Network redundancy (ring topology) in SCADA systems - Step-by-Step Execution

Process Flow - Network redundancy (ring topology)

Start: Network Setup

↓

Connect devices in a ring

↓

Data flows in both directions

↓

Detect link failure?

No→Continue normal operation

Yes↓

Switch data flow direction to bypass failure

↓

Maintain network communication

↓

End

The network devices connect in a circle. Data can flow both ways. If one link breaks, data reroutes the other way to keep communication alive.

Execution Sample

SCADA systems

DeviceA <-> DeviceB <-> DeviceC <-> DeviceD <-> DeviceA
If link DeviceB-DeviceC fails:
  Data flows DeviceB -> DeviceA -> DeviceD -> DeviceC

Shows devices connected in a ring and how data reroutes when one link fails.

Process Table

Step	Event	Link Status	Data Flow Direction	Network State
1	Initial setup	All links up	Bidirectional	Normal operation
2	Data transmission	All links up	Bidirectional	Data flows normally
3	Link failure detected (DeviceB-DeviceC)	DeviceB-DeviceC down	Bidirectional	Partial failure detected
4	Switch data flow	DeviceB-DeviceC down	Reverse direction around ring	Data rerouted successfully
5	Network stable	DeviceB-DeviceC down	Reverse direction around ring	Communication maintained
6	Link repaired	All links up	Bidirectional	Normal operation restored

💡 Link repaired, network returns to normal bidirectional flow

Status Tracker

Variable	Start	After Step 3	After Step 4	After Step 6
Link_DeviceB-DeviceC	Up	Down	Down	Up
Data_Flow_Direction	Bidirectional	Bidirectional	Reverse around ring	Bidirectional
Network_State	Normal	Partial failure	Rerouted	Normal

Key Moments - 3 Insights

Why does data flow switch direction when a link fails?

Because the ring topology allows data to travel both ways, switching direction bypasses the broken link and keeps communication alive, as shown in steps 3 and 4 of the execution table.

What happens if the failed link is not repaired?

The network continues to operate by rerouting data in the opposite direction, maintaining communication but with one link down, as seen in steps 4 and 5.

Is the network completely down when a single link fails?

No, the ring topology provides redundancy so the network stays up by rerouting data, demonstrated in step 4 where data flow changes direction.

Visual Quiz - 3 Questions

Look at the execution table, what is the data flow direction at step 4?

A Bidirectional

B Reverse direction around ring

C Unidirectional forward

D No data flow

💡 Hint

Check the 'Data Flow Direction' column at step 4 in the execution table.

At which step does the network detect a link failure?

A Step 3

B Step 2

C Step 5

D Step 6

💡 Hint

Look for 'Link failure detected' event in the execution table.

If the link DeviceB-DeviceC remains down, what is the network state at step 6?

A Normal operation

B Network down

C Partial failure

D Data flow stopped

💡 Hint

Refer to the 'Network State' variable in variable_tracker after step 4 and step 6.

Concept Snapshot

Network redundancy with ring topology:
- Devices connect in a circle.
- Data flows both directions.
- If one link fails, data reroutes the other way.
- Keeps network communication alive.
- Repairs restore normal bidirectional flow.

Full Transcript

Network redundancy using ring topology means devices connect in a circle. Data can flow both ways around the ring. If one link breaks, the system detects the failure and switches data flow direction to bypass the broken link. This keeps communication alive without interruption. When the link is repaired, the network returns to normal bidirectional flow. This method ensures the network stays up even if one connection fails.