Advice, comments - please

Hi everyone

I'm looking for some advice on the following configuration. We are planning on connecting a number of sites in a sort of star configuration - one of the sites is on a hill, and is visible from all the others.

Base site:
1. Borg 8Slot WaveGuide - http://shop.borg.co.nz/product_info.php?cP...&products_id=28
2. (optional) 500mw Booster for 2.4Ghz - http://shop.borg.co.nz/product_info.php?pr...products_id=541
3. 802.11g AP

Remote sites:
1. Borg 19db Parabolic Grid - http://shop.borg.co.nz/product_info.php?products_id=91
2. 802.11b/g PCI card

Our remote sites will range from 1 to 3.5 km. The questions that we need answered (or URL references to) are:

1. Do you think our selected configuration will work?
2. Do you think we need the optional booster?
3. Is it work spending the extra money to get the "g" AP. Will it actually be any faster / more reliable (over our distances)?

Any advice would be much appreciated! It'd be a shame to go and buy all this stuff - only to find it doesn't work. Also, if you can recommend any good sites that document the kind of equipment they're using (as a good example for us - and so we can convince the 'accounts' dept).

Thanks

Nigel Ramsay.

Location: Northern Suburbs, Wellington

Well at only 3.5kms i would doubt you would need a booster, though the owner of borg may offer otherwise!!

All the gear sounds fine and should work, it is a matter of how data you want to put through as to whether you use b or g. There is a point to note though if you use b gear on a g AP then the AP will default to b speeds. I have have yet to have this confirmed from actual results but it is a common rumour.


Wookie

We're building the network from scratch.

I guess my question about the whole b/g thing was "at a distance of 3.5 km, can I really expect to be able to achieve >11Mbps speeds".

Nigel,

I would tend to agree with Wookie, You should be able to do this without using the 500mw AP.
As for Range/Speed. This often depends on the terrain and foliage in the surrounding area. however in Wellington we have a client that is doing a shoot over from one side of the harboujr to the other and getining and average of 4Mb connects. he is using a 24dBi Grid and a Borg Twinfire.

Depending on how many clients you intend to hook on to the network you could go for a Mesh AP system with a 200mw card in it, alternativeley if you are only going to have a handfull of clients then an AP woukd be the way to go. We have some more 200mw AP's due in in a couple of weeks.

Cool. now that is something that never occured to me until wookie printed it. B or G / BORG Anyway back from the giggle. B tends to offer more stability than G. If you have clients that connect using B then this will drag the network down to B speed. However it is handy to have G. G also has a lower power rating and is more noisy.
We may be getting some A,B,G AP's with the next shipment that are capable of up to 108Mb but they are not exactly cheap.
from what i understand they allow you to use A and G at the same time but will depend on the quality of the link.

If it was not allready obvious I run Borg

Regards
Andrew Hooper

depending on the AP you should be able to use 11a and 11b/g at the same time, most have separate radios for a and b/g. I know with my unit I normally use 11a around home and autoroam onto 11b as I get further away (requires a a/b pc card as well).

11b and 11g will work together, but you will have to make a comprimise on either the b or g throughput. only 1 11b device associated or even near a 11g AP will cause this.

11g users a different preamble to 11b and as such 11b traffic can't see 11g traffic without help. 11g will wait if 11b is transmitting, 11b wont wait. A collision occurs and both streams back off after completely trasmittiing the packets. 11g has a shorter contention back off than 11b and so will often get talked ove the top of by 11b after a collision. In this scenario 11g traffic really suffers.

To remidy this you need to turn "protection" on on the AP. This then makes the AP reserve the medium using a 11b PHY CTS to Self command. This gives 11g the medium by flowcontrolling the 11b traffic. Problem is now 11g gets lots of bandwidth, the 11b traffic comprimsed. Also as 11g traffic has to send a 11b CTS comaand this is done at the "LOWER" 11b data rates (often 1Mbps) so comprising all traffic by chewing up bandwitdth for control messages.

Basically either have all 11g devices, keep 11b devices well away or use 11a

Just bear in mind bonding of 11a amd 11b channels to get 108MB is a FCC standard only and as such only applies to North America. NZ is alligned with ETSI standards out of europe and channel bonding is not allowed. Also ETSI uses slightly different frequencies to FCC

For 11a
FCC uses 5.15-5.25Ghz, 5.25-5.35Ghz and 5.725-5.825Ghz.

Etsi uses 5.15-5.25Ghz, 5.25-5.35Ghz and 5.470-5.725Ghz.

Until the 802.11d standard (autosensing of country settings) comes out on APs and cards you will get potential for performance problems with mixing FCC and ETSI gear.. Most gear does allow you to set country settings to set it up for NZ
The 2.4 and 5 bands in NZ are unlicensed but not un regulated.