Hi,
Hoping someone might have insight on the problem below...
I have had a short-distance (about 6km) link running for pretty much a year now, and recently I notice that the reported Tx/Rx bit rate is regularly, but briefly (few seconds) dropping from max (54Mbps) right down to 6Mbps and then back up again. Receive level remains steady at around -60 dBm at each end (Tx level around 6dBm at each end if I recall correctly). The problem is that packets get dropped when this happens. I'm using 30dBi parabolics at each end, so directivity should be good, but setting the bridge to scan mode revealed networks at;

5180 level -66 dBm (also picked this one up in Turbo mode)
5240 level -85 dBm
5745 level -88 dBm

I was running at 5200, but also tried 5280 and 5785, but with same results.

Do you think this is symptomatic of interference or a hardware fault? Or something else?

Many thanks if anyone can help!

We have a similar issue. One of my links is a 802.11b link with and MT AP on one end and an MT client on the other. Both have mini-PCI Prizm 802.11b cards in them. The AP has an omni antenna and the client has a 14 dbi roo. The are about 2.5 miles apart, but about 200 feet up on towers.

The client radio will report a 11mb/2mb TX/RX rate and will go up and down all the time. The AP will register 11mb for both most of the time, but it does jump around. The signal rate is at -66dbm the hole time. The rest of the clients on the AP register at 11mb almost all of the time. They are CB3’s do I do not really know what the CB3 things, just the MT.

Any ideas on why this is?

What I am not entirely clear about, is cause and effect; that is, the links in both our cases seem to be strong and steady (-60 dBm'ish receive level), so we do not think it is actual link quality. The question is, does the 'over-the-air' connection rate change for some reason (interference?) and therefore cause packet loss, or could packet loss for some other reason cause the MTs to think that packets are getting lost and therefore the link rate needs to be dropped? I'm not familiar enough with the protocols which determine how the MTs (or 802.11x in general) determine when and why to drop the data rate to know.

Done anyone have any insight on this?

We do not see any packet loss, but we do see derogation in speed.

We have this problem in both RF noisy areas and RF quite areas. We have one location that has about 20 clients all have under a -62 dBm and never had the drop out issue with the Routerboard and Prism PCIMIA card. I upgraded this area to 2.8.16 and bam could only keep about half the clients registered at a time and they came and went on a regular basis. I had to upgrade to the mini PCI prism card.

Try to run a scan and see if there is any new equipment in the area running on the same band. If there is try changing the channel. Weather will also affect throughput.

Hi all,
It turns out that our problem was most likely due to a virus on one of the hosts connected over the LOS - it was probably generating UDP-type traffic that was just saturating the link (in fact, probably saturating the customers LAN before it even reached the wireless link) and therefore causing his network to fall over, generate intermittent traffic and thus cause the reported Tx/Rx rates to fluctuate widely. Does this make sense?

Regarding scanning; I have a point-point link using 30dBi parabolics over about 6km, and even then, I can pick up four other networks at anything from -88 dBm up to -66 dBm. Not sure if they are coming in via the main antenna beam, sidelobes, through the box or pick up by the CAT-5 cross-site ethernet (using outdoor boxes). But they are all on different channels to me and I do not think they are actually causing me a problem.