[aprssig] of interest to IGate client authors?

Kenneth Finnegan kennethfinnegan2007 at gmail.com
Sat Nov 26 01:48:31 EST 2016

On Fri, Nov 25, 2016 at 9:53 PM, Jim Alles <kb3tbx at gmail.com> wrote:

> ​​This test, from http://www.aprs-is.net/IGateDetails.aspx:
> "the receiving station has not been heard via the Internet within a
> predefined time period."
> seems to have lost it's context.
> [...]
> It appears to me that if the former rule above is applied literally and
> too broadly, then only the first IGate hearing the destination station has
> a chance of transmitting.

As the sentence ironically right after the one you quoted says:

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).

So no, there is no race condition. If you're seeing packets from a station
with TCPIP* in the header, they're connected to the APRS-IS directly and
don't need your RF-gate services. If you're seeing packets via the APRS-IS
from an RF-only station which were I-gated by other stations, it would not
have TCPIP* in the header.

> Another operational concern is interpretation of whether it just the
> callsign or the CALL+SSID that is used in the test at the IGate client,
> since we now have mobile devices that are only heard on the Internet, while
> the same operator may be running a transceiver with a different SSID. They
> should both get each others message, regardless that the Internet connected
> device is not RF.

Where did did you get this from? Every BaseCallsign-SSID station callsign
is a unique identifier and should be handled separately. I think some
software will notify you if they happen to see messages for other SSIDs of
the same base callsign, but I find the feature annoying

> If a message is destined for a Internet-only client, and an RF station
> with the same callsign is heard elsewhere, the RF remote should also get a
> copy of the message, due to the common callsign.

No it shouldn't. Why should every station operating with my base callsign
get a copy of every message destined for any of my stations? If I'm
operating 15 digipeaters across the state and I send a command to one of
them via APRS messaging, why should the other 14 get a copy of the message
not meant for them?

The local RF-gate wouldn't know anything about the actual destination
anyways, since it wouldn't have necessarily seen any packets from my other
SSIDs, so there's no way to identify a different SSID station as "a
Internet-only client". You're now talking about a change to not only
RF-gates but the behavior of the APRS-IS 14580 port as well.

Kenneth Finnegan, W6KWF
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