Tuesday, August 19, 2008

SonicPoint Access Points losing Connections...Part 1

Part 1:
Over the past few weeks I have started having some serious issues in my sonicpoint deployment. Last budget cycle we purchased six sonicwall sonicpoint G's for central management and high quality wireless that will also provide good security at the same time. Since we recently deployed a sonicwall Pro 3060 for our main peremiter security I figured it was a no-brainer to get sonicpoints that could easily be managed from the sonicwall appliance.

Unfortunately the SSID beacons started dropping like crazy and it seemed that even a simple reset and reboot of the devices wouldn't even bring them back up. Basically it would take several hours of constant rebooting and removing the device from the console administrator and then re syncing them to get them back online.

So I did a little research and came to a couple of interesting thoughts. It seems that a lot of major universities have been having issues with wireless access points and firewalls coming to a complete halt because of the number of IPhone users that were hitting the access points. A few articles pointed to the IPhone wireless devices being at fault. But no one really seemed to have a concrete fix. So I turned to the awesome church IT community and talked with my friends about my issues. Some seem so irritated with sonicpoints all together that they were about to sell them on eBay. Others had excellent success with them and talked about how rock solid there wireless networks were even in a full congregation using it as well as in a full house conference.

So was I having a vendor issue... or is it another underlying issue that deserves another look? After all when I first went to sonicwall appliances it seemed harder than Cisco device configs... but it wasn't the devices.. its just a new technology that needs another look.

Which brings me to another interesting thought. Maybe it really isn't the IPhone or the sonicwallw? It could be just the number of users that are concurrently connected at the same time. As well as channel issues. After more brain storming this evening I'm almost confident that it is channel oriented.

In an environment where you have numerous wireless access points that all have the same SSIDs they tend to overlap much like an FM radio station does when you are between two stations. Example when your between two FM stations and you hear both channels trying to break through at the same time. This is the same type of situation you have when your using RF devices like wireless access points.

Another issue is other Access Points in your environment and even access points at neighboring businesses. Those access points may have the same channels.

Possible solution? This week I am going to try and bring all of the Channels down and try the following:

Adjust the minimum data rate at which the SonicPoint will send data to clients. Setting a minimum data rate of 24mbps, for example, will cause clients with an 11mbps connection to be ignored.
Adjust the beacon intervals for my SSID's. This can help speed up handoffs between access points when users are mobile and when clients are initially connecting.

According to SonicWall selecting AutoChannel will usually provide adequate performance for most situations, a deployment with many access points in close proximity to each other might warrant manual channel selection. Channels 1, 6, and 11 are the non-overlapping channels in the 2.4GHz range, and should be used for access points in close quarters. Manual channel selection adds a bit more complexity in subinterface and provisioning because I will need to carefully plan out and provision three distinct SonicPoint groups, one for each channel. --ick

So i'll focus on these ideas and report back with my conclutions :)

1 comment:

Brian said...

I would love to hear how this turns out for you.. I'm having very similar issues, and am going to try your suggestions..