Configuring Network Adapter Teaming on Terminal Bus vs Plant Bus in SIMATIC PCS 7

In SIMATIC PCS 7, Network Adapter Teaming (NIC Teaming) is permitted and officially supported only on the Terminal Bus using standard commercial/industrial Ethernet adapters. Teaming two physical network ports on the Terminal Bus establishes a single virtual network adapter with one common IP address, providing automatic link redundancy and load balancing (e.g., using Intel PROSet Switch Fault Tolerance or Adaptive Load Balancing). Conversely, NIC Teaming is strictly prohibited on the Plant Bus when utilizing Industrial Ethernet communications processors (CP 1623 / CP 1628) or standard ISO/Named Connections. Redundancy on the Plant Bus is achieved at the communication layer using S7-REDCONNECT with dual distinct IP/MAC addresses or via Parallel Redundancy Protocol (PRP).

Executive Summary

High-availability network topologies in SIMATIC PCS 7 require physical cable and switch redundancy across both the Terminal Bus (connecting Engineering Stations, OS Servers, and OS Clients) and the Plant Bus (connecting OS Servers to AS controllers). A frequent design inquiry is whether physical network adapter teaming—combining two physical Ethernet ports into a single logical IP interface—can be implemented uniformly across both buses. While NIC Teaming is fully supported on the Terminal Bus to provide transparent physical link failover, applying teaming to Plant Bus communications processors breaks the SIMATIC NET driver stack and violates S7 fault-tolerant communication architecture. Understanding these network boundary rules guarantees compliant, robust plant connectivity.

Architecture and Fundamental Mechanics

The communication architecture of SIMATIC PCS 7 segregates administrative supervisory traffic from deterministic controller communication:

The Terminal Bus Architecture (NIC Teaming Supported):
* The Terminal Bus carries WinCC client-server traffic, SQL database synchronization, and engineering downloads using standard TCP/IP protocols (RPC, DCOM, SMB).
* Physical link redundancy is implemented using vendor NIC Teaming software (such as Intel PROSet / Intel Advanced Network Services - ANS or Windows Server Teaming).
* Two physical ports (e.g., onboard Intel I210/I219 Gigabit adapters) are joined into a single Team adapter with one shared IP address and subnet mask (e.g., 192.168.1.10/24).
* Teaming modes such as Switch Fault Tolerance (SFT) or Adaptive Load Balancing (ALB) automatically fail over traffic within milliseconds if a cable, transceiver, or switch port disconnects, without dropping WinCC client sessions.
The Plant Bus Architecture (NIC Teaming Prohibited):
* The Plant Bus connects OS Servers and Engineering Stations to S7-400H / CPU 410-5H controllers over Industrial Ethernet.
* For high-performance, fault-tolerant communication, OS Servers utilize specialized communications processors (CP 1623 or CP 1628) running the SIMATIC NET Hardnet driver stack.
* The communication protocol is S7-REDCONNECT, which manages four cross-coupled redundant communication paths in software over ISO Transport or ISO-on-TCP (RFC 1006).
* Each CP 1623 maintains its own independent MAC address and unique IP address (e.g., CP 1 on 192.168.0.10 and CP 2 on 192.168.2.10). Applying Windows/Intel NIC Teaming to CP 1623 cards disables the Hardnet NDIS filter driver and permanently breaks S7-REDCONNECT handshakes.
Recommended IP Subnet Allocations:
* Siemens mandates strict subnet isolation between the buses: the Terminal Bus and Plant Bus must never share the same IP subnet, physical cabling, or broadcast domain.
* Standard practice: Plant Bus Subnet 1 = 192.168.0.0/24, Plant Bus Subnet 2 = 192.168.2.0/24, Terminal Bus = 192.168.1.0/24.
Hardware Platform Form Factors (SIMATIC IPC):
* Dual CP 1623 cards require full-height PCI-Express x1 slots with adequate thermal spacing.
* A compact 19-inch rack PC like the SIMATIC IPC 547G/547J has limited PCIe slot layout for two long PCIe cards alongside modern graphic cards.
* For dual CP 1623 plus redundant onboard LAN, the SIMATIC IPC 647E (2U rack) or SIMATIC IPC 847E (4U rack) is recommended.

Step-by-Step Implementation Procedure

Follow these procedures to configure Terminal Bus teaming and Plant Bus redundancy correctly:

Configure NIC Teaming on the Terminal Bus:
* In Windows Server or Windows 10/11 Enterprise on the OS Server / ES, open the Intel PROSet Adapter Configuration Utility or Windows NIC Teaming Manager.
* Select the two physical network adapters assigned to the Terminal Bus (e.g., onboard LAN 1 and LAN 2).
* Click Add to Team and create a new team named Terminal_Bus_Team.
* Select Teaming Mode: Switch Fault Tolerance (SFT) (if connected to redundant physical switches) or Adaptive Load Balancing (ALB).
* Open Windows Network Connections, locate Terminal_Bus_Team, open Properties > Internet Protocol Version 4 (TCP/IPv4).
* Assign the static Terminal Bus IP address, subnet mask, and DNS (e.g., IP 192.168.1.10, Subnet 255.255.255.0).
Configure Independent Adapters on the Plant Bus (CP 1623):
* Install two physical CP 1623 cards into PCIe slots of the SIMATIC IPC (e.g., IPC 647E/847E).
* Do NOT enable NIC Teaming for these adapters.
* Open Windows Device Manager; verify both CP 1623 cards appear under SIMATIC NET.
* Assign distinct, non-overlapping IP addresses to each CP 1623 in Windows (or leave purely on Layer 2 MAC addresses if using ISO protocol):
- CP 1623 (Slot 1): 192.168.0.10, Subnet 255.255.255.0 (Plant Bus Net A)
- CP 1623 (Slot 2): 192.168.2.10, Subnet 255.255.255.0 (Plant Bus Net B)
Configure S7-REDCONNECT in NetPro:
* In SIMATIC Manager, open the OS Server PC Station in HW Config.
* Insert two CP 1623 modules into the PC Station virtual rack matching their physical slot numbers.
* Connect CP 1 to Industrial Ethernet (1) and CP 2 to Industrial Ethernet (2).
* Open NetPro, select the WinCC Application, and insert a new Fault-tolerant S7 connection to the S7-400H / CPU 410-5H cluster.
* NetPro automatically configures the 4-way redundant path across both CPs.
Download PC Station and NetPro Configuration:
* Save and compile NetPro.
* Download the PC Station configuration via Station Configuration Editor.
* Verify that both CP 1623 cards display RUN status in Station Configuration Editor.

Verification

Test Terminal Bus redundancy by initiating a continuous ping from an OS Client to the OS Server's teamed IP (ping -t 192.168.1.10). Unplug one physical network cable from the Terminal Bus NIC; confirm that zero packets are dropped and WinCC faceplates remain responsive. For the Plant Bus, observe S7-REDCONNECT in the WinCC Channel Diagnosis tool (WinCC Channel Diagnosis); verify that disconnecting Plant Bus A causes an instantaneous switch to Plant Bus B without loss of AS process communication.

Limitations and Operational Precautions

Never combine a Terminal Bus adapter and a Plant Bus adapter into the same NIC Team. Never connect the Terminal Bus and Plant Bus to the same unmanaged network switch or unsegregated VLAN, as broadcast storms and multicast traffic will saturate the AS communications processors.

Engineer FAQ

Can I use NIC Teaming on the Plant Bus if using standard network cards (Softnet)?

No. Even with Softnet (BCE), SIMATIC NET does not support teaming on the Plant Bus. Fault-tolerant connections require distinct IP addresses managed by the S7 protocol.

Why is IPC 547 not recommended for dual CP 1623?

The mechanical PCIe slot layout and cooling constraints of the IPC 547 make installing two full-length CP 1623 cards alongside high-end graphics cards difficult. The IPC 647E or 847E provides dedicated PCIe slot space.

Does Terminal Bus teaming require special network switch configuration?

Switch Fault Tolerance (SFT) does not require any special switch configuration (such as LACP) and works across two completely independent, unstacked switches.

What is the difference between SFT and ALB?

SFT uses an active/standby model providing link redundancy only; ALB balances transmit traffic across both physical ports while providing receive redundancy via SFT.