Will addining another SM improve performance?

I have a site that is remote that is connecting via BH’s to a site with a SM. If I add another SM will it increase their performance in any way?
Current config
[remote site] BH---------------BH[site]SM ----------------[AP]
Proposed config
[remote site] BH---------------BH[site]-SMx2 ----------------[AP]

What kind of performance you want to improove? what kind and how much trafic do you have?
I would put or make advantage the ap.

Where is the feed to the Internet?

It is behind the AP.

I assume that you have a customer with two locations connected with BH’s to extend their LAN, and you are providing IP to the first site through the SM?

Are you using standard or Advantage AP’s and SM’s?

If you have an Advantage AP, and standard SM’s you can get some additional throughput by doubling up on the SM’s, or using an Advantage SM.

If you have a standard AP, then doubling the SM’s will not gain much.

It is an Advantage AP, and yes this is all to connect the company not for internet services.

Then an Advantage SM would be the way to go. The Advantage AP/SM will auto-negotiate the rate from 2X to 1X in the event of interference rather than drop the link altogether. At 2X you will get 14M aggregate - same as the BH’s.

Otherwise you could double up on standard SM’s. We have had two SM’s on the same post connected to the same AP with no physical separation and it worked flawlessly. One link even had Vonage and it was fine. You will need some type of load balancing router.

Is there any easy way to load balance a Dual Backhaul situation?

We have a tower 15 miles away from NOC that is getting pretty critical for us. (it then feeds 6 other towerss). We have a Moto BH and want to connect a 2nd BH (of Moto or other brand) as a load-shared and/or backup link.

Any field proven suggestions?


I would recommend going with OFDM 30M. Once you hit the wall with that, upgrade it to 60M.

Not sure how you would load balance all that traffic as typically load balancing is done with a router. There may be some way, but I don’t know what it is.

The need is just as much for a redundant solution as much as it is capacity. (if not more).


Couldn’t you set one backhaul link to download at zero and the other at 100%?

two BHs each plugged into a standard environment is like plugging two wires into two stiches. (bad thing happen) :slight_smile:

There needs to be some “protocol” to manage it. I am looking to find someone who has very successfully got this figured out.


I thought thats what BAM was for?

No. BAM doesnt deal with that kind of network topology stuff.

Couldn’t you plug the BH’s into a managed switch that supports Spanning Tree Protocol? This would take care of your redundancy but it would not take care of load balancing.


This may be more of what you are looking for. This will allow you to have 2 backhauls plugged into a managed switches at point A and point B.

When properly configured the 2 ports that the backhauls are plugged into act as one port.


Very cool, thanks!

Yes, this gets me on the right track. We are going to give it a shot with the 3com 3300 XM’s that we are using. The port trunking feature appearks to give (according to docs) the combination of both reduancy and load-balancing.

Thanks guys!


Just remember to keep the links on the same vendor platform for the switches, ex: asus, cisco, 3com, dlink… This will help, as some vendors used to use there own protocal to do this, like cisco.

what about 2 sm’s backhauling from two different sites? one sm on each site? that should be possible. I have some locactions where i can see 4-5 of my different sites :stuck_out_tongue: