[aprssig] APRS-IS: frames bypassing server filter

[Mobilinkd LLC]

What would it take to change this behavior so that RX-only iGates with
metered data connections can avoid consuming this unwanted & expensive data?

Kind Regards,

Rob Riggs WX9O
Mobilinkd LLC


On Tue, Jul 14, 2020 at 6:35 PM spam8mybrain via aprssig <
aprssig at lists.tapr.org> wrote:

> The purpose of the minimal data stream is so your Internet-connected
> station can function as a transmit-capable I-gate, not just a receive-only
> I-gate. The minimum packets you receive from the Internet are those
> intended for stations that your I-gate has delivered to the backbone, under
> the assumption that your I-gate is one of the nearest stations to send
> responses back to the RF station. The assumption is, if you can hear them
> on RF, you can send back to them on RF (and the backbone doesn't understand
> the concept of I-gates that can't, so you can't turn off such IS->RF
> traffic).
>
> The backbone sends such packets to all such I-gates that report receiving
> the RF stations, to ensure a redundant path to get to the RF station. After
> all, not all I-gates may be capable of transmitting at the time of packet
> receipt and getting all the way to the RF station (especially if the RF
> station is mobile and has moved since the last RF->IS-forwarded packet from
> it).
>
> Hope this helps explain this design decision of the backbone servers.
>
> Andrew, KA2DDO
>
>
> -------- Original message --------
> From: Wojtek SP9WPN <sp9wpn at gmail.com>
> Date: 7/14/20 18:14 (GMT-05:00)
> To: aprssig at lists.tapr.org
> Subject: Re: [aprssig] APRS-IS: frames bypassing server filter
>
> W dniu 2020-07-14 o 00:12, Lynn W Deffenbaugh (Mr) wrote:
> > You will receive packets generated by any station that you have gated
> > from RF to the APRS-IS for some period of time after you've last gated
> > one of their packets.  Try matching up the stations you're receiving
> > with the packets being subsequently received back from the APRS-IS.
>
> I'm not sure about this. Most of the stations in question are not heard
> directly, but only digipeated to me. This shouldn't count, should it?
>
>
> > This is done for several reasons.  One is to give you the opportunity
> > to gate a "courtesy" posit for the source of any message you may have
> > gated, but it is also so that your IGate can know if a staiton is
> > injecting packets directly to the APRS-IS so you don't gate messages
> > from the -IS to RF for addressed to a station that would have received
> > them directly on the APRS-IS.
>
> Is this true for non-message packets, too? Because I hardly ever see
> APRS messages in the logs, just beacons and telemetry all the time. If
> APRS-IS server sends packets downstream only to stop me from uploading
> the same packets back, it sounds like a weird protocol design...
>
>
> I'd agree with Andrew KA2DDO: it seems there's some "minimal data
> stream" offered to each Igate (and all IS-connected clients are
> considered Igates). It probably serves some good purpose, but is not
> well advertised.
>
>
> Regards,
>
> Wojciech
>
> --
> 73!
> Wojtek SP9WPN
>
>
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