high CRC error count when rates over 24 mbit enabled

RouterOS Wireless Networking
1

I’ve noticed an issue across all my MT-based towers… If I disable 36, 48 and 54mbit rates I get considerably more stable connections. Most of our clients are madwifi(ng) based, but I see this problem across all our clients.

It appears MT keeps trying to push the TX speed up beyond what the client/link can handle and not giving up and not falling back on retransmit. I see no packet loss when set to 1-24, but I see 5-8% packet loss and high ping times when set 1-54. It doesn’t seem to matter if the client has a -60 signal or a -80 signal, there will still be loss.

I use three different cards on the affected APs - Ubnt SR2’s, Senao 8602+, and Compex 200mW b/g cards. The effects occur with both omni and sector antenna equipped APs.

Anyone else seen this? Any advice?

Thanks!

2

Yep! Most of my APs are set to 24 because 36 thru 54 can’t keep that speed with any interference at all. Shorter 1 mile links seem to be ok but anything over 2 miles in the 2.4Ghz channels goes to shit. I do have some 5.8Ghz links that do ok up to 13 mile with 48 and 54.

3

All my APs are locked down at 24 as well, same reasons, I have a couple backhaul (ie. very directional 2.4ghz, and 5.8ghz ant) links running at 54mbit but I have trouble past 4 miles maintaining a 54mbit link due to interference in my area.