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350 Bridge Sporadic Performance

Our institution currently has a point to point bridge setup using aironet 350 bridges connecting a remote campus (about 400 pc's) to our main campus. The bridges are no further than 200 yards apart. All internet traffic for the remote location is routed over the wireless bridge to our main campus. A problem we're encountering is sporadic performance issues from our remote location throughout the week, such as slow logins to the network (we're a novell shop), slow internet performance, and slow performace for a network application which is housed on a server at our main campus. When the performace issues arise we notice that the ping times to a router on our remote location fluctuates from 3ms to over 500ms. We're also noticing high CRC errors on both bridges as well as high retry counts. We've updated the frimware on both bridges to 12.03T, tried different frequency's, and even set the bridges to their factory defaults, but we're still seeing performace issues. Is it normal to have the milliseconds fluctuate so high? Is it possible we're seeing congestion on the wireless bridge link? If it is congeston, is 400 pc's too much load on the wirelss bridge link? During the weekend and off hours the ping times are a steady 3 to 5 ms.

Cisco Employee

Re: 350 Bridge Sporadic Performance

It sounds like you have both a combination of interference and congestion

CRC errors often mean interference

If you have congetsion you will see hold offs and discard.

Often interference will compound the effect of congestion as the interference will be seen as another station transmitting so the radio will hold off then try again this will cause the buffers to over flow and discard the packets

Has this happened since installation or a new problem ?

what did you site survey show in terms of other devices and possible sources of interference ?? What did it show in terms of obstacales that maybe in the line of sight or fresnel zone ??

What average results do you get for the channel activity test and antenna alignent tests ??

As to 400 PC's being too many that is hard to say as what realy matters is the amount of traffic you are trying to send across the link, what is your peak and average bandwidth utilization for this link ?

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