I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
Thanks,
Michael
N6MEF
On Thu, Mar 2, 2017 at 3:16 AM, Michael Fox - N6MEF n6mef@mefox.org wrote:
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
Seems like this might be what you're looking for
[Internet Protocol Encapsulation of AX.25 Frames](https://tools.ietf.org/html/rfc1226)
Nope. That's AXIP. The question was about AXUDP.
Michael N6MEF
-----Original Message-----
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
Seems like this might be what you're looking for
[Internet Protocol Encapsulation of AX.25 Frames](https://tools.ietf.org/html/rfc1226)
Well if one first dropped the 'AX' portion of your question and re-read it more as "What is UDP ?" one might get this.
A short answer is "UDP (User Datagram Protocol) is an alternative communications protocol to Transmission Control Protocol (TCP) used primarily for establishing low-latency and loss tolerating connections between applications on the Internet. ... Both protocols send short packets of data, called datagrams. "
Then a novice to both amateur radio and packet might ask about the 'AX' portion.
While I can't be certain, I believe the AX prefix to UDP might have been added to simply specify "in amateur radio uses" most likely borrowed from the 'AX.25' protocol name.
And while you've been in ham and packet radio for a good many years, Michael, I'll add a definition of the AX.25 protocol here for those that are new(ish).
"AX.25 (Amateur X.25) is a data link layer protocol derived from the X.25 protocol suite and designed for use by amateur radio operators. It is used extensively on amateur packet radio networks. AX.25 v2.0 and later occupies the data link layer, the second layer of the OSI model. "
I'm not entirely sure if that answers your question, but I hope so.
Bill / KG6BAJ
At 07:20 AM 3/2/2017, you wrote:
(Please trim inclusions from previous messages) _______________________________________________ Nope. That's AXIP. The question was about AXUDP.
Michael N6MEF
On Thu, Mar 02, 2017 at 07:20:21AM -0800, Michael Fox - N6MEF wrote:
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
AXUDP is the transmission of AX.25 frames within UDP over the internet. Similar to AXIP, it uses UDP instead of raw IP.
To the best of my knowledge, there is no official definition of AXUDP.
There was some discussion of AXUDP and the XNET protocol in the F6FBB forums but no formal definition that I know of. - Brian
On Thu, 2 Mar 2017 07:55:08 -0800 Brian Kantor wrote:
On Thu, Mar 02, 2017 at 07:20:21AM -0800, Michael Fox - N6MEF wrote:
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
AXUDP is the transmission of AX.25 frames within UDP over the internet. Similar to AXIP, it uses UDP instead of raw IP.
To the best of my knowledge, there is no official definition of AXUDP.
Brian,
(I'm new here, be gentle) ;-)
The list of UDP ports at Wikipedia(1) doesn't show port 93 or 10093, so I suggest we correct Wikipedia's list, since port 93 is shown as assigned to "Device Control Protocol" by the IANA(3).
I don't know if we can apply for something like port 114, so please tell me if a "System" port number would be appropriate for AX.25-over-UDP, and if a new IP protocol number is needed. TIA.
Bill, W4EWH
1. https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers 2. https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers 3. http://www.iana.org/assignments/service-names-port-numbers/service-names-por...
The list of UDP ports at Wikipedia(1) doesn't show port 93 or 10093, so I suggest we correct Wikipedia's list, since port 93 is shown as assigned to "Device Control Protocol" by the IANA(3).
Yes, our usage of port 93/UDP for AXUDP is completely unrecognized by IANA. There is no official document describing AXUDP so there is no way for us to claim a port - although there's no prohibition on using any port number we want, since port numbers are not absolutes. Still, it's not wise to double-up on port numbers.
In general, high numbered ports like 10093 are up for grabs, so we can continue to use it unless someone bigger comes along and claims it. If someone writes up a protocol description of AXUDP, we can publish that document and then use it as justification for claiming 10093. That would give us a reference for inclusion of port 10093 in Wikipedia's list.
I don't know how many implementations of AXUDP are hard-coded to use port 93, nor how many host pairs are using it that would have to change if we made 10093 'official' in some way. Something might break.
I don't know if we can apply for something like port 114, so please tell me if a "System" port number would be appropriate for AX.25-over-UDP, and if a new IP protocol number is needed. TIA.
I don't think we need a well-known 'system' port number (ie, 1023 and lower) because all AXUDP connections are by agreement. All we need is a port that's unlikely to be used for anything else.
No, a new IP protocol number isn't needed, since it's using UDP (which is IP protocol 17), not raw IP, for transport. - Brian
Brian,
Since you state there is no official definition, but give a rather eloquent definition of it, is it possible to include your definition somewhere on the WIKI ?
Bill KG6BAJ
At 07:55 AM 3/2/2017, you wrote:
(Please trim inclusions from previous messages) _______________________________________________ On Thu, Mar 02, 2017 at 07:20:21AM -0800, Michael Fox - N6MEF wrote:
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
AXUDP is the transmission of AX.25 frames within UDP over the internet. Similar to AXIP, it uses UDP instead of raw IP.
To the best of my knowledge, there is no official definition of AXUDP.
There was some discussion of AXUDP and the XNET protocol in the F6FBB forums but no formal definition that I know of. - Brian _________________________________________ 44Net mailing list 44Net@hamradio.ucsd.edu http://hamradio.ucsd.edu/mailman/listinfo/44net
Any description I gave would be necessarily incomplete, as I don't know frame sizes, port numbers, etc. Someone familiar with the implementation code could probably write the description fairly easily.
I was rather hoping that the people maintaining the AXUDP software would speak up. I think that JNOS or one of those programs implements it and hope that the author of the protocol was still with us. Some of the early packet pioneers have since died.
On Thu, Mar 02, 2017 at 08:01:57AM -0800, William Lewis wrote:
Since you state there is no official definition, but give a rather eloquent definition of it, is it possible to include your definition somewhere on the WIKI ?
I'm not aware of any formal spec, but Michael N6MEF's suggestion pretty much covers it. The only difference I've come across between implementations is that some require a specific source port as well as the defined destination port.
There seem to be two commonly used ports (93 and 10093).though others are also used. Using low numbered ports can be a problem with some operating systems (requiring root/admin rights) so I prefer 10093
73, John G8BPQ
-----Original Message----- From: 44Net [mailto:44net-bounces+john.wiseman=cantab.net@hamradio.ucsd.edu] On Behalf Of Brian Kantor Sent: 02 March 2017 16:18 To: AMPRNet working group Subject: Re: [44net] AXUDP spec
(Please trim inclusions from previous messages) _______________________________________________ Any description I gave would be necessarily incomplete, as I don't know frame sizes, port numbers, etc. Someone familiar with the implementation code could probably write the description fairly easily.
I was rather hoping that the people maintaining the AXUDP software would speak up. I think that JNOS or one of those programs implements it and hope that the author of the protocol was still with us. Some of the early packet pioneers have since died.
On Thu, Mar 02, 2017 at 08:01:57AM -0800, William Lewis wrote:
Since you state there is no official definition, but give a rather
eloquent
definition of it, is it possible to include your definition somewhere on
the
WIKI ?
_________________________________________ 44Net mailing list 44Net@hamradio.ucsd.edu http://hamradio.ucsd.edu/mailman/listinfo/44net
I'm not aware of any formal spec, but Michael N6MEF's suggestion pretty much covers it. The only difference I've come across between implementations is that some require a specific source port as well as the defined destination port.
FYI John, in case you aren't aware:
JNOS used to require that the source port for incoming packets be specified when setting up the AXUDP interface in JNOS. Of course, that's very unusual for IP protocols and also easily broken by firewalls. In JNOS 2.0j.5 (June 2014), Maiko added the option to specify "-1" for the incoming source port, meaning "don't care". This is what I use with all AXUDP connections, including to BPQ systems. http://www.langelaar.net/projects/jnos2/documents/changes.txt
There seem to be two commonly used ports (93 and 10093).though others are also used. Using low numbered ports can be a problem with some operating systems (requiring root/admin rights) so I prefer 10093
Agreed.
Michael N6MEF
I'm looking for the specific definition of AXUDP. Is there an official protocol specification for AXUDP somewhere?
There was some discussion of AXUDP and the XNET protocol in the F6FBB forums but no formal definition that I know of.
- Brian
Thanks, Brian.
Hmmm. Several BBSs implement it. One would think that there would be some declarative document that all implementers agreed to, even if it is as simple as the AXIP RFC. But I'm unable to find anything either.
If such a document truly doesn't exist, then perhaps we should document it somewhere. It should be as simple as a cut and paste the language of RFC 1226, substituting "UDP" for "IP" where appropriate, and substituting "default port number of 93" instead of "protocol number of 93".
To wit:
User Datagram Protocol Encapsulation of AX.25 Frames
Status of this Memo
This memo describes a method for the encapsulation of AX.25 (the Amateur Packet-Radio Link-Layer Protocol) frames within UDP packets. This technique is an Experimental Protocol for the Internet community. Discussion and suggestions for improvement are requested.
The AX.25 Amateur Packet-Radio Link-Layer Protocol
The AX.25 Amateur Packet-Radio Link-Layer Protocol is described in the publication by that name [1], incorporated here by reference.
Each AX.25 packet ("frame") is encapsulated in one UDP datagram. Normally no AX.25 frame will exceed 330 octets, so fragmentation at the IP layer should not be necessary. However, experiments with larger AX.25 frame sizes may require the use of standard IP fragmentation and reassembly procedures.
When an AX.25 frame is encapsulated within a UDP packet, HDLC framing elements (flags and zero-stuffing) are omitted, as the UDP datagram adequately delimits the beginning and end of each AX.25 frame. The 16-bit CRC-CCITT frame check sequence (normally generated by the HDLC transmission hardware) is included. In all other respects, AX.25 frames are encapsulated unaltered.
The default port number for AXUDP is UDP port 93.
Reference
[1] AX.25 Amateur Packet-Radio Link-Layer Protocol Version 2.0 October 1984. Available from the American Radio Relay League, Newington CT USA 06111, and other sources.
Security Considerations
Security issues are not discussed in this memo.
Michael N6MEF
On Thu, Mar 02, 2017 at 08:14:28AM -0800, Michael Fox - N6MEF wrote:
If such a document truly doesn't exist, then perhaps we should document it somewhere. It should be as simple as a cut and paste the language of RFC 1226, substituting "UDP" for "IP" where appropriate, and substituting "default port number of 93" instead of "protocol number of 93".
Unfortunately, there are problems with AXIP and AXUDP ever since the revisions of AX.25 were published - the AX.25 frames may get too big to encapsulate in unfragmented IP and UDP frames. Any new document would have to discuss the fragmentation issues, and I'll bet they're not defined. (As far as I know, the same issue applies to ROSE, KISS, and Net/Rom encapsulation too.)
Do any of the various implementations of AX.25 encompass v2.0 et seq as published by TAPR? Ie, is anyone actually implementing jumbo frames, expanded frame sequence numbers, etc? Or should we just treat it as a bad idea that should be buried and go on with the old protocol? - Brian
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Bill Horne W4EWH -
Brian Kantor -
John Wiseman -
Kyle Jones, KF5JWC -
Michael Fox - N6MEF -
William Lewis