cisco br1310 p2p link saturation over more connections

Unanswered Question
Mar 20th, 2010


We have a p2p link with 2 x AIR-BR1310G and 2 x AIR-ANT1949 yagi. We connect 2 sites over 2km. When we put around 20 PCs over the wireless link connecting to a server the link looks stable but when we try to connect all the remaining 200 PCs the link saturates very quickly. Each PC consumes around 20kbps so to speak all the 220 PCs take around 2.5Mbps.

The link stats give us the following:

- signal strength on both sides aroung -62dB

- SNR on one end 28-32dB and on the other 18-22dB

- we already changed the polarization of the Yagi antennas from vertical to horizontal. it improoved the SNR on one end from 12-16dB to 18-22dB.

- we are on CH 1, best stats,

- bandwidth available 18-24Mbps

So when we connect all the 220 PCs over the link to the server, the PING responses from the server go up very quickly and eventually become unaccaptable. We also get much packets loss, every 20th packet is lost. What could be causing this problem? IOS software version? We've been using 12.3(8)JEA2 and JEA3. We checked the Ethernet port stats on both ends and no errors, same on the switches. However on the TX of the Dot0  ports we have lots of errors on the end with lower SNR.

Thanks a lot for your input.

I have this problem too.
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dgohain Sun, 04/04/2010 - 23:31

if you have concatenation configured on the bridges disable them

remi-reszka Mon, 04/05/2010 - 07:59

hi there and thanks for response. how would that affect the over all performance of the wireless link? I have indeed concatenation configured and only on the root bridge. do you think this affects the wireless link when there are many connections over it? thanks

dgohain Mon, 04/05/2010 - 13:40


Cocatenation sometimes causes droppping or slow connectivity because it waits to concatenates small packets into a large one and than transfer the packet.


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