Issue
Customers may encounter one or more of the following symptoms:
- Automation Server (AS) reports a communication alarm for the Enterprise Server (ES).
- Server-to-server bindings remain unresolved.
- ES displays an AS as online, while the AS reports communication issues with the ES.
- Communication issues occur after firewall changes, network segmentation, NAT implementation, cellular router deployment, or system upgrades.
- Communication problems are observed despite successful ping tests or apparent server connectivity.
Product Line
EcoStruxure Building Operation
Environment
- EcoStruxure Building Operation
- Enterprise Server (ES)
- Automation Server Premium (AS-P)
- Automation Server Bundled (AS-B)
- HTTPS server communications
- TCP server communications
Cause
A common misconception is that server communications are functioning correctly if the Enterprise Server can communicate with an Automation Server and reports it as online.
In EcoStruxure Building Operation, server-to-server communication is inherently bidirectional. Both servers must be capable of exchanging information as part of the server communication relationship.
When firewall rules, routing policies, NAT configurations, or network infrastructure prevent one server from communicating with the other, communication alarms, unresolved bindings, and other synchronization issues may occur even while the servers appear online.
The exact communication behavior depends on the EBO version and communication protocol being used.
Refer to the EBO EcoStruxure BMS Server Communication Webhelp topic for guidance on the recommended protocols for each EBO version.
Resolution
EBO 5.x and Earlier
Prior to EBO 6.0, server communications used traditional CSP, HTTP, or HTTPS transport methods.
In these versions:
- Enterprise Servers initiate communications to Automation Servers.
- Automation Servers initiate communications to Enterprise Servers.
- Each server acts as both a client and a server.
- Both servers must be directly reachable across the network.
The following communication models require bidirectional network connectivity:
| Protocol | Default Port | Connectivity Requirement |
|---|---|---|
| TCP | TCP 4444 | Bidirectional |
| HTTP | TCP 80 | Bidirectional |
| HTTPS | TCP 443 | Bidirectional |
Because both servers actively establish connections, firewall rules and routing policies must allow communication in both directions.
EBO 6.0 and Later
Beginning with EBO 6.0, server communications over HTTPS were enhanced through the introduction of WebSocket technology.
This change was designed to improve communication efficiency and support architectures where direct inbound communication between servers may not be practical, including:
- Cloud-hosted Enterprise Servers
- NAT environments
- Segmented enterprise networks
With WebSocket communication enabled through HTTPS:
- One EBO server establishes a WebSocket connection to the other server.
- The WebSocket connection remains active as a long-lived TCP session.
- Both servers exchange information through the established session.
- Application-level communication remains fully bidirectional.
Although only one TCP session may be visible, communication continues to occur in both directions through the established WebSocket connection.
This allows server communications to function in network architectures where traditional bidirectional connection establishment would otherwise be difficult.
Important Notes
HTTPS (TCP 443)
When HTTPS communication is configured, EBO uses a WebSocket-based communication model.
Characteristics include:
- Persistent long-lived connection
- Bidirectional application communication
- Reduced connection establishment overhead
- Improved performance compared to repeatedly creating and closing sessions
- Better support for NAT and cloud-connected deployments
TCP(TCP 4444)
Traditional TCP communication on TCP 4444 remains available.
Characteristics include:
- Traditional connection model
- Requires bidirectional reachability
- Both servers must be capable of establishing communication with each other
- Does not use WebSocket transport
Organizations upgrading older systems may still have servers communicating over TCP 4444 even after upgrading EBO versions.
Multi-version systems
In Multi-version systems, it recommended to:
- use HTTPS for EBO 6.x or later servers and TCP for servers on older versions.
- set the protocol to HTTPS for child servers after upgrading them to EBO 6.x or later not before the upgrade, refer to Automation Servers Running EBO 3.2.4 Go Offline After Enterprise Server 7.1.2 Upgrade When Using HTT...
Troubleshooting Guidance
When investigating unresolved bindings or ES/AS communication alarms:
- Identify which protocol is being used between servers.
- Verify whether communication is configured for TCP 4444 or HTTPS 443.
- Confirm that firewall policies permit the required traffic.
- Verify routing paths between all EBO servers.
- Review NAT rules that may affect server communications.
- Check for network devices that terminate or time out long-lived connections.
- Perform Repair Server Communications after resolving network issues.
- Verify communication alarms clear and bindings return to a resolved state.
- You can check for possible server to server communication issues in WorkStation by creating an Alarm view with system alarm IDs filter “Communication failed” and “Server offline”.
- In WebStation V5 or later, you can use Diagnostics Server Communication List in WebStation
Additional Information
An Automation Server communication alarm referencing the Enterprise Server is a particularly important diagnostic indicator.
This alarm originates from the Automation Server and indicates that the Automation Server is experiencing difficulty communicating with the Enterprise Server. The Enterprise Server may still show the Automation Server as online because communication in one direction continues to function.
This asymmetric communication condition is frequently associated with:
- Firewall restrictions
- NAT translation issues
- Incomplete routing
- Network segmentation
- Cellular network deployments
- Improperly configured server communication protocols
Network design guidance
Understanding the underlying server communication model is often the key to diagnosing unresolved bindings and server communication alarms in complex network environments.
For recommendations on EBO network design and best practices refer to the following documents:
