Cisco BR-350 Bridge setup -- Any Help with Error Messages - Associations?? ,, thanks

Hi all,

I'm using 2 cisco 350 radios on a wireless link about 2mi in length.

I've got the radio, 40' LMR400, 24dbi grid dish on each end of the link. The power on each radio is set at 100 mw. The radios are set as root and non-root w/o clients.

I can see each antenna from the other antenna with field glasses so I've got no obstructions between the links. One antenna is mounted at

60' and the other antenna is mounted at 40'. The antennas are horizontally polarized.

I've checked the channels and am using channel 9, which shows NO radios on that channel. I've done this with netstumbler. I've checked this by driving between the two points and watching the laptop for radios. Also to be sure I connected a PCMCIA card in the laptop to each antenna and checked for radios showing up this way also. So i'm pretty sure that I've got no other radios on channel 9.

The link tests show about a 98% signal test at all times i've checked it.

However, the log shows that the non-root radio without clients associates and dis-associates itself from the root radio about every

3-5 minutes.

I can supply more information about this link if needed.

Thanks for the read and possible help,

Bob Smith

Robert Smith Consulting Fort Bragg, Califonria

Reply to
Bob Smith
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Bob Smith hath wroth:

Sounds good. TX power = +20 dBm TX coax loss = 4dB TX ant gain = 24dBi Distance = 2 miles RX ant gain = 24dBi RX coax loss = 4dB RX sens = -84 dBm (at 12 Mbits/sec) Fade margin = unknown |

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fade margin is 33.8dB. That's more than enough.

Depending on what speed you are selling, you might consider dropping the xmit power to a bit less than maximum.

Fresnel zone incursion? You need 27ft clearance at midpoint. Are your antennas both more than 27ft off the ground? Any debris within

27ft of the line of sight at midpoint?

Yech. Ch 9 will get interference from both 6 and 11 as well as the other channels in between. Channels are 5 MHz wide. 802.11 is about

25MHz wide. Try to stay on 1, 6, and 11, even if occupied.

Netstumbler only picks up access points that respond to probe requests. They don't see client radios, AP's with SSID off, proprietary protocols (frequency hoppers), etc. At least use Kismet, which will see client radios and bridges. Borrow a spectrum analyzer and do some sniffing for non-802.11 junk. A friend recently found a local company doing injection molding in a small industrial park. They had a very leaky microwave oven setup as a a plastic pre-heater to remove the moisture before molding/casting. I've now found 3 over powered 802.11 amplifiers that were generating more pollution than communication.

Laundry list of potential sources of crud:

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OK, that's more than sufficiently strong. What about S/N ratio? If it's interference, it should be going up and down.

WPA re-keying interval? Try it temporarily without encryption and see if the problem goes away.

Contour profile using Radio-Mobile? (Never mind).

Reply to
Jeff Liebermann

This is what I figured also....

I haven't had that much experience with Cisco radios but the associated/dis-associate problem could be a radio. I was watching the root radio and I think I was seeing a boot/reboot happen intermittantly. All the lites would turn RED then all out, then the radio would start to work. This is a city system and the bad thing about it is that they don't have any spare radios that I could substitute in to see if it's the radio.

I've tried setting the speeds from 1mb to 11mb & auto. The speed doesn't seem to help the situation

The Fresnel zone looks clean with field glasses. No trees or buildings are in the way.

The local computer store has started putting up hot spots. There is one about 2000' from the Root Radio. The radio they are using is a tranzeo panel pointed South. My antenna is pointed NW using netstumbler I see the tranzeo radio signal strength varying from

10 to 20. it's about 60 degrees angle from the center of the 24dbi grid feed.

On the same tower I have another cisco radio on channel one pointed

180 degrees direction( see below)

powered 802.11 amplifiers that were generating more pollution than

I've also used Kismet and seen nothing in the area.. The non-root radio has no buildings arround it for at least a mile. The root radio does have the hotspot radio shown above.

I wish there was a way to see SNR.. I don't see how to do this with the 350 radio. They just have antenna alignment and signal strength

However, the log shows that the non-root radio without clients

I have turned the encryption off, and am broadcasting the SSID

thanks jeff, maybe the above will help explain it a little be more..

Bob

Robert Smith Consulting Fort Bragg, Ca NA6T

Reply to
Bob Smith

That sure sounds like an unscheduled reboot. Anything in the logs? |

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you think it's crashing, try the usual reset to defaults and reload all the settings. If you're really adventureous, reflash with the latest firmware.

There are several AIR-BR350 radios on eBay for $250 to $400 ea.

Did you try different channels? It's probably not the signal strength with means that speed (and corresponding rx sensitivity) probably are not part of the problem.

You didn't answer my question. Are your antennas more than about 27ft off the ground? If not, the ground is in the Fresnel zone.

Don't worry about it. The 24dBi dish antennas have a -3dB beamwidth of about 7 degrees. You'll never hear anything coming from the side or back. What you will hear is anything that's inline with the line of sight (in both directions). Are there any radio towers along the line of sight?

That might cause a problem when they're that close. Just stay away from channel 1 and you'll probably be fine.

I'm fairly sure it's not an RF issue, but a spectrum analyzer might show some non-802.11 interference.

I think it's in there somewhere. Maybe on the IOS command line. Most probably can be extracted using an SNMP MIB browser. MIB list: | ftp://ftp-sj.cisco.com/pub/mibs/supportlists/c350/c350-non-ios-supportlist.html I don't have a BR350 handy to figure out the appropriate OID or incantation.

BR350 pages: |

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Reply to
Jeff Liebermann

ftp://ftp-sj.cisco.com/pub/mibs/supportlists/c350/c350-non-ios-supportlist.html

Wrong URL. For the BR350 MIB's, see: | ftp://ftp-sj.cisco.com/pub/mibs/supportlists/c350/c350-supportlist.html

The SNR is in the 802.11 Interface MIB at: | ftp://ftp.cisco.com/pub/mibs/v2/CISCO-DOT11-IF-MIB.my Search the document for "SNR".

Use a MIB browser to extract the numbers. I suggest GetIF 2.3.1 from: |

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the program. Drop whatever MIB files you need into: c:\\program files\\getif 2.3.1\\mibs\\ directory. Erase the file named ".index". Getif will recreate it every time it starts. When you add (or remove) any of the MIB files, erase it again. Yeah, I know it's dumb but I didn't write this thing. Operation of the program is "obvious" (which means read the help and don't bug me). Good luck.

Reply to
Jeff Liebermann

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