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All that routing stuff is at a layer higher than I was meaning to
ask about.<br>
<br>
PtMP is just short hand for Point to Multi-Point communication.<br>
<br>
In the two modes of operation you outlined, it seems to me it's
possible for 2 mobile stations to communicate with 1 common fixed
station by simply transmitting packets that bear either a common
2-digit code, or contain the fixed station's callsign. Is the fixed
station capable of sending responses addressed distinctly to each of
the 2 mobile stations? Is the addressing doable on a per-packet
basis, or would the fixed radio need to be re-programmed with a new
destination address (callsign) or something? Can it simply transmit
a frame bearing the common 2-digit code and all stations in earshot
will receive it?<br>
<br>
In terms of multiplexing, how does any station know when it is OK to
transmit? Is there a CSMA scheme or is it just an immediate
transmission when data comes in? Is there something more advanced,
like ARQ?<br>
<br>
In the above scenario, are the 2 mobile stations able to communicate
directly between each other? (assuming all nodes can hear each
other here)<br>
<br>
--Bart<br>
<br>
<br>
<div class="moz-cite-prefix">On 4/27/2014 6:48 PM, Dean Gibson AE7Q
wrote:<br>
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<blockquote cite="mid:535DB372.5040607@ae7q.com" type="cite">
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I had to Google to find out what P2MP was, but in my VERY brief
Google education on the subject, I don't think it applies.<br>
<br>
The radio doesn't multiplex anything.<br>
<br>
The consumer-grade routers I own (Linksys BEFSR41, Netgear
WGT624v2) seem to have no way to turn off NAT. dd-wrt is not
possible with the BEFSR41; it is "work-in-progress" for the
WGT624v2. NAT seems to make routing issues a little more complex
to think through. Both routers have the ability to specify a "DMZ
host", but I think that just turns on universal NAT to that host.
Both routers have the capability of manually adding entries to a
static routing table, but I don't know if that skips over the
NAT. If we have to have NAT, it seems to me that the best way to
set up the router is with the radio connected to the LAN side
(with whatever private IP address we want), and have the WAN side
connected to the 44.x.x.x network. That allows incoming (ie, via
the radio) packets to go wherever they can and responses to come
back; whereas orienting the router the other way (unless we use
the "DMZ host" feature) doesn't. I suppose I could donate one of
my (very) elderly (2005) Dell PowerEdge 1650 1U servers to the
effort, but that seems like a bit of overkill ...<br>
<br>
What I think would be a good idea is to meet and discuss this
face-to-face (pretty much anytime) with diagrams, rather than
shoveling eMails back and forth. Scott, if your schedule permits,
you are more than welcome.<br>
<br>
-- Dean<br>
<br>
ps: Scott, I plan to come to the DEM on Tuesday to start on this,
unless you're not going to be there, or other conditions (like
ongoing slide work) make it a bad idea.<br>
<br>
<div class="moz-cite-prefix">On 2014-04-27 12:06, Bart Kus wrote:<br>
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<div class="moz-cite-prefix">OK, we can slap some extra security
on there. Shouldn't need an extra router for that.<br>
<br>
What about the PtMP story? One of the advantages you
mentioned (Dean) was mobile access. Can it multiplex access
somehow?<br>
<br>
--Bart<br>
<br>
<br>
On 4/27/2014 9:53 AM, Dean Gibson AE7Q wrote:<br>
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Exactly (or the equivalent).<br>
<br>
<div class="moz-cite-prefix">On 2014-04-27 09:34, John Hays
wrote:<br>
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cite="mid:EBCFEB6E-E247-42FB-98E9-FB69315B6DB1@hays.org"
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<div>It should be on a dedicated router on its own segment.
<br>
<br>
Sent from my iPhone</div>
<div><br>
On Apr 27, 2014, at 9:27 AM, Dean Gibson AE7Q <<a
moz-do-not-send="true" href="mailto:hamwan@ae7q.com">hamwan@ae7q.com</a>>
wrote:<br>
<br>
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The only "authentication" the radio has, are the
following:<br>
<ol>
<li>The radio can be set to only receive remote
transmissions that include a two-digit decimal code;
<b>or</b></li>
<li>The radio can be set to only receive remote
transmissions that are addressed to the callsign
programmed into the receiving radio (I would
recommend this setting).<br>
</li>
</ol>
Any other authentication would have to be provided by a
router or firewall.<br>
<br>
<div class="moz-cite-prefix">On 2014-04-26 22:39, Bart
Kus wrote:<br>
</div>
<blockquote cite="mid:535C980B.6090504@bartk.us"
type="cite">Any packets on that LAN are considered
trusted since they passed authentication. What's the
auth story on the 23cm modems? <br>
<br>
--Bart <br>
<br>
On 4/26/2014 10:37 PM, Tom Hayward wrote: <br>
<blockquote type="cite">On Sat, Apr 26, 2014 at 9:26
PM, Dean Gibson AE7Q <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:hamwan@ae7q.com"><hamwan@ae7q.com></a>
wrote: <br>
<blockquote type="cite">At the Snohomish County DEM,
place a router (or bridge) between the ID-1 and
the 44.24.240.x network. <br>
In this scenario, the ID-1 located at my house
would also be connected to a router that acts as
though it were directly connected to the
44.24.240.x (or any other) network at the DEM. <br>
</blockquote>
We have a router at Snohomish County DEM with an
extra port that could be used for this. The subnet
there is 44.24.240.128/28. We have another subnet of
address pairs set aside for router-to-router links.
So as far as networking goes, we could execute your
plan. I can't commend about the feasibility of any
of the other bits. <br>
<br>
Tom </blockquote>
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