PtMP backhaul considerations

[valenti]

I have two primary POP sites. I should be multihomed with Internet coming in from both sides within a few months. I expect to build out to about 8 new grain legs this summer, feeding them from one or the other primary POP.

I'm used to thinking of these sites being connected with point to point backhauls, but seeing how close some of the sites are I'm leaning toward connecting them point to multipoint.

(these points are about 10 miles apart)

Internet source <> POP1 <> POP2 <> Internet souce

For example, from POP1 there are three legs to the northwest, at most 25 degrees apart, ranging from 2 to 7 miles. Would I be making a mistake in using an AP (24dBi Rootenna) at POP1 to connect all three sites in that direction?

At the new grain legs I planned on using a War2 + Rootenna for the connection back, plus a 2.4 omni to connect customers. I'm building out so close because of the trees. Maybe I will be pleasantly surprised, but I don't think 2.4GHz will offer 100% coverage at even 2 miles.

Long term I would hope to mesh all of these together with OLSR. I would be adding a second WAR2 then, and maybe also supporting 900MHz at some POPs.

Another example: the Internet connection to POP1 has yet another grain leg directly in line with it. Should I not use multipoint on this important link? Or if I do, should the AP side be at the Internet source or POP1?

(ummm, hope I'm not committing a faux pas by calling them Rootenna instead of Wartenna...)

[lonnie]

It is quite OK to build your backbone with p2mp EXCEPT if you also put customers on the same AP.

I am going to ask that you keep your customer delivery separate from your backbone. You will never regret it and in fact will be quite happy later this year.

[Beebe]

You will never regret it and in fact will be quite happy later this year.

Ooooh! maybe that's a subtle hint as to what is coming :) <dances excitedly>

I have one 60 degree 5.8 sector that I use to drive 3 repeaters off of. It works good except for the deminished signal strength because the antenna is not so focused. I'm planning on redoing them with point-to-point links to get the signals up where I need them.

If you've got line of sight and not too much distance this would be no problem.

Thanks,
Roger

[oscarBravo]

We use PtMP backhaul in a few situations, but we've found that where possible it's a better idea to use a dedicated PtP for each link - particularly for busier downstream nodes, or nodes which have other nodes downstream from them again. If you have several busy backbone clients on a single backbone AP, it can get jittery.

YMMV.

[ripv]

It is quite OK to build your backbone with p2mp EXCEPT if you also put customers on the same AP.

I am going to ask that you keep your customer delivery separate from your backbone. You will never regret it and in fact will be quite happy later this year.

Lonnie,

I am setting up a new AP this weekend. It's on the gable of a home office building at someones house. The office building is separate from the house, it even has a separate entrance, so no problem with access :) Anyway part of the deal is I'm giving them free internet. I'm installing a WAR4 to take in the BH and I'll also have 2 sectors to use as AP's. The AP's are pointing directly away from the house so I can't give them their internet from the AP's. As the AP's and the BH will be connected via the local ethernets can I also feed the customer off the ethernet or would this constitute having clients on the backhaul?

[oscarBravo]

That would be fine, and we do it regularly. Contention on a 100Mbit Ethernet interface is a non-issue; contention for the radio interface is the problem.

[ripv]

thanks Paul, its peace of mind to know someone is doing this already without any problems. I was also wondering if the reference Lonnie made to "being quite happy later this year" referred to some sort of PtP optimisation and if so would having a customer on the ether of an AP prevent one using this "optimisation" ? ;)