[Xastir] Digipeating

[Curt, WE7U]

On Wed, 1 Sep 2004, hasan schiers wrote:

> From: "Tapio Sokura" <oh2kku at iki.fi>
> To: <xastir at lists.xastir.org>
> Sent: Tuesday, August 31, 2004 10:23 PM
> Subject: Re: [Xastir] Digipeating
>
> "If you use the Linux kernel AX.25 stack, you can run as many AX.25
> programs as you like side by side and there will be no problems with
> having just one TNC. When using the kernel AX.25 stack the kernel does
> all the talking to the TNC. The programs talk to the kernel when they
> want access to AX.25 devices instead of directly going for the serial port."
>
>    Tapio
>
> If this is accurate, I'm set, i.e., if both programs talk to the kernal and
> the kernal manages the ports, then there is no port contention. Someone
> else's reply said just the opposite, however.

Keep serial port access and AX.25 kernel port access separate.  Yes,
you'd get contention if you were trying to have two programs talk to
the same serial port.  By using the AX.25 kernel ports instead, you
avoid that, at the expense of more complicated setup.


> First of all, several replies seem to think I'm criticizing xastir...that is
> NOT the case. I'm trying to UNDERSTAND, how to implement what is NECESSARY
> for my function and role in the local aprs network. I'm an important digi
> and igate. I need to be able to do two things with the same RF hardware and
> TNCs:

Feel free to criticize it anyway (even though that's not what you're
doing).  We're fairly open here.  Also make sure to get familiar
with the bug reporting and feature request lists on Xastir's
SourceForge pages.  You'll be making use of them if you run Xastir
for any length of time.  Forgetting to put something on the bug list
means it won't get fixed.  Forgetting to put something on the RFE
list means the developers won't even consider adding the feature,
unless they think of it themselves independently and it's personally
important for them to add it.


> 1. Be an effective aprs client with full igate performance. Xastir will
> clearly do this.

Yes.  There may be some igate functionality that you are used to
from UI-View32 that isn't in Xastir however.


> 2. Be an effective SMART aprs digi

Nope, and we won't be adding that.  Performed by other apps much
better than we could ever hope to do/maintain.


> Simply put, is there or is there not a way to do this? If I understand Tapio
> correctly, this can be done, others have said it will require a separate
> comm port and separate tnc's and separate radios for Xastir and
> Digi-ned....precisely what I'm trying to avoid.

It can be done.  Take my word as one of the busier Xastir
developers.  I've done it.  I've also run Xastir talking to multiple
internet servers, talking to a remote AGWPE port, talking to local
serial port TNC's and GPS'es, talking to remote GPS's (using the
gpsd daemon), and talking to AX.25 kernel mode TNC's.  I've done
most of these all at the same time as well (Xastir can define up to
15 interfaces).  About the only thing I haven't personally done is
use a linux soundcard modem configuration, but at least one of the
other Xastir developers has done this, and we have users which have
this configuration.


> For it to work on linux, both client programs need to talk to a "port
> manager" of some sort, whether it is the kernal, agwpe on another machine,
> something...in ui-view32 this is done internally (the digi) and it is done
> VERY well. Since Xastir doesn't do it at all, then a 2nd client is required.
> This would appear to be digi-ned, if and only if, Tapio's characterization
> is correct.

Windows vs. Unix methodology.  Get used to it.


> I'm really not trying to run this in to the ground or be difficult. I really
> want this to work, and it has to work "conceptually" the way I describe,
> within the hardware limits I have stated. The question is how is this done
> with Xastir and "whatever digi client" being suggested?

You might be interested in subscribing to the "linux-hams" mailing
list, as that's mostly where the AX.25 kernel interfaces experts
hang out.  I've done it numerous times over the last 10 years or so,
but that mailing list and the AX.25 HOWTO document are very helpful.
Just be aware that the HOWTO document is consistently out-of-date,
so you may need personal help to set things up.  Many people do.


> Again, thanks for your patience, in trying to explain to someone who is just
> beginning to scratch the surface of this exciting piece of software and a
> totally different OS.

At least you're asking questions...  That's the first step to being
a Unix power user.

--
Curt, WE7U			         http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"