Can i make 2 link point-to-point with one ap ?

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Apr 16th, 2009
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I wonder if i can connect 2 branch with one headqueater, the idea is out one ap1300 with 2 atennas ominidirections, each one to a brach with a ap.

pls help

Correct Answer by gamccall about 8 years 1 month ago

Correct. You can do a point-to-multipoint configuration using one omnidirectional antenna at your root bridge, but you cannot use two antennas on the same AP to establish two different links.

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gamccall Thu, 04/16/2009 - 12:23
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Yes. One root bridge at HQ with one omnidirectional antenna. A non-root bridge at each branch site with a directional antenna pointing at HQ.


With that said, the price difference for a fourth AP is actually not that much when you consider the overall costs of the project (installation, cabling, surveying, etc) and you may find you get better performance with 2 pairs of bridges than with a star topology.

andresfmg Thu, 04/16/2009 - 13:04
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hi

thanks for the answer,


The complete scenario is:

2 branch and a hq.

first brach 300 m distance to hq

second brach 3 km distance to hq

clear line view.


the idea is one ap 1300 in the hq with a omidirection atenna like AIRANT24120.


first brach with one ap 1300 and antenna AIR-ANT1949 for 300 m.

second brach with an ap 1300 and antennas AIRANT3338 for 3 km.



can be done like this or better put in the hq 2 antennas omnidirectional the same caracteristics like each brach.


any ideas, ??


gamccall Thu, 04/16/2009 - 14:48
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Take a look at the bridge distance calculator here:


http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps458/prod_technical_reference09186a00800a912a.xls


This shows us that, assuming a 12 dBi omni (such as the ANT24120) at your root, the 13.5dBi Yagi is complete overkill for a 300 meter link- you could get 54 megs with the 10 dBi Yagi or even the 8.5 dBi patch antenna.


On the other hand, even with the dish on the other side, you can't get a 54 mbps datarate over 3 km. Depending on your bandwidth requirements, a 36 meg link to the second branch may be acceptable... but remember that the link to the first branch is contending for the same channel, plus protocol overhead, so you're going to get less than half the nominal datarate for each link.


So, depending on your bandwidth requirements, you have several different options:


1) The star topology you described. Lowest bandwidth option since both links are on the same channel.


2) A pair of 1300s with 9dBi patch antennas for link 1, and another pair of 1300s with the built-in antenna option for the second link. Better than option 1: this gives you 54 megs on link 1 and 36 on link 2.


3) A pair of 1300s with 9dBi patch antennas for link 1, and a pair of 1400s with the built-in antenna or a pair of 1300s with dishes for link 2. This gives you 54 megs on each link.

andresfmg Fri, 04/17/2009 - 05:31
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supose i choose the second options u describe. Can i just get one ap1300 in the hq with 2 antenas directionals,

remember that the ap 1300 can put 2 antennas in the same radio 2.4 ghz.



gamccall Fri, 04/17/2009 - 06:30
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No. There are two antenna connections, but that's not two independent links. The second connector is only used for diversity.

andresfmg Fri, 04/17/2009 - 06:34
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so, i cant make 2 links in one ap 1300 with two antennas.

i have to boy 2 ap 1300 with one atenna directional each one.


Correct Answer
gamccall Fri, 04/17/2009 - 06:45
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Correct. You can do a point-to-multipoint configuration using one omnidirectional antenna at your root bridge, but you cannot use two antennas on the same AP to establish two different links.

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