Latency Improvements for ISPs

ECS Functionality (EDNS Client Subnet) in BIND9

The EDNS Client Subnet (ECS) is an extension of the DNS protocol that allows partial information of the end user’s IP address to be included in DNS queries sent to authoritative servers. This functionality is crucial for CDNs (Content Delivery Networks) to provide more precise and optimized responses based on the user’s geographic location.

Planisys PDNS natively offers ECS to enhance the latency and browsing experience for the end user.

🌍 How Does ECS Work?

When an ISP user performs a DNS query, it is resolved by a Planisys recursive resolver. Without ECS, the CDN (e.g., Netflix, Facebook, Instagram, Akamai) only sees the ISP’s recursive resolver IP, which can lead to less efficient responses because the CDN server assumes the resolver’s location is the same as the user’s, which is not always true.

It is important to clarify that the Planisys resolver may be located in the USA, but it informs, for example, Netflix’s CDN that the response should be directed to a client in Argentina.

In other words, it tells Netflix to return the closest IP available for www.netflix.com to the network of the user who made the request.

With ECS enabled, the Planisys resolver adds a fragment of the end user’s IP address to the DNS query sent to the authoritative server. This fragment typically includes the network prefix, allowing the CDN to more accurately identify the user’s geographic location and respond with the IP of the nearest or best-performing content server.

🔍 Example of Information Added to the EDNS Packet

Suppose an ISP user with IP 190.216.31.199 performs a query for www.ejemplo.com. Without ECS, the DNS packet sent by the Planisys resolver to the CDN might look like this:

DNS Query without ECS:

Query: www.ejemplo.com

Client visible to the CDN: IP of the Planisys resolver (e.g., 209.51.169.60)

With ECS enabled, the query will include an additional field in the EDNS extension, indicating the user’s IP prefix.

DNS Query with ECS:

Query: www.ejemplo.com

“Client visible to the CDN:”

IP of the Planisys resolver (209.51.169.60)

ECS Prefix: 190.216.31.0/24

This prefix (/24 in IPv4 or /56 in IPv6) allows the CDN to identify the user’s geographic region without exposing their full IP, maintaining a balance between optimization and privacy.

Key Benefits for ISPs

Network Performance Optimization

✨ Lower latency: CDNs respond with servers closer to the end user, reducing response time.

💻 Better bandwidth utilization: Traffic diversion to geographically distant locations is avoided.

Reduction of Operational Costs

💼 Less international traffic: By routing traffic to local or regional servers, IP transit costs on international links are minimized.

🌐 Optimization of peering infrastructure: Improves the efficiency of interconnection agreements with other operators and content providers.

Improvement in End User Experience

⏳ Improved loading speed: Users experience faster loading times in streaming services, online gaming, and cloud applications.

⚖️ Connection stability: Reduction in performance fluctuations, especially during peak demand periods.

Competitive Advantage for the ISP

💪 Better quality perception: Users associate faster and more stable browsing with the quality of the ISP’s service.

🔍 Differentiation capability: ISPs that implement ECS can offer better optimized traffic agreements with content providers.

Flexibility and Control for the ISP

🔧 Ability to define the ECS prefix size to balance privacy and routing efficiency.

📊 Greater visibility into routing towards CDNs, allowing adjustments based on the ISP’s network topology.

✅ Conclusion

The implementation of ECS in BIND9 allows ISPs to significantly improve content delivery to end users, optimizing network performance and reducing operational costs. By enabling CDNs to make decisions based on the user’s actual location, speed, stability, and traffic efficiency are enhanced, resulting in a better customer experience and a competitive advantage for the ISP.