SIX Interbank Clearing – Swiss Instant Payments powered by Aeron Cluster

A Look at SIX’s Journey with Aeron

Predictable latency and resilience are key in today’s financial landscape, nowhere more so than in a central bank scenario.

This blog post dives into the use case presented by Stefan Ferstl, Senior Architect from SIX Interbank Clearing at the Aeron Meetup in London in May 2024. It focuses on the challenges and requirements of instant payments in a central bank setting, and how SIX leveraged Aeron Cluster to achieve their rigorous performance and resiliency goals.

Instant Payments in Switzerland

  • SIX, a Swiss company, operates the Swiss Interbank Clearing (SIC) system on behalf of the Swiss National Bank which is Switzerland’s central payment system.
  • The SIC system processes both large-value transactions and retail payments, handling trillions of CHF annually.
  • To enable instant payments, SIX needed a solution that ensured predictable latency, data integrity, and 24/7 operations.

← Watch SIX Interbank Clearing at the Aeron Community MeetUp

 

Interbank Settlement – What is special about it?

  • The SIC System keeps a settlement account for each connected bank.
  • The settlement accounts are provisioned with Central Bank money by the Swiss National Bank.
  • Settlement can only occur when the amount is fully covered on the debited account (liquidity control). It is done in real-time, irrevocably and final for each individual payment.

 

Technical challenges of enabling Instant Payments

  • Real-time Processing: Transactions need to be settled within seconds, unlike the traditional business-day processing of the SIC system. Guaranteed processing time of a max. 10s end-to-end and max. 200ms within SIC were required.
  • Performance: The SIC systems needs to handle 35 million payments per day with peaks of ~2000 payments/s over 1h without any performance tuning.
  • Data Integrity: Transaction data must be preserved under any circumstances, even in case of data center failures.
  • 24/7 Operation: The system needs to be available and operational all year round, without interruption.

SIX Instant Payments System Overview Diagram - Aeron Messaging

 

Why Not the Existing Architecture?

While Six Interbank Clearing considered using the existing database-centric architecture, it posed several challenges:

  • Extensive performance tuning would be required from the outset.
  • Upgrades would be complex due to the 24/7 operating model.
  • Introducing redundancy for fault tolerance would necessitate significant changes.

SIC5 Instant Payments System at SIX - Aeron Messaging

 

Aeron Cluster – predictable latency & fault tolerance at your fingertips

SIX Interbank Clearing opted for a new architecture built on Aeron Cluster to address the challenges of instant payments. Here’s how it works:

  • Processing Cluster: Handles core settlement logic for fast and reliable transactions.
  • State Management: Account balances are temporarily stored in-memory and updated by the application. Daily snapshots are taken for persistence.
  • Processing Gateway: Handles secure communication with participants and performs stateless validation and authorization of payments.

 

Benefits of Aeron Cluster

  • Data Durability & Resilience: Geographically distributed cluster ensures data integrity even in case of data center outages.
  • Predictable Performance: Achieved without any performance tuning or optimization needs, meeting the real-time processing requirements.
  • Scalability: The cluster can be easily extended for future growth (e.g., six-node setup).
  • Support: SIX Interbank Clearing received exceptional support from the Aeron team when implementing Aeron.

 

Lessons Learned implementing Instant Payments with Aeron

  • 24/7 Operations: Maintaining a constantly running system requires meticulous planning and testing of upgrades.
  • Monitoring Challenges: Shifting from a database-centric approach necessitated development of new tools for system insights.

 

What’s next?

SIX’s success story demonstrates the effectiveness of Aeron Cluster in powering real-time payments use cases. The solution delivers the required speed, data integrity, and operational efficiency, paving the way for a future of faster and more reliable payment processing in Switzerland:

Stefan Ferstl

Stefan Ferstl
Senior Architect
SIX Interbank Clearing

Stefan Ferstl is a computer scientist with a focus on the payments industry. After earning a CS degree in Switzerland (2006), he joined SIX Group as a software engineer in credit card transaction processing. He later started work on the SIC platform and is now heading up the development team as its senior architect.

 

SIX logo

SIX, a Swiss company, operates the Swiss Interbank Clearing (SIC) system on behalf of the Swiss National Bank which is Switzerland’s central payment system. Find out more about Payment Services for the Swiss Financial Center.