Intermittent slowdowns over WDS network

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withersteen
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Joined: 10 Nov 2008
Posts: 7

PostPosted: Mon Aug 06, 2012 4:09    Post subject: Intermittent slowdowns over WDS network Reply with quote
I run a small WDS municipal Wi-Fi system. I am having intermittent network slowdown issues, which seem to be rooted in the wireless network.

The internet source is a DSL modem in bridge mode connected to a Mikrotik router. Connected to the router is an 8 port unmanaged switch. To this switch are connected several computers and a WRT54g-TM access point which is acting as a WDS host/main. There are 4 other WDS nodes connecting back, all of which are WRT54g-TM's. All are running DD-WRT v24-sp2 (12/24/10) std-special (SVN revision 15962).

All of the WDS nodes accept wireless clients. The fourth WDS node makes another hop over a hill to serve a 5th WDS node, which also accepts wireless clients.

Also connecting to the main WDS host are several WRT54g's in Client Bridge mode. One of these Client Bridges has a 20 port unmanaged switch attached, which serves about 15 computers.

Generally when pinging across the wireless portion of the network, I get single digit reply times, with the occasional 2 or 3 digit responses. Every once in a while, say every 15-30 minutes, there is a considerable slowdown, down to 4 digit reply times with timeouts abounding. Then, seemingly, things calm down and ping times revert to single/double digits.

I would appreciate any insight into this issue...
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buddee
DD-WRT Guru


Joined: 06 Feb 2010
Posts: 7401
Location: Little Rock

PostPosted: Tue Aug 07, 2012 0:29    Post subject: Reply with quote
IMHO you have to many nodes on a G connection, because wireless is a shared medium, meaning the more wireless connected nodes or clients you have, the less wireless bandwidth you'll have available at all. And with a G connection, you are looking at 24mbps shared amongst many nodes, that can shrink down pretty fast with as many nodes as you have connected. Just my opinion..
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withersteen
DD-WRT Novice


Joined: 10 Nov 2008
Posts: 7

PostPosted: Thu Aug 09, 2012 0:04    Post subject: Reply with quote
Fair enough. I am trying to understand a good upgrade route.

-Should I attempt to purchase a Gateworks Laguna, for instance, to replace the main WDS Host? Would upgrading just this critical node give any performance boost?

-Or, would replacement of all the WDS nodes with Dual-band routers/access points be better? Using an N-mode as the backhaul, with G available for clients?
buddee
DD-WRT Guru


Joined: 06 Feb 2010
Posts: 7401
Location: Little Rock

PostPosted: Thu Aug 09, 2012 13:41    Post subject: Reply with quote
I really cannot comment on the laguna gateworks hardware, i don't have any. From reading the specs though, it looks very worthy. But one thing for sure you would need to keep in mind is that whatever you get, make sure the wireless chips match up, i've read alot of mixed reviews regarding WDS and mixing of chips, some say it works, others say it doesn't work for them and so on, so i'd keep the chip choice either all broadcom or all atheros etc.

In your scenario here, i would atleast upgrade to N units - so as to have more wireless bandwidth to share amongst your nodes and it shouldn't matter if they would be dual band units or not, though dual band/dual radio units wouldn't be a bad choice. With the dual band/dual radio unit, you could use either the 2.4 or 5Ghz radio for the WDS backhaul link to each other, and use the other radio in the unit for the clients to connect to, and it'd be alot more efficient in this manner, because it wouldn't have to rely on one radio in each unit to do all the work (keeping the backhauls and serving wireless clients).

Also to note, this is just my opinion, i haven't ever linked that many nodes in a WDS setup to fully confirm if it would be better or not, the most units i have had linked in a WDS setup was 3 N units, and it worked quite a bit better than when i had 3 G routers connected together.

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