

WEP errors: 0 / 0 Retries: 1790 / 1

Buffer full: 0 / 0 Packets one retry: 770 / 1

Host buffer full: 0 / 0 Packets > 1 retry: 464 / 0

Header CRC errors: 0 / 0 Protocol defers: 178 / 0

Invalid header: 1 / 0 Energy detect defers: 454 / 0

Length invalid: 0 / 0 Jammer detected: 0 / 0

Incomplete fragments: 0 / 0 Packets aged: 0 / 0

Rx Concats: 0 / 0 Tx Concats: 0 / 0

Before:

DOT11 Statistics (Cumulative Total/Last 5 Seconds):

RECEIVER TRANSMITTER

Host Rx Bytes: 45681718 / 0 Host Tx Bytes: 590600614 / 315

Unicasts Rx: 295262 / 0 Unicasts Tx: 434310 / 0

Unicasts to host: 295262 / 0 Unicasts by host: 426141 / 0

Broadcasts Rx: 27845 / 0 Broadcasts Tx: 882486 / 49

Beacons Rx: 0 / 0 Beacons Tx: 875149 / 49

Broadcasts to host: 27845 / 0 Broadcasts by host: 7337 / 0

Multicasts Rx: 0 / 0 Multicasts Tx: 87408 / 6

Multicasts to host: 0 / 0 Multicasts by host: 87406 / 6

Mgmt Packets Rx: 0 / 0 Mgmt Packets Tx: 8169 / 0

RTS received: 0 / 0 RTS transmitted: 324 / 0

Duplicate frames: 2066 / 0 CTS not received: 292 / 0

CRC errors: 12252 / 0 Unicast Fragments Tx: 434262 / 0

WEP errors: 0 / 0 Retries: 64411 / 0

Buffer full: 0 / 0 Packets one retry: 26613 / 0

Host buffer full: 0 / 0 Packets > 1 retry: 18184 / 0

Header CRC errors: 0 / 0 Protocol defers: 21 / 0

Invalid header: 86 / 0 Energy detect defers: 6320 / 17

Length invalid: 0 / 0 Jammer detected: 0 / 0

Incomplete fragments: 0 / 0 Packets aged: 0 / 0

Rx Concats: 0 / 0 Tx Concats: 0 / 0

Re: Realworld Wireless speed and errors

The only thing i really see out of the ordinary is your Energy detect defers. This is the number of times your AP detected radio transmissions and waited befoer sending data.

However this could have just been during higher activity on your wirelses network.

Bronze

Re: Realworld Wireless speed and errors

Wow!

What kind of environment are you in? I'm guessing an airplane hanger with trees in it wrapped in chain link fence!

Seriously, the signals you have assuming a -100 dBm noise floor should be fine for voice and data in a clean environment.

I am assuming mulipath and that is what Scott was alluding to when he spoke of signal quality.

It is supposed to be a diversity antenna so that should be taken care of, but what is the power set to?

Please describe the environment. The walls floors, ceilings...office space, bank vault, Kryptonite factory, etc.

I would like to see the sh run and any results you got from a site survey.

Did it ever work or has it always been like this?

New Member

Re: Realworld Wireless speed and errors

One location is a single story office building, not much around it except a lot of parking lots. On the outer edges of the building (outside) I pick up 3 other wireless networks with NS, but the signal is so low I can't even associate to them. The building is brick with typical wood studs in the inner walls. Nothing too weird. The other site (where the readings are from but almost the same as the other location) is a house in a residential district, no other ap's even when walking around the yard perimeter. House was built in the 1960's, again nothing strange about it.

The speeds were better when I first installed everything, they just suddenly dropped in December. Nothing has changed.

I have power output set all the way up. What do you mean "the sh run"?

Bronze

Re: Realworld Wireless speed and errors

I'm sorry "sh run" is geek for 'show run' which is a command that you type in to the AP to show the configuration.

I would suggest turning the power down as much as possible, at least to test the throughput in a less "hot" environment.

However, if this doesn't show any marked improvement, you will have to test a new Known Good AP in this environment and test a Possibly Bad AP in a Known Clean Environment.

Something should reveal itself at that point; either the good one will work and you have crappy radios that need to be replaced or, the good one won't work in your current environment but the bad works fine outside of it.

Then you need to either get some serious spectrum analysis or move and call a priest.

Hall of Fame Super Red

Re: Realworld Wireless speed and errors

Hi John,

It's always nice to see some humor along with your good ideas :) I was laughing pretty good on these last two posts. 5 points from this end! I think your troubleshooting ideas were also very good.

Take care,

Rob

New Member

Re: Realworld Wireless speed and errors

Current configuration : 4552 bytes

version 12.3

no service pad

service timestamps debug datetime msec

service timestamps log datetime msec

service password-encryption

hostname -------

clock timezone UTC -7

clock summer-time UTC recurring

led display alternate

ip subnet-zero

ip name-server ---------

aaa new-model

aaa group server radius rad_eap

server --------- auth-port 1812 acct-port 1814

aaa group server radius rad_mac

aaa group server radius rad_acct

server --------- auth-port 1812 acct-port 1814

aaa group server radius rad_admin

server --------- auth-port 1812 acct-port 1814

cache expiry 1

cache authorization profile admin_cache

cache authentication profile admin_cache

aaa group server tacacs+ tac_admin

cache expiry 1

cache authorization profile admin_cache

cache authentication profile admin_cache

aaa group server radius rad_pmip

aaa group server radius dummy

aaa authentication login default local cache rad_admin group rad_admin

aaa authentication login eap_methods group rad_eap

aaa authentication login mac_methods local

aaa authorization exec default local cache rad_admin group rad_admin

aaa accounting network acct_methods start-stop group rad_acct

aaa cache profile admin_cache

all

aaa session-id common

dot11 ssid --------

authentication open

authentication key-management wpa

guest-mode

wpa-psk ascii 7 -----------------

dot11 aaa csid unformatted

dot11 network-map

bridge irb

interface Dot11Radio0

description 802.11G Radio

no ip address

no ip route-cache

encryption mode ciphers tkip

ssid ---------

speed basic-1.0 2.0 5.5 6.0 9.0 11.0 12.0 18.0 24.0 36.0 48.0 54.0

channel 2462

station-role root

no dot11 extension aironet

bridge-group 1

bridge-group 1 subscriber-loop-control

bridge-group 1 block-unknown-source

no bridge-group 1 source-learning

no bridge-group 1 unicast-flooding

bridge-group 1 spanning-disabled

interface Dot11Radio1

description 802.11A Radio

no ip address

no ip route-cache

encryption mode ciphers tkip

ssid ------------

speed basic-6.0 basic-9.0 basic-12.0 basic-18.0 basic-24.0 basic-36.0 basic-48.0 basic-54.0

station-role root

bridge-group 1

bridge-group 1 subscriber-loop-control

bridge-group 1 block-unknown-source

no bridge-group 1 source-learning

no bridge-group 1 unicast-flooding

bridge-group 1 spanning-disabled

interface FastEthernet0

description Ethernet Link

no ip address

no ip route-cache

duplex auto

speed auto

bridge-group 1

no bridge-group 1 source-learning

bridge-group 1 spanning-disabled

hold-queue 160 in

interface BVI1

ip address dhcp client-id FastEthernet0

no ip route-cache

ip http server

ip http authentication aaa

no ip http secure-server

ip http help-path http://www.cisco.com/warp/public/779/smbiz/prodconfig/help/eag

ip radius source-interface BVI1

snmp-server view dot11view ieee802dot11 included

snmp-server community public RO

snmp-server location --------------------

snmp-server contact Michael Hess

snmp-server chassis-id -----------

snmp-server enable traps snmp authentication linkdown linkup coldstart warmstart

snmp-server enable traps tty

snmp-server enable traps entity

snmp-server enable traps disassociate

snmp-server enable traps deauthenticate

snmp-server enable traps authenticate-fail

snmp-server enable traps dot11-qos

snmp-server enable traps switch-over

snmp-server enable traps rogue-ap

snmp-server enable traps wlan-wep

snmp-server enable traps config

snmp-server enable traps syslog

snmp-server enable traps cpu threshold

snmp-server enable traps aaa_server

snmp-server host ----------- public

radius-server attribute 32 include-in-access-req format %h

radius-server host ------------ auth-port 1812 acct-port 1814 key xxx

radius-server vsa send accounting

control-plane

bridge 1 route ip

wlccp wds aaa csid unformatted

line con 0

line vty 0 4

sntp broadcast client

end

New Member

Re: Realworld Wireless speed and errors

I replaced my wpa-ent with wpa-personal to rule out radius issues. I also tried as completley open, no diff. I tried with various data rate settings as well, all on, all off, g only, etc. I removed the user/password section as I assume that won't matter. Thanks for all the great suggestions guys! I do have a couple bluetooth devices in the general area that wouldn't show on NS, no cordless phones in that band though. I've tried with all the bluetooth devices off and it didn't have any affect.

Bronze

Re: Realworld Wireless speed and errors

just a couple of points...the G radio is set to 1.0 and up.

That should read speed basic-11.0 12.0 etc....

The channel for this AP is 11. If there are any microwave ovens around close to this AP, you will take a good hit when they turn it on.

Channel 11 is the closest one of the three to Channel 9 which is pretty close to the cenetr frequency of a standard microwave. It takes the worst hit.

I don't see any reason for guest mode to be in there, maybe I missed something.

There is no channel set for A.

I would at this point lower all my AP's down to like 10mW just to see what happens. I would do the same with all the client cards as well. If everything is at full power you are most likely causing your own multipath.

Ensure you are using three separate channels for G, (1,6,11)

I would then take a Card you know that Works Elsewhere and run some ping tests from the client to the AP and then to the Gateway and then to something on the network on the other side.

I would also get some Wireshark and sniff the air and see if anything catches your eye. Maybe one bad card is killing you..who knows.

If you have any (as in even one) B client the whole thing takes a dive. Since G wasn't around when they made B, the B clients cannot detect G traffic and the G traffic has to stop and make sure no B cards want to send traffic. You take a huge hit for that!

Not much else I can guess at. But at the very least rule out same channel interference by checking all your AP's, check your ping times with a continuous ping, make sure you are roaming properly and not sticking to one AP too long, No B clients - microwave locations,

wireshark the air and get a sniff and see what is dropping retransmitting etc...

Take the aluminum foil wall paper of the walls (haha) and remove the tinsel somebody draped on the AP for Christmas (Go ahead and giggle I have seen this in reality!)

And just for grins make sure there are no Draft -N products being used anywhere.

If you get past all that It would be Time To Spend Some Money and buy Cognio and perform a spectrum analysis and let it find any phones, x-10 cameras, who knows what else...

Good luck bro - I feel your pain..

New Member

Re: Realworld Wireless speed and errors

The 1.0 rates where my last ditch effort to try everything, as was guest mode. I actually had the a radio off during my tests, just turned it back on.

I've killed all devices that emmit anything around the ap's. No microwaves. No B devices. Didn't know ethereal changed it's name, had me stumped there for a minute, thank you google, I'll try that tomorrow. I've tried with two known good cards and the ap plugged straight into a cleanly reset firewall with nothing else on it. I killed all speeds but 54 and still bad.

I will lower the power tomorrow and see what happens. If that doesn't fix it I may get Cisco to RMA one of them and see what happens. I may also take the ap, two laptops and a couple of cards to the middle of nowhere (Wyoming has a lot of that) with one of my larger ups' and see what happens. :)

No way am I going to get the board to approve buying Cognio or any of it's brethren, tried that last year with wildpackets, non-profit with donated Cisco stuff.

Re: Realworld Wireless speed and errors

Netstumbler interoperability with certain cards cause netstumbler to report a noise of -100 and never changes.. This is not the true reading and should not be used to judge an environment.

Also should note the command 'show dot11 ass all'.. To get what the AP is seeing in terms of SNR and sig strength.

New Member

Re: Realworld Wireless speed and errors

I doubt this has anything to do with interference. Reset your AP back to its defaults, then setup the AP with nothing else but Open Authentication. Do not use any type of encryption (WPA can sometimes cause weird behavior) Then run your tests and see if you get better speeds.

New Member

Re: Realworld Wireless speed and errors

I got called out of town on business, I'll definately try all of these suggestions when I get back. Thanks!

Cisco Employee

Re: Realworld Wireless speed and errors

There have been some reports of other wireless products "bending the 802.11 rules" that make them act as bad 802.11 neighbors. This is not in relation to interference, but rather inflating the duration values within the 802.11 frame. So, unfortunately, it's not always just as easy as looking at signal/interference.

Do you have an 802.11a client adapter? If so, you can attempt to use that for access. At the very least, if this does fix your issue, it would eliminate a configuration problem (replicate your configuration from the do0 radio to do1).

I'm not saying this is a solution, but rather a method to further isolate the problem.

If you experience the same throughput over the 802.11a interface, there is something else at hand...

New Member

Re: Realworld Wireless speed and errors

I do just happen to have an orinoco gold laying around. I'll try it on A and see what happens. Thanks!

New Member

Re: Realworld Wireless speed and errors

I finally got it figured out. I dropped power on both radios to 14dBm and set client power local to enable and limit client power to 11dBm. I tried every combination and with it set like above I started getting 22.47Mbps from two of my NIC's, the others are a little slower but that's due to range and it's well over the 2Mbps I had been getting. I guess it was reflections. I now have another issue I will start a new post about.

Thank you guys so much for your ideas and input, you've been very helpful!

BTW: I still get alot of errors, is that just the nature of the beast?

Bronze

Re: Realworld Wireless speed and errors

Hey glad to hear it is getting better.

you should not be getting more than 2% errors in my opinion. anything more than that and there is still some tweaking to do.

14dBm is still 25mW-ish...how much real estate are these two AP's covering.

What I would do is determine how much space one AP can cover without ill effects and what power setting, antenna configuration, placement etc..that turns out to be.

with that information you can perform a site survey that is based on credible data and see how many AP's you need. You might need lower power and more AP's than you think.

New Member

Re: Realworld Wireless speed and errors

One is covering a two story 1700sq foot house/office, tri-level. One is covering a single story office building with about 20 small offices, a perfect square and the ap is in the middle. And two are covering two wings of another office with about 10 offices per wing arranged like an H.

If I drop the power, I start to quickly loose throughput to my farther away devices which are currently getting almost 18Mbps, I think I'm at the optimal power for them. Coverage is actually perfect, it just barely reaches outside the building and I can get 18Mbps or greater anywhere in the buildings. Kinda strange 14dBm worked the same in all buildings though....The house is wood frame, two of the offices are mostly cinderblock and brick, hence the two ap's in the H shaped office.

I don't know about the errors, what else can I tweak? The configs are default with wpa-ent enabled at this point and the lower power settings. I guess if I get 22Mbps I can't really complain even if there are a bunch of errors right? There is no latency to the rest of my network and nothing seems to be corrupting during file transfers.

Bronze

Re: Realworld Wireless speed and errors

Ok how is this for an educated guess -

You are looking at coverage and throughput as your main objectives, which is good but i haven't seen anything so far regarding signal quality (except for ScottMac in the second post.

The question here should be " at what signal strength / signal quality do I have when I have achieved my other two goals?"

Data is very forgiving since if a packet doesn't make it to the destination the first time it gets re-sent until it does. Same in regular networking as wireless.

If you had that many errors on a switch, a big red bell would be going off in your head.

Sure, everything works but it is not very efficient. If you are ok with this, that is a choice you have to make, because the answer is going to be spending more money on infrastructure.

You should have no less (in my opinion) no less than a 20dB fade margin to pass data sucessfully. Some people would say 25 but hey..

I would be looking at what my signal strength is in dBm (please, percent means NOTHING) and the quality of that signal with the handy Cisco Site Survey tool and a continuous ping from the AP and then the switch and then beyond the switch to something else.

You also need to consider the number of users per AP as this is also a cause for errors.

Obviously you are probably going slower than you need to be - but if no one is complaining...just so you know the more users you add the worse it will get.

New Member

Re: Realworld Wireless speed and errors

Should I be getting better than 18-22Mbps? I only have 4-8 people connecting per ap at a time, sometimes less. My switch's aren't getting any errors at all, so it's only on the radio side.

I don't care how many errors I get as long as the data gets to where it's going fast enough, latency is virtually non-existant so I'm not worried about that either. I know that may sound ineffecient, but as long as I don't have a lot of users I don't think it will matter. Please correct me if I'm wrong though. I will mess around with my client devices and see what dB they show in various situations.

Bronze

Re: Realworld Wireless speed and errors

It all depends on your environment and how close the users are to the radio. A survey would answer that question, I have no idea.

At some point you have to make peace with it and either accept what you get or run cable.

Sounds like you are at least better than you were and thats good...

New Member

Re: Realworld Wireless speed and errors

What type of laptops are they? I have had issues with the new dell latitude 620's with the intel cards. It sounds goofy, but if you turn the power setting down in the wireless card properties to 3/4, the connection improves 10 fold. It took me many days of troubleshooting before I came across an article on Intels site.

New Member

Re: Realworld Wireless speed and errors

I actually have one 620 on my network, it's always had issues with my AP's, I did drop the power and it works better, but at times it won't even SEE the AP's. Hoping Intel has an update soon that will improve things. My other systems are working great now.

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