Rules of Engagement for Winlink 2000

Revised 1/31/2008

With the advent of the new and enhanced RMS (Radio Message Server) software, and requirements for message handling imposed by MARS, ARES, and VHF/UHF backbone packet networks, there have been a number of significant changes in the way Winlink 2000 (WL2K) accepts and routes messages. Unlike the outgoing PMBOs, the RMS systems provide a direct real-time gateway to the Common Message Server (CMS) system. This does provide a marked improvement on delivery time, the reduction of duplicated messages, a reduction of maintenance headaches for the developers, and an overall improvement in reliability and efficiency. Existing PMBOs will be phased out over the next few months and replaced with RMS Pactor and RMS Packet ports.

Definitions...
The meaning of some commonly used terms needs to be reviewed to understand this document.

• CMS Common Message Server. A redundant geographically dispersed set of mirrored servers that serves as a clearing house for all WL2K messages.
• RMS Radio Message Server. A direct radio port or gateway into the CMS Sites.
• PMBO Participating mailbox. Being phased out.
• Callsign - Legal radio call letters with or without an attached SSID.
• Base Callsign - A callsign without an attached SSID.
• SID - The client protocol ID/Feature string inside square brackets e.g. [Paclink-1.2.34-N03B2FI]
• Address - A token in a To: , Cc: or From: field in a message. An address may any valid Internet e-mail address that begins with SMTP: , a callsign, or a tactical address. Callsigns and tactical addresses may not be elaborated with routing tokens (no packet H-routes).
• Tactical Address - A token with these characteristics;
  1. It must be 3 to 12 characters in length.
  2. It must be unique system wide (the CMBO will enforce this when new tactical addresses are entered).
  3. It must be all alpha characters or alpha characters followed by a dash ( - ) and alphanumeric characters (the total length must be 12 characters or less).
  4. It is not case sensitive.

  Examples of tactical addresses: MLBHOSP, NASHTNEOC-42, ARCORL-4A.

Protocols
RMS sites or CMS telnet ports may be accessed by either of two protocols; B2F or simple ASCII keyboard. These two protocols are documented elsewhere. The B2F protocol that is embedded in Airmail and Paclink MP is by far the preferred method of access that supports efficient message compression as well as file attachments to messages. The ASCII keyboard protocol only supports simple short text messages without attachments.

Addressing Messages
There is a subtle difference between a callsign and an address. A callsign is an address when is appears in a To: , Cc: or From: field in a message, but it is also an identification used to establish radio and telnet links. Only callsigns can be used to establish links, not tactical addresses. Radio and telnet messages will only be accepted addressed to valid radio callsigns, known tactical addresses, or Internet SMTP addresses. Messages from Internet will only be accepted for known addressees. What is a known addressee? It is a radio callsign that has been previously seen via a radio link, telnet link, appears in the header of a message, or was previously manually registered or a tactical address that has been manually registered at the CMS or from a Paclink site.

Tactical addresses are reached from Internet just like ham callsigns: @Winlink.org. (@Winlink.org is stripped off as the message enters the system.) Message addressed to MARS callsigns must have special precedence indicators in the message. This is covered in detail in MARS training documents.

System Message Sizes
Messages entering the system have an absolute size limit of 120,000 bytes compressed. Since messages are not compressed when first composed and since the amount of compression can only be estimated, users will only learn from experience how large a message can be safely entered. Typically .txt, .DOC, .XLS and .PDF files will be reduced substantially, (up to approximately 82 percent), but .GIF, JPG, TIF, or ZIP type already compressed files may only compress a few percent.

The best rule is to keep messages small and avoid the use of cute graphics or HTML formatting. Use text messages whenever possible. If graphics must be sent, ensure that their size is reduced to the smallest practical size. On any given connection to the CMS, messages are sent in the order of their size; the smallest message moving first. The smaller the message the faster it is delivered. If a message exceeds the absolute compressed size limit, a service message will be sent to the sender advising that the message has not been accepted.

Individual User Message Size Limits
Individual users may also restrict the size of messages they will accept. The default limit accepts messages up to 50,000 bytes, compressed.

NOTE: This represents a change from previous practice where a user specified the uncompressed size of any attachment that would be accepted. Now, that number represents the maximum compressed size of the entire message. The limit
cannot be set less than 1000 bytes compressed.

Routing messages...
Under the CMS/RMS system, message routing is greatly simplified. When a message arrives in the system it is mirrored to all of the CMS sites almost immediately. Pending messages are held for 21 days, or until forwarded or delivered. It does not matter which RMS site or channel is used to retrieve a message. It is no longer necessary to check in to a specific RMS site for a message to be immediately available to a new user. (Existing PMBO sites still require check in at least once every 90 days. However, PMBO sites will be entirely phased out over the next few months.)

Dealing with the SSID...
The use of an SSID (i.e. K4CJX-1 or AAR4WU-1) with a callsign is a special condition. The system will recognize a callsign with an SSID only if it is manually registered in advance of use. Otherwise only the base call is used by WL2K and the SSID will be ignored. This gets sticky on some VHF packet networks where the SSIDs get altered as packets are passed from one network node to another. The SSID seen at the RMS TNC may not be the SSID the caller is using. We have a feature to deal with this.

When a station links to WL2K it may add a feature code to the last token in his SID (the ID inside the [ ] ) as follows: Nnn where nn is the originating station's SSID.

A calling station's SID might look like this: [Paclink-1.2.34-N03B2FI] where the calling station s full call is W1ABC-3. WL2K will then treat the connection as a connection from W1ABC-3 even if the packet network changes it to W1ABC-12 or some such call. In other words, it will retain its proper SSID callsign.

A client connecting to WL2K should include N00 in the SID even if no SSID was being used. Otherwise it is always possible that a packet network may add an SSID to the callsign that could be misunderstood by WL2K as a different callsign.

SSID Extensions in Pactor
Callsigns may also include a dash number in Pactor. Strictly speaking these are not SSIDs in the sense they are in packet, but are treated the same as SSIDs by WL2K as described above. When assigning calls for use with Pactor controllers the dash number may need to be limited to the range -1 to -9 since Pactor callsigns are limited to 8 characters (including the dash number). Leading zeros (-01) in the dash number should never be used with a Pactor controller even though it would be acceptable in packet.

Registering Tactical Addresses
Tactical addresses are registered via a dialog in the Paclink MP program. Currently this is only accessed from Paclink installations but can be made accessible to other services as well should the need arise.

Your Winlink Development Team