RFC 1226

RFC 1226

[Nick Schmalenberger]

list:
A few weeks ago, I sent this message to Brian Kantor, the author of RFC
1226. I haven't gotten any response, so maybe you can answer my
questions. Also, in the AX.25-HOWTO, it talks about these network layer
protocols like NETROM and ROSE, and I can't understand what they are for.
Why not just use IP? In the database of Linux Ham radio applications, it
has a fileserver for AX.25. Why not just use the existing facilities in
Linux? What is so special about radio that all this stuff needs to be
reinvented incompatibly?
On Thu, 12 Feb 2004 20:46:47 -0800, "Nick Schmalenberger"
<nschmalenberger@fastmail.fm> said:
> Brian Kantor:
> I read your RFC 1226, and I wonder why would an AX.25 frame be
> encapsulated in an IP datagram? Is this some form of tunneling? Why not
> just have AX.25 carry IP, and AX.25 would be a link-layer protocol just
> like Ethernet, PPP, or 802.11? Also, do you know where I can find the
> specification for APRS? I've looked at TAPR, and I couldn't find it. Why
> doesn't APRS use IP and UDP? Thanks.
> Nick, KG6PIP
Thanks,
Nick, KG6PIP

-- 
http://www.fastmail.fm - Choose from over 50 domains or use your own

Re: RFC 1226

[Mike Murphree]

On Feb 29, 2004, at 7:21 PM, Nick Schmalenberger wrote:

> list:
> A few weeks ago, I sent this message to Brian Kantor, the author of RFC
> 1226. I haven't gotten any response, so maybe you can answer my
> questions. Also, in the AX.25-HOWTO, it talks about these network layer
> protocols like NETROM and ROSE, and I can't understand what they are 
> for.
> Why not just use IP? In the database of Linux Ham radio applications, 
> it
> has a fileserver for AX.25. Why not just use the existing facilities in
> Linux? What is so special about radio that all this stuff needs to be
> reinvented incompatibly?

Ahhhh, you're too funny....   "all this stuff" as you put it, occurred
before Phil Karn, KA9Q, ever produced "Net" which was the first 
recognized
debut of TCP/IP over radio.  "All this stuff" also occurred before Linux
was created too.  There are a *lot* of things that are different about
radio than required by a wired network.  Linux's support of NETROM and 
ROSE
(and half-dozen others) is there to remain compatible with existing 
radio
network nodes that were totally incapable of running something as 
massive
as Linux.  But to answer your question, yes, it is possible to run just 
IP,
but you need a decent computer at each node (excluding TheNetX1J) to 
run it
with any success...

> On Thu, 12 Feb 2004 20:46:47 -0800, "Nick Schmalenberger"
> <nschmalenberger@fastmail.fm> said:
>> Brian Kantor:
>> I read your RFC 1226, and I wonder why would an AX.25 frame be
>> encapsulated in an IP datagram? Is this some form of tunneling? Why 
>> not
>> just have AX.25 carry IP, and AX.25 would be a link-layer protocol 
>> just
>> like Ethernet, PPP, or 802.11? Also, do you know where I can find the
>> specification for APRS? I've looked at TAPR, and I couldn't find it.

You can't route AX.25 on the internet directly, it's incompatible, hence
a tunnel is required...

>>  Why
>> doesn't APRS use IP and UDP? Thanks.
>>

APRS was designed for packet radio, and not the internet...

73
Mike W4LNA

Re: RFC 1226

[Hamish Moffatt]

On Sun, Feb 29, 2004 at 10:30:40PM -0600, Mike Murphree wrote:
> On Feb 29, 2004, at 7:21 PM, Nick Schmalenberger wrote:
> >> Why
> >>doesn't APRS use IP and UDP? Thanks.
> 
> APRS was designed for packet radio, and not the internet...

Indeed. APRS could send UDP packets over broadcast IP, but what would
be the benefit? You have several extra layers of protocol (at least 30
bytes of headers) for no benefit.

Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>

Re: RFC 1226

[Tomi Manninen]

On Mon, 2004-03-01 at 03:21, Nick Schmalenberger wrote:

> A few weeks ago, I sent this message to Brian Kantor, the author of RFC
> 1226. I haven't gotten any response, so maybe you can answer my
> questions. Also, in the AX.25-HOWTO, it talks about these network layer
> protocols like NETROM and ROSE, and I can't understand what they are for.
> Why not just use IP? In the database of Linux Ham radio applications, it
> has a fileserver for AX.25. Why not just use the existing facilities in
> Linux? What is so special about radio that all this stuff needs to be
> reinvented incompatibly?

Radio does indeed pose problems that are not present in land line
networks. Mainly the high packet loss (due channel access, collision
detection, interference and propagation being much more challenging)
is a problem.

Ham radio poses even more problems. It's next to impossible to build
a properly co-ordinated network so any L3 protocol should have an 
automatic and quickly converging routing protocol on top of it.

When AX.25 was devised roughly 20 years ago they didn't specify
any L3 protocol. Possibly because of the limits posed by the
available (to the average ham) processing power and memory.
This resulted in the development of many rivalling upper level
schemes which is partly a good thing, partly a bad thing.

Anyway I think TCP/IP was a late entrant to the scene, required
relatively big amount of computing power, had a high overhead
and didn't have a working routing protocol. And then there 
probably were social reasons why IP over AX.25 never made a
big breakthrough.

And one has to remember, 15 to 20 years ago TCP/IP didn't
have nearly the status of de-facto standard of networking like 
it has now. The Internet of today didn't really exist...

> > I read your RFC 1226, and I wonder why would an AX.25 frame be
> > encapsulated in an IP datagram? 

Because of the above, ie. the fact that we still largely use AX.25
with our own upper layer protocols and even without any L3 protocol,
there still is a need for encapsulating AX.25 in IP frames for
tunneling over the Internet. Hence RFC1226.

> > Why
> > doesn't APRS use IP and UDP? Thanks.

The APRS "protocol" is basically a collection of standard text 
messages that are sent out as broadcasts and propagated in the
"network" in a simple flood like fashion. I don't see much
benefit in adding the overhead of IP/UDP...


(I hope the above makes sense to those that have been around 
longer than me. I have only about 12-13 years of experience 
in packet radio...)

-- 
Tomi Manninen / OH2BNS / KP20ME04

Re: RFC 1226

[Leo Bistmans]

On Sun, 29 Feb 2004 17:21:32 -0800
"Nick Schmalenberger" <nschmalenberger@fastmail.fm> wrote:

> > Also, do you know where I can find the
> > specification for APRS? I've looked at TAPR, and I couldn't find it. 

ftp://ftp.tapr.org/aprssig/aprsspec/spec/aprs101/APRS101.pdf

 Not that is is very readable %)