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Pairing 2 sets of bridges on one LAN for increased bandwidth

Hope I'm not being too blonde here...

We're a church and school (read: no money for real sophistication) currently connecting a LAN that spans two buildings with two simple D-Link 2200 APs (802.11g 108Mbps) operating in bridge mode. The two bridges are about 50 feet apart, straight line-of-sight and the performance has been generally more than adequate for our needs. The buildings are separated by a city side street so there's no feasible way to run wire. It's a BIG city and getting approval to do this would be a futile effort.

The majority of the current traffic across this bridge is Internet surfing from building A to and from a T1 in building B. Only rarely have the individual computers in either building needed to cross the bridge to each other, so to speak. That's about to change, however, and

5 administration computers in building B are now going to regularly access a database on the server in building A. The users in building A also need access to this same database. The program to manage this DB has no inherent means of keeping two individual installations evergreen so we have to find a way for both buildings to efficiently access this single file.

We're concerned about a traffic slowdown and were wondering what options there might be to increasing the throughput across this street. One thought was to keep the Internet traffic that originates in building A to the current bridge, and add another another 2 DLinks that would provide a second bridge that would be specifically dedicated to those 5 admin computers. We feel 802.11n is just too far away.

Is it even possible or feasible to run 2 pairs of bridge devices in this scenario or are we just brainstorming ourselves into stupidity? What brought up this concept was a fond recollection of pairing two dial-up modems for blazing speed not so many years go. ;)

To further complicate things we're also toying with the idea of adding yet one more DLink in a 3rd building, and set up point-to-multi-point on the existing bridge so that third building can also access the T1. But by far the bigger issue is getting a dedicated pipe for those 5 admin computers to the server across the street.

Any other recommendations for separating/increasing the throughput in this situation would be very welcome.

Thanks, ~Jacy

Reply to
jacy77
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You don't mention what model hardware you are using.. but you can use quality of service to prioritise traffic over the bridge. You'd need a bridge/router that does this.. eg: Linksys WRT54GL - one at each end with DD-WRT firmware - this has excellent QOS settings.

You could set file and print sharing to max and "other traffic" to a lesser priority. (or break down the traffic by protocol eg: http - lowest)

That way when the link gets saturated with traffic you are guaranteed to get your DB running at optimum with your "other" traffic resigned to waiting for a slot.

Anyone else add to this ?

Doz

Reply to
Doz

snipped-for-privacy@gmail.com hath wroth:

I'll assume a DWL-2000AP

Please measure your thruput and convince me that it's adequate. At

50ft and presumeably with better than stock antennas, you should at least get a 54Mbits/sec connection, which will give about 25Mbits/sec throuput. Just copy a big file and use a stopwatch to estimate the thruput. Do it in both directions. However, if you dont' have line of sight, or are using junk antennas, the speed will be lower.

Go through the sewers with fiber. There are lots of other pipes available under a street. Just look for them in the manholes. You can also piggyback on the CATV if there's a common cable.

Also, check how well the program responds to data loss and disconnects. Wireless is not like wired ethernet in that it will have fades, higher packet loss, disconnects, and such. I've seen far too many database engines that blow up with the slightest hickup.

You should be getting 25Mbits/sec thruput with your wireless. A wired ethernet 10baseT-HDX will do perhaps 7Mbit/sec. 100baseTX-FDX will do about 80Mbits/sec. You're already in the ballpark.

Barf. Yeah, it can be done and can be made to work. The traffic load will NOT magically distribute itself between the two wireless links. You'll need some manner of load balancer or just live with seperate paths for seperate connections. I don't see if justified unless you have *SUSTAINED* high traffic through the wireless slink.

Both. It is possible to do this and yes, it's a dumb idea.

Yeah, but that was with a multilink protocol that required the cooperation of the ISP. It can't be done with off the shelf, bottom of the line, wireless hardware. See:

formatting link
load balancers.

Three options depending on line of sight:

  1. WDS (wireless distribution service) network.
  2. Point to Multipoint bridge network. I think your DWL-2200AP supports this:
    formatting link
    PtMP is supported.
  3. Seperate link between 3rd building and whatever. It all depends on line of sight and what you are connecting.

No, the real issue is performance. Estimate how much data you're gonna move and how fast. Measure what you have now. Then decide if you actually need more bandwidth. I really doubt it.

Reply to
Jeff Liebermann

Put the admin computers on a different subnet and use a different wifi link. That way you'll keep their traffic separate and, in theory, give better performance. The trick being in structuring your wired setups such that it's possible to have these machines on a different subnet and/or VLAN. I designed and ran a campus-wide network doing just this, but using fibre between the buildings. Worked quite well to have the traffic segregated, both from a performance AND a security perspective.

It all depends on what you've got on the in-building networking side of things. What switches and routers are in use now?

-Bill Kearney

Reply to
Bill Kearney

On Wed, 19 Jul 2006 13:34:56 -0400, "Bill Kearney" wrote in :

Good suggestion. Make sure the two wireless networks are on different channels with minimal overlap (1, 6, 11). Check first for possible interference, although directional antennas may be able to overcome it.

Reply to
John Navas

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