P2MP design

Unanswered Question
Apr 15th, 2008

I am in the process of designing a Wireless solution to connect 2 separate buildings that are hard to wire. In the design, I have a central building that will home all of the networking devices including, wireless bridge, and the gateway. This is the building where I will put the central bridge and a directional antanna. My question is, how should I connect the other 2 buildings to this central building?


Would it be with one cental bridge and antanaa to connect the other 2 buildings (P2MP)? Would this allow full-duplex for each connection?


Would it be with 2 cental bridges and 2 directional antannas to connect to the 2 separate buildings (P-to-P) to allow full-duplex for each connection?


Thanks for the prompt response,

sK

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bcolvin Tue, 04/15/2008 - 11:37


First whether you have two roots with separate links to each building or or one root for both non-roots will be determined by the bandwidth required over the links. The other consideration is will both non-root AP's be covered by a single directional antenna.


Second the Cisco 1200, 1300 and 1400 AP radios all operate in half-duplex mode.


Hope this helps


Bill



skhirbash Tue, 04/15/2008 - 12:28

So, which one of the following scenarios provides best preformance considering that VoIP will be implemented?


- 1 root bridge with one directional antenna(Central bldg) connecting 2 non-root bridges(2 directional antennas).

- 1 root bridge with 2 directional antennas (Central bldg)connecting 2 non-root bridges(2 directional antennas).

- or 1 root bridge, 1 non-root bridge with 2 directional antennas (Central bldg) connecting 2 non-root bridges(2 directional antennas)


In all scenarios, all duplex mode will operate in half-duplex?



bcolvin Tue, 04/15/2008 - 12:58

Okay


now some info to work with


best configuration, 2 root bridges each with unique SSID and a single directional antenna. one non-root in each remote location with a directional antenna.

a second antenna is not needed as multipath is not an issue with bridges.


In all scenarios the radios operate in half-duplex. the radio cannot transmit and recieve simultaneously.



the bridges will require clear line of sight, also the distance between root and non-root is a factor to consider in you design. check these links for details.


http://www.cisco.com/en/US/tech/tk722/tk809/technologies_configuration_example09186a008058f53e.shtml


http://www.cisco.com/en/US/products/hw/wireless/ps458/products_tech_note09186a008009459b.shtml


There is much more information available just follow the links in the abpve documents.


Good luck with your project


Bill

skhirbash Tue, 04/15/2008 - 13:11

Are there any bridges/antennas that would operate in full-duplex? Half-duplex will present issues for VoIP implementation.


Thanks,

sK

bcolvin Tue, 04/15/2008 - 13:23

Yes there are Proxim.com has several models that will probably meet your requirements. there are also other manufactures of theis equipment a web search should find them. just remember these products are ususlly much more expensive than the Cisco 2.4 and 5.8 products but they do offer 100mbit full duplex.


HTH


Bill

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