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<div class="moz-cite-prefix">An IGate should not gate messages to RF
addressed to stations that have also been heard on the APRS-IS.
This is precisely why the APRS-IS servers provide packets
originated by stations that have been gated by a given connection
for some period of time after said station was last heard on RF
and gated to the server. So that the IGate can see the TCPIP* in
the path from the server and know that particular station is on
both RF and the -IS and should not have any messages gated to it.</div>
<div class="moz-cite-prefix"><br>
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<div class="moz-cite-prefix">At least, I believe that's what you
were describing as the "loop".</div>
<div class="moz-cite-prefix"><br>
</div>
Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
<br>
<div class="moz-signature"><br>
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<div class="moz-signature">PS. This is rule # 4 from
<a class="moz-txt-link-freetext" href="http://www.aprs-is.net/IGateDetails.aspx">http://www.aprs-is.net/IGateDetails.aspx</a>:</div>
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<div class="moz-signature">
<blockquote type="cite">
<p style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-thickness:
initial; text-decoration-style: initial;
text-decoration-color: initial;">Gate message packets and
associated posits to RF if all of the following are true:</p>
<ol style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-thickness:
initial; text-decoration-style: initial;
text-decoration-color: initial;">
<li>the receiving station has been heard within range within a
predefined time period (range defined as digi hops,
distance, or both).</li>
<li>the sending station has not been heard via RF within a
predefined time period (packets gated from the Internet by
other stations are excluded from this test).</li>
<li>the sending station does not have TCPXX, NOGATE, or RFONLY
in the header.</li>
<li>the receiving station has not been heard via the Internet
within a predefined time period.<br>
A station is said to be heard via the Internet if packets
from the station contain TCPIP* or TCPXX* in the header or
if gated (3rd-party) packets are seen on RF gated by the
station and containing TCPIP or TCPXX in the 3rd-party
header (in other words, the station is seen on RF as being
an IGate).</li>
</ol>
</blockquote>
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<div class="moz-cite-prefix"><br>
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<div class="moz-cite-prefix">On 9/22/2021 5:44 PM, Andrew Pavlin via
aprssig wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1169402712.269925.1632347087498@mail.yahoo.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div class="yahoo-style-wrap" style="font-family:Helvetica Neue,
Helvetica, Arial, sans-serif;font-size:13px;">
<div dir="ltr" data-setdir="false">Greetings.</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">I just discovered an
interesting "loop" caused by I-gating. My Tx I-gate received a
text message from APRS-IS that was originally sent by a
digipeater that I received both by Internet and by long-range
digpeater hop on RF. So, I've heard the station on RF (but not
_local_ RF, because there were one to three digipeaters in the
path by the time I received it on RF). It is one of the
self-addressed text messages that go with telemetry messages
to say how to interpret the telemetry (EQNS, BITS, UNIT,
PARM).</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">So, my Tx I-gate, having
received from the Internet a text message addressed to a
station it has heard over RF, proceeded to transmit the text
message to RF (but without enough digipeat aliases to actually
reach the station).</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">This sounds like a bug in my
I-gate. So is the correct solution:</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">1. never Tx I-gate
self-addressed text messages.</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">2. never Tx I-gate to RF
stations that require more hops than I allow on my Tx I-gate
digipeat path (i.e., for Tx I-gates that can put a WIDE1-1 or
WIDE2-1 on their retransmissions). For the common case of no
digipeat path for Tx I-gating, the RF station would have to be
heard directly (not by digipeater) by the I-gate.</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">So how should I fix my
I-gate?</div>
<div dir="ltr" data-setdir="false"><br>
</div>
<div dir="ltr" data-setdir="false">Andrew, KA2DDO</div>
<div dir="ltr" data-setdir="false">author of YAAC ("Yet Another
APRS Client")<br>
</div>
</div>
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