DualRadios

Category:Sasecurity
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http://www.qorvus.com/phpBB2/viewtopic.php?t=65
If you look at www.fastlineisp.com, you'll see a picture of a 
dual-radio node. In my mesh, I have several of them, each being used 
differently. The one in this picture has one interface for backhaul and 
one interface for local coverage.
That access point is talking to another dual-interface node on a tower. 
The tower node has a sector looking to the southeast and one looking to 
the southwest. It serves up both clients and nodes through those sector 
antennas. That tower node is talking to a dual-radio node back at my 
office. That access point has one interface for local (in-town) 
coverage and a point-to-point interface to the tower.
The access point in that picture is 10 miles from my office and setup 
like this, there is only 6 ms of latency (average) back to the gateway. 
Each interface on a dual-radio node is on separate freq's. This is 
*very* important. You can't put them on the same freq, or even close 
enough that they hear each other - b/c if the interfaces hear each 
other and mesh with each other, you'll get all sorts of craziness.
> Could someone please take a couple of minutes to explain how a dual
> radio node could/would be configured.
> Specifically of interest is knowing if a signal from one radio is 
> passed
> through the mesh box to the other radio. I'm planning to use
> directional/sector antennas. Would I use 2 different channels or the
> same? Here in Spain we are only meant to use 2 channels (11 and 12 I
> think) - aren't they too close together?
> An outline of possible scenarios would be much appreciated (i.e. a
> backhaul channel or using directionals on the same channel and so 
on).
> I've looked at the Wiki and if there are words present I can't find
> them. Some documentation on what can/has been done would be really
> useful.
Dualradios on 2.4 wont work on adjacent channels like that, no matter 
what you do they wil step on eahc oither. They have to be atleat 5-6 
channels apart and even then antenna seperation sb more than 10ft or so. Maybe 
you shoul use 5.8 for backhaiul if thats an option for you. There a good 
writup of dual radios on the qorvus bbs 
http://www.qorvus.com/phpBB2/viewtopic.php?t=65
I tend to dissagree, We have several nodes now that contain dual 
radio's and both are 2.437Ghz (Chan6) I must admit that out of the box they 
will not work but our nodes have been designed to work like this. The only
issue we have had is sometimes where the signal crosses over we have
seen a client (only close clients) having issues electing what sector 
to connect to and occasionally they tend to jump from one to the other 
(the fix for this is to offset the client CPE by a few degrees).
When using dual radios you must take into account the folowing.
1. Ensure both radios are well isolated from each other, We use MiniITX
boards and have a solid copper sheild isolating them. Also this sheild
must be grounded electricaly oitherwise it may try and become an 
antenna
itself.
2. All cable lengths must be tuned (well close to tuned is OK) this 
will reduce the amount of reflected RF.
3. All cables near the Card/Outside connector must be double sheilded
(we also wrap a second sheild around the cabels and earth all sheilds.
4. Make sure the antenna you are using is a sector type and has a good
Back to Front ratio. We have designed and build our own antennas.
5. Antennas must be a specific distance appart and in our case must be
connected to a good earth.
Here is a photo of one of the nodes, actually this is a core node and 
we have something like 8 nodes off this one, with a depth of 4 nodes.
http://www.borg.net.nz/gallery/album12
=== Use a splitter ===
A splitter should work quite well if its set up corectly. Care must be
taken with the cable lengths. Also you will drop the avalible power and
gain when using a splitter. Saying that we have an install that has one
radio that opperates 2 separate sectors and it runs quite well.
One thing to also keep in mind is that 2 X antennas will pick up 2 X 
the amount of noise in the area.
what about using 2 antennas on a radio w/ 2 jacks? I'm using SMC2532W-B
radios and a horizontally polarised long distance omni on the main
antenna jack, but would like to add a vertically polarized short range
omni via a splitter for coverage immediately around the node.
my concern is:
Will the 2 antennas get along? Shouldn't opposing polarisations offset interference? Any chance this could/would work? considerations? Would hooking up an access point to the ethernet jack accomplish the same goals?
Its not that they wont pass traffic but you will loose around50% of 
your data bandwidth due to csma kicking in. You can easily test if your 
bleeding by changine essid to the same on both radios, if they mesh, they see 
each other wirelessly and you will loose the bandwidth. This can make the 
difference betrween 2.5 ad 1.25 mbs sustained.
=== doc somewhere ===
> I tend to dissagree, We have several nodes now that contain dual 
radio's
> and both are 2.437Ghz (Chan6) I must admit that out of the box they 
will
> not work but our nodes have been designed to work like this. The only
> issue we have had is sometimes where the signal crosses over we have
> seen a client (only close clients) having issues electing what sector 
to
> connect to and occasionally they tend to jump from one to the other 
(the
> fix for this is to offset the client CPE by a few degrees).
>
> When using dual radios you must take into account the folowing.
>
> 1. Ensure both radios are well isolated from each other, We use 
MiniITX
> boards and have a solid copper sheild isolating them. Also this 
sheild
> must be grounded electricaly oitherwise it may try and become an 
antenna
> itself.
> 2. All cable lengths must be tuned (well close to tuned is OK) this 
will
> reduce the amount of reflected RF.
> 3. All cables near the Card/Outside connector must be double sheilded
> (we also wrap a second sheild around the cabels and earth all 
sheilds.
> 4. Make sure the antenna you are using is a sector type and has a 
good Back to Front ratio. We have designed and build our own antennas.
> 5. Antennas must be a specific distance appart and in our case must be connected to a good earth.
> Here is a photo of one of the nodes, actually this is a core node and we have something like 8 nodes off this one, with a depth of 4 nodes. http://www.borg.net.nz/gallery/album12
=== ad d ===
Thinking specifically of a dual radio setup where VoIP and sipproxy are
used and using different channels (hmm, that many channels of 
seperation
required huh) and knowing that sipproxy is designed to keep all mesh
VoIP traffic within the mesh.
Won't using different SSID's result in the traffic being routed via the
net as opposed to staying within the mesh or will the box pass data
through to the other radio based on ??????
Its not that they wont pass traffic but you will loose around50% of 
your data bandwidth due to csma kicking in. You can easily test if your
bleeding by changine essid to the same on both radios, if they mesh, they see
each other wirelessly and you will loose the bandwidth. This can make the 
difference betrween 2.5 ad 1.25 mbs sustained.
In qcode the dual radios are bridged at layer 2 and assigned the same 
IP address but seperate essid so that routing / aodv and ny other stuf 
(voip?) that uses the ip adress to route will work through two radiois. This is 
if you use dualradio as gateway ro repeater node and egardles of how essid 
is set. Im not sure how the lw os code ahndles this since it assignes 
seperate IP adresess to each radios