Many Isode applications are optimized for use over Radio, Satellite and other multicast and potentially low quality/performance links. Although this functionality may have general application, Military organizations are the primary target of these applications, and a number of protocols specified for military use are key to Isode's product set.

This solutions page gives an overview of the products and management tools that Isode provides for Radio and Satellite networks, giving a communication network oriented view of the Isode product set.

What Isode Provides

Isode provides server software applications that are optimized for radio and satellite networks. Isode's core approach is to provide server-to-server communication, as this enables maximum efficiency to be obtained from the underlying networks, and isolates clients from those underlying networks. This allows use of standard clients, as specialized functionality is provided by the servers. Clients can connect directly to the Isode servers, or indirectly via other servers.

Isode provides the following applications optimized for Satellite and Radio:

Isode's application suite is unique in that:

  • It provides support for a broad set of applications.
  • It is independent of any radio (or satellite) vendor, providing integration with standard protocols.
  • It offers applications over both IP and STANAG 5066 for supporting non-IP radios.

Why use Special Protocols?

There are a number of reasons why Isode servers and the special protocols they use are preferable to running standard applications over Satellite and Radio:

  • Low speed. Modern applications are generally optimized for use over medium and high speed networks. The overheads are not acceptable for slow networks. For this reason, NATO mandates use of STANAG 4406 Annex E for communication links slower than 20 kilobits per second.
  • Multicast. Standard application protocols are point to point, and cannot take advantage of the multicast nature or radio and satellite networks.
  • EMCON (Emission Control or Radio Silence). It is sometimes desirable to communicate with units that do not transmit. Standard application protocols cannot support this.
  • Network characteristics. As well as being slow, radio networks exhibit characteristics which are awkward for applications, including high latency, long turnaround time, data loss, and variable bandwidth. This is a particular problem for HF Radio, which means that special protocols (and in particular STANAG 5066) are essential.

Application Integration with the Network

Isode provides applications (servers), and it is important to understand the interface between the application and the network. Isode offers two choices:

  1. IP. Internet Protocol is widely used and is an almost universal interface between application and network.
  2. STANAG 5066 is a data link protocol designed for use over HF Radio, as illustrated above. It can support IP as a STANAG 5066 application. When this paper considers STANAG 5066, it is looking at direct Isode server application use of the STANAG 5066 protocols.

The choice of which integration protocol to be used will depend on the network being used. Isode makes the following recommendations:

  • Satellite. Use IP.
  • SHF and faster Radio. Use IP.
  • HF Radio. Use STANAG 5066. Use of IP will give very poor performance, and should not be used.
  • VHF Radio. Use STANAG 5066. It will give significantly better performance than IP, and for 9600 baud channels this is important.
  • UHF Radio. It is unclear which is best. STANAG 5066 will give better performance if it is available.

Isode is planning to introduce Icon 5066, its own STANAG 5066 server product, described in the whitepaper [Icon 5066 & Isode’s Strategy for Modem Independent Application Deployment over HF Radio].

Server to Server Communications

Isode's core approach to HF and Satellite is to use server to server communication only. There are two basic reasons for doing this and for not using any client/server protocols:

  1. It enables use of standard client products, without any need to adapt to constrained networks, with special protocols or configuration.
  2. It isolates the client from the network, and so isolates the user from network related performance problems.

Military Formal Messaging



Military Formal Messaging (STANAG 4406) defines protocols to work over Satellite and Radio, and Isode's implementation follows these standards for 'constrained networks'. These standards allow operation on mobile units and also define gateway procedures to 'high speed' environments. A configuration as shown above is typical.

These protocols are implemented by our M-Switch MTA. Further information can be found on our page on STANAG 4406 Military Messaging.

ACP127 Messaging and BRASS

Isode supports the older ACP127 family of military messaging protocols. These can be operated over HF Radio using STANAG 5066 and also operating directly over HF modems. This is often used for Naval communication and in particular for BRASS (Broadcast and Ship to Shore). Futher information can be found in the whitepaper [Isode's Solution for BRASS (Broadcast and Ship to Shore)].

Internet Messaging

Internet email is an important application. Isode provides this by use of the same ACP 142 infrastructure used by STANAG 4406. This provides an integrated solution for support of Internet Messaging. These protocols are described in more detail in the whitepaper [Messaging Protocols for HF Radio]. Military messaging over SMTP is supported using RFC 6477 and related extensions.

These protocols are implemented by M-Switch and the capabilities are described in more detail in the page on M-Switch for Constrained Networks and HF Radio.

Directory Replication



Client/Server directory access over a slow network would give very poor user performance, so the best approach is to replicate directory data. Rather than define a special protocol, it is noted that email (both Internet and STANAG 4406) provide a reliable multicast infrastructure with data compression. This is a natural building block for directory replication, which Isode provides in its Sodium Sync product. This generates LDIF (LDAP Data Interchange Format) files to efficiently provide incremental changes to one or more peer directory servers. This is described in more detail in the Isode whitepaper [Directory Replication by Email and over 'Air Gap'].

File Transfer

Isode provides 'File Transfer by Email' as an infrastructure component to support directory replication in M-Switch. This is a general purpose capability that could be used to support end user file transfer or other applications needed a reliable data exchange infrastructure. For example, it could be used to support database replication. This application is described in more detail in the Isode whitepaper [File Transfer by Email].

XMPP for IM and Presence

Instant Messaging and Presence is of increasing importance for Military and Government deployments. Operating XMPP over slow Radio and Satellite networks has a number of difficulties to solve that are specific to this application and described in the whitepaper [Operating XMPP over Radio and Satellite Networks]. Our Military XMPP page provides more information on our support of this.

Supporting Applications

STANAG 5066 Performance Testing

Isode provides support for some additional capabilities over HF Radio, using its STANAG 5066 Console product shown above. This includes:

  • Operator Chat - a simple protocol for basic HF Operator Communication, defined in STANAG 5066.
  • Service Discovery, to facilitate setting up a STANAG 5066 application network.
  • Performance testing, to help measure and test infrastructure.

More details are given on the STANAG 5066 Console product page.

Further Information

For further information see our solutions pages on Military Messaging, Military Directory and Military XMPP. We regularly publish whitepapers on subjects relating to this area which can be found here. These include:

  • Federated Mutli-User Chat: Efficient and Resiliant Operation over Slow and Unreliable Networks
    XMPP (the Internet Standard eXtensible Messaging and Presence Protocol) Multi-User Chat (MUC) is normally provided by a single server, with clients accessing a MUC Room via their local XMPP servers. This standard approach gives performance and resilience problems when operating over constrained networks. This paper looks at how federating the MUC service can address these problems. Isode's approach to Federated MUC as implemented in the M-Link XMPP server is described in the context of evolving XMPP standards, and benefits of Federated MUC for purposes other than Constrained Networks are considered.
  • Performance Measurements of Applications using IP over HF Radio
    This paper sets out the results of measurements made when running applications and layer protocols to support applications over IP via HF Radio using STANAG 5066. The goal of this work was to get a quantitative measure of the performance impact of using applications running over IP over HF Radio in comparison with applications running directly over specialized HF Radio protocols. This paper concludes that the performance impact of using IP is massive, with small message latency increase from at typical value of 6-20 seconds using applications optimized for HF to a smallest measured value of 89 seconds when using IP.
  • Isode's Solution for BRASS (Broadcast and Ship to Shore)
    BRASS (Broadcast and Ship to Shore) is an approach used by Navies, particularly in NATO countries, to communicate between Ships and Shore using HF Radio. This whitepaper gives an overview of BRASS and then describes the Isode strategy and solution for this area. It looks at how Isode’s products can support the protocols and interoperability for currently deployed BRASS systems and move them forward to state of the art capabilities that extend the services offered over BRASS.
  • Icon 5066 & Isode’s Strategy for Modem Independent Application Deployment over HF Radio
    This whitepaper describes Icon 5066, which is a server that implements the NATO STANAG 5066 link level protocols, which sit between HF modem and Applications. Applications access Icon 5066 using the STANAG 5066 SIS protocol over TCP. Icon 5066 is the first member of Isode’s Icon (Isode Constrained Networking) product family. This paper shows how Icon 5066 fits with Isode’s strategy of supporting applications running over HF Radio.