>From: steve@matt.ksu.ksu.edu (Steve Schallehn) >Subject: Explanation of packet radio FAQ >Message-ID: <1991Jul10.130056.25817@maverick.ksu.ksu.edu> >Sender: news@maverick.ksu.ksu.edu (The News Guru) >Nntp-Posting-Host: matt.ksu.ksu.edu >Organization: Kansas State University >Date: Wed, 10 Jul 91 13:00:56 GMT >Lines: 38 I hope most of you have been able to read my packet radio FAQ posting. I intend the FAQ to grow by bounds in the next few versions. I decided to put out version 1.0 *|in it's current status to try to get some ideas from you net.readers. I would like to have as many comments about the FAQ as possible in order to see what else needs to be included. Right now on my to-do list is to add: A separate section with references (RTFM, right? :-) ) A list of magazines with packet radio. Organizations to join. (Newsletters, etc) Coordination Groups and user groups in various areas. (I need help here) Where to get IP addresses for AMPR. More definitions as I find them. More FTP sites/mailing lists. Add info about the AX.25/IP packet wormholes through Internet. Add more networking schemes like TexNet/Flexnet/Pack-ten. (I really need help on this since I have never used them.) Add info on baycomm. Info on modems. Info on fast modems. DX Cluster info. (Anyone have references in ASCII?) Phone line vs. packet modems. Packet BBS systems. Now, what did I forget.... :-) If anyone has any info that would help me out on any of the subjects, I would be happy to have it. Also, if anyone would like to volunteer to do any section, I will gladly include their submission. Thanks. -Steve Schallehn, KB0AGD Kansas State University Frequently Asked Questions for Amateur Packet Radio Part 1 of 3 Version 1.0 9 Jul 1991 This document is for unlimited distribution. Please send corrections and additions to Steve Schallehn (steve@matt.ksu.ksu.edu). This posting will be made on a monthly basis, posted to rec.radio.amateur.packet. u 1.0 Basic Packet Radio Information . . . . . . . . . . . . . . 1 1.1 What is packet radio? . . . . . . . . . . . . . . . . 1 1.2 What is amateur radio?. . . . . . . . . . . . . . . . 2 1.3 Why packet over other digital modes: . . . . . . . . 2 1.4 What elements make up a packet station? . . . . . . . 2 A TNC (Terminal Node Controller) . . . . . . . . . . 2 Computer or Terminal . . . . . . . . . . . . . . . . 3 A radio . . . . . . . . . . . . . . . . . . . . . . 3 1.5 What do you mean we can all use the same channel? . . 3 1.6 What is AX.25 ? . . . . . . . . . . . . . . . . . . . 3 1.7 Definitions: Commonly used terms in Amateur Packet Radio. . . . . . . . . . . . . . . . . . . . . . . . 3 1.0 Basic Packet Radio Information 1.1 What is packet radio? Packet radio is digital communications via amateur radio. Packet radio takes any digital data stream and sends that via radio to another amateur radio station. Packet radio is so named because it sends the data in small burst, or packets. 1.2 What is amateur radio? Amateur Radio is individuals using specified radio frequencies for personal enjoyment, experimentation, and the continuation of the radio art. Amateur radio operators must be licensed by their government. In the United States, the Federal Communications Commission issues amateur radio licenses. Normally, a test on operating practices, radio theory, and in some cases morse code proficiency test is administered. Amateur radio is not to be used for commercial purposes. Also, amateur radio operators are restricted from using profanity and using amateur radio for illegal purposes. For more information on Amateur Radio in general, see the monthly frequently asked questions posting in rec.radio.amateur.misc. 1.3 Why packet over other digital modes: Packet has one great advantage over other digital modes : automatic operation. Packet TNC's are very advanced as far as automatic control go. Just simply connect to the other station, type in your message, and it is sent automatically. Any packet TNC can be used a packet relay station, or a digipeater. This allows for greater range by stringing several stations in a row. On HF, this allows for contacts with stations normally not in propagation range. Packet radio provides error free transmissions because of built in error detection schemes. If a packet is received, it will be correct. Also, on VHF/UHF packet, packet operators are allowed to operate in automatic control mode. This means that you can leave your packet station on constantly. Other users can connect to you at any time they wish to see if you are home. Some TNC's even have Personal BBS's (sometimes called mailboxes) so other amateurs can leave you messages if you are not at home. Another advantage of packet over other modes is the ability for many users to be able to simultaneously use the same frequency simultaneously. 1.4 What elements make up a packet station? A TNC (Terminal Node Controller) A TNC contains a modem to decode the audio signals into digital signals. It also contains a micro-computer handle to convert the digital signals into text that can be sent over a RS-232 port to the computer. The CPU also handles the protocol overhead of the packet station. When you send data, it takes the text, puts error checking on it (CRC) and also puts it in an envelope for sending. When receiving a signal, it takes it out of the envelope, and sends the message to the computer. Computer or Terminal This is the user interface. A computer running a terminal program or just a dumb terminal can be used. For computers, any phone modem communications program can be adapted for packet use or customized packet radio programs are available. A radio For 1200 baud operation (normal user access), a standard voice radio can be used. For UHF or VHF packet, Narrow band FM is used, normally on simplex channels. For HF packet, 300 baud data is used over single side band modulation. 1.5 What do you mean we can all use the same channel? Packet radio uses a protocol called AX.25. AX.25 specifies channel access (ability to transmit on the channel) to be handled by CSCA/CD ?????? (Carrier Sense Collision Avoidance / Collision Detect) If you need to transmit, your TNC monitors the channel to see if someone else is transmitting. If no one else is transmitting, then the radio keys up and the TNC sends it's packet. All the other stations hear the packet and do not transmit until you are done. Unfortunately, 2 stations could accidentally transmit at the same time. This is called a collision. If a collision occurs, neither TNC will receive a reply back from the last packet it sent. Each TNC will wait a random amount of time and then retransmit the packet again. 1.6 What is AX.25 ? AX.25 (Amateur X.25) is the communications protocol used for packet radio. A protocol is a standard for how two computer systems are to communicate with each other, somewhat analogous to using business format when writing a business letter. AX.25 was developed in the 1970's and based of the wired network protocol X.25. Because of the difference in the transport medium (radios vs wires) and because of different addressing schemes, X.25 was modified. AX.25 also included a digipeater field to allow other stations to automatically repeat packets to extend the range of transmitters. One advantage of AX.25 is that every packet sent contains the senders and recipients amateur radio callsign, thus providing identification with every transmission. 1.7 Definitions: Commonly used terms in Amateur Packet Radio HDLC : (High-Level Data Link Control Procedures) A standard for high level link control. (ISO 3309) AX.25 : Amateur X.25 protocol. The basis of most packet systems. See section 1.6. TAPR : Tucson Amateur packet Radio. Was the first group to create a packet radio TNC using AX.25. Soon a TAPR TNC became cloned by many others. TAPR continues development of packet radio equipment. digipeater : A packet radio station used for repeating packets. See section 3.3.1 for more information. digi : Short name for a digipeater NET/ROM : A scheme for packet radio networking. See section 3.3.3 for more information. TCP/IP : Transmission Control Protocol/Internet Protocol. A set of utility programs used over AX.25. See sections 3.2 for more information. KA9Q NOS : (KA9Q Network Operating System) A TCP/IP program originally developed by Phil Karn, KA9Q. Currently there are many different versions available. See section 3.2 for more information. NODE : A network node. Often a network node running NET/ROM. KA-Node : A simple networking scheme developed by Kantronics. See section 3.3.2 for more info. CSCA/CD ???? : Carrier Sense Collision Avoidance / Collision Detect. TNC : Terminal Node Controller. See section 1.4 for more information. AMPR : An abbreviation for Amateur Packet Radio. 44 net : The class A network designator for TCP/IP amateur packet radio. All numerical TCP/IP addresses are in the format of 44.xxx.xxx.xxx. ampr.org : The organization recognized on Internet for amateur packet radio TCP/IP. Frequently Asked Questions for Amateur Packet Radio Part 2 of 3 Version 1.0 9 Jul 1991 This document is for unlimited distribution. Please send corrections and additions to Steve Schallehn (steve@matt.ksu.ksu.edu). This posting will be made on a monthly basis, posted to rec.radio.amateur.packet. 2.0 Computing Network Resources for Amateur Packet radio . . . 1 2.1 What Newsgroups/mailing lists are available?. . . . . 1 2.2 What anonymous FTP sites are available . . . . . . . 2 2.3 Are there any gateways for mail or news . . . . . . . 2 2.0 Computing Network Resources for Amateur Packet radio This section summarizes the resources a vailable on Internet for amateur packet radio operators. 2.1 What Newsgroups/mailing lists are available? This is a list of all groups that regularly discuss amateur packet radio. For newsgroups, subscribe to the group through use of your news reader. For mailing lists, add a '-request' to the end of the list name for subscriptions. For listserv groups, send mail to 'listserv' at the node which contains the list. The first line of the mail should be 'SUBSCRIBE groupname yourname'. Send the command 'help' for more information. rec.radio.amateur.packet (Newsgroup): General discussions involving Packet Radio. rec.radio.amateur.misc (Newsgroup): General amateur radio discussion. Usually does not contain any particular information about Amateur Packet Radio. rec.radio.amateur.policy (Newsgroup): Discussion of regulation policies regarding every aspect of amateur radio. Occasionally deals with polices of packet coordination and legal issues of packet radio. rec.radio.swap (Newsgroup): General for-sale for any radio equipment. Occasionally will have packet equipment for sale. Recommended location for any amateur packet radio for-sale items. info-hams@ucsd.edu (listserv group): A digest redistribution of the rec.radio.amateur.misc Usenet discussion. packet-radio@ucsd.edu (listserv group): A digest redistribution of the rec.radio.amateur.packet Usenet discussion. hs-modem@wb3ffv.ampr.org (mailing list): Discussion of high speed modems and radiosadi available and future plans. Also includes discussion of networking using high speed modems. tcp-group@ucsd.edu (mailing list): Group discussion technical developments of TCP/IP over packet radio and use of the NOS TCP/IP programs. gateways@uhm.ampr.org (mailing list): Discussion of current gateways and future plans for gateways. May deal with sensitive internetworking issues. For all lists at ucsd.edu, archives are kept of the discussions and maybe access via anonymous FTP to ucsd.diedu. Some listserv groups also have archives. Send to the group's listserv 'help' for more information on commands. Digests for the ucsd.edu discussions are available. Send mail to listserv@ucsd.edu with the first line being 'longindex' for more information. 2.2 What anonymous FTP sites are available for getting packet radio information and programs: This is not an inclusive list of FTP sites, but these sites carry a large portion of the programs available. Consult the Archie archivie server for info on particular files. Send mail to archie@cs.mcgill.edu with the line 'help' for more information on archie file searches. ucsd.edu : Primary distribution site of KA9Q's TCP/IP packages. Also, general packet radio information. simtel20.army.mil: very large collection of amateur radio software. wuarchive.wustl.edu: Mirror site of Simtel20 archives. Easier to use then the simtel20 archive. 2.3 Are there any gateways for mail or news between internet and amateur paicket radio? Currently, there is no general use gateways between packet radio or any other computer network. The primary problem with such gateways is required content of amateur packet radio. Most wire based networks do not have any rules on content (such as profanity or business) like amateur radio does. Therefore, all traffic destinated to amateur radio has to be hand filtered. However, there are several experimental wormholes that are being tested through Internet. See the discussion on the gateways discussion group for more information. Frequently Asked Questions for Amateur Packet Radio Part 3 of 3 Version 1.0 9 Jul 1991 This document is for unlimited distribution. Please send corrections and additions to Steve Schallehn (steve@matt.ksu.ksu.edu). This posting will be made on a monthly basis, posted to rec.radio.amateur.packet. 3.0 Networking and special packet protocols. . . . . . . . . . 1 3.1 Are there any other protocols in use other than AX.25? . . . . . . . . . . . . . . . . . . . . . . . 1 3.2 What is TCP/IP? . . . . . . . . . . . . . . . . . . . 1 3.3 Networking Schemes. . . . . . . . . . . . . . . . . . 2 3.3.0 What are some of those other networking schemes?. . . . . . . . . . . . . . . . . . . . 2 3.3.1 Digipeaters. . . . . . . . . . . . . . . . . . 2 3.3.2 KA-Nodes . . . . . . . . . . . . . . . . . . . 2 3.3.3 NET/ROM. . . . . . . . . . . . . . . . . . . . 2 3.3.4 ROSE . . . . . . . . . . . . . . . . . . . . . 3 3.0 Networking and special packet protocols This is a sample of some of the more popular networking schemes available today. By far, there are more customized networking schemes used than listed. Consult your local packet network guru for specific network information. 3.1 Are there any other protocols in use other than AX.25? AX.25 is considered the defacto standard protocol for amateur radio use and is even recognized by many countries as a legal operation mode. However, there are other standards. TCP/IP is used in some areas for amateur radio. Also, some networking protocols use other packet formats than AX.25. 3.2 What is TCP/IP? TCP/IP stands for Transmission Control Protocol/Internet Protocol. This is commonly used over the Internet wired computer network. The TCP/IP suite contains different transmission facilities such as FTP (File Transfer Protocol), SMTP (Simple Mail Transport Protocol), Telnet (Remote terminal protocol), and NNTP (Net News Transfer Protocol) The KA9Q NOS program (also called NET) is the most commonly used version of TCP/IP in packet radio. NOS originally was written for the PC compatible. However, NOS has been ported to many different computers such as the Amiga, Macintosh, Unix System V, and others. Smaller computers like the Commodore 64 and the Timex-Sinclar do not currently have version of NOS available. 3.3 Networking Schemes 3.3.0 What are some of those other networking schemes? During the early days of amateur packet radio, it became apparent that a packet network was needed. To this end, the following packet network schemes were created. 3.3.1 Digipeaters The first networking scheme with packet radio was Digipeaters. Digipeaters would simply look at a packet, and if it's call was in the digipeater field, it would resend the packet. Digipeaters allow the extension of range of a transmitter by retransmitting any packets addressed to the digipeater. This scheme worked well with only a few people on the radio channel. However, as packet became more popular, digipeaters soon were clogging up the airwaves with traffic being repeated over long distances. Also, if a packet got lost by one of the digipeaters, the originator station would have to retransmit the packet again, forcing every digipeater to transmit again and causing more congestion. 3.3.2 KA-Nodes Kantronics improved on the digipeater slightly and created KA- Nodes. As with digipeaters, KA-Nodes simply repeat AX.25 frames. However, a KA-Node acknowledges every transmission each link instead of over the entire route. Therefore, instead of an end- to-end acknowledgement, KA-Nodes allow for more reliable connections because acknowledgments only carried on one link. KA-Nodes therefore are more reliable than digipeaters, but are not a true network. It is similar like having to wire your own telephone network to make a phone call. 3.3.3 NET/ROM NET/ROM was one of the first networking schemes to try to address the problems with digipeaters. A user connects to a NET/ROM as if connecting to any other packet station. From there, he can issue the NET/ROM commands to instruct it to connect to another user locally or connect to another NET/ROM. This connect then connect again means that to a user's TNC, you are connected to a local station only and it's transmissions does not have to be digipeated over the entire network and risk loosing packets. This local connection proved to be more reliable. NET/ROM don't use all of the AX.25 protocol. Instead, they use special AX.25 packet called Unnumbered Information (UI) packets and then put their own special protocol on top of AX.25. This is again used to increase efficiency of it's transmissions. NET/ROM is a commercial firmware (software put on a chip) program that is used as a replacement ROM in TAPR type TNC's. Other programs are available to emulate NET/ROM. Among them are TheNet, G8BPQ node switch, and some versions of NET. NET/ROM nodes, at regular intervals, transmit to other nodes their current list of known nodes. This is good because as new nodes come on-line, they are automatically integrated in the network, but if band conditions such as ducting occur, often unreachable nodes are entered into node lists. This causes the NET/ROM routing software to choose routes to distant nodes that are impossible. This problem requires users to develop a route to a distant node manually defining each hop instead of using the automatic routing feature. 3.3.4 ROSE Rose is another networking protocol derived from X.25. Rose nodes have a static list of the nodes it can reach. For a user to use a ROSE switch, he issues a connect with the destination station and in the digipeater field places the call of the local rose switch and the distant rose switch the destination station can hear. Other then that, the network is completely transparent to the user. The static routing tables ROSE uses ensures that packet routing does not use unreliable links such as NET/ROM suffers from. However, ROSE suffers from it's inability to change it's routing table as new nodes come on line. The operator must manually change every routing table, thus ROSE networks require greater mainten