Pack Networks And 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. 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. Often, special packet radio protocols are encapsulated within AX.25 packet frames. This is done to insure compliance with regulations requiring packet radio transmissions to be in the form of AX.25. However, details of AX.25 encapsulation rules vary from country to country. 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, and others. Smaller computers like the Commodore 64 and the Timex- Sinclar do not currently have version of NOS available. Networking Schemes 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 where created. 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. 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. 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, MSYS, 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. 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 maintenance times. BBS message transfer Many of the BBS programs used in packet radio allow for mail and bulletins to be transferred over the packet radio network. The BBS's use a special forwarding protocol developed originally by Hank Oredsen, W0RLI. Besides full service BBS's, many TNC makers have developed Personal BBS software to allow full service BBS to forward mail directly to the amateurs TNC. This allows operators to receive packet mail at night and avoid tying up the network during busy hours.