Latency Improvements for ISPs
ECS (EDNS Client Subnet) Functionality in BIND9
EDNS Client Subnet (ECS) is an extension of the DNS protocol that allows partial information from the end user’s IP address to be included in DNS queries sent to authoritative servers. This functionality is key for CDNs (Content Delivery Networks) to provide more accurate and optimized responses based on the user’s geographic location.
Planisys PDNS offers native ECS support to improve 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 IP address of the ISP’s recursive resolver, which can lead to less efficient responses because the CDN server assumes that the resolver’s location is the same as the user’s location, which is not always true.
It is important to clarify that the Planisys resolver may be located in the USA, but it informs the Netflix CDN, for example, that the response should be intended for a client in Argentina.
In other words, it tells Netflix to return, for www.netflix.com, the IP address closest to the network of the user who made the query.
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 usually includes the network prefix, allowing the CDN to more accurately identify the user’s geographic location and respond with the IP address of the closest or best-performing content server.
🔍 Example of Information Added to the EDNS Packet
Suppose an ISP user with IP address 190.216.31.199 performs a query for www.ejemplo.com. Without ECS, the DNS packet sent by the Planisys resolver to the CDN could look like this:
DNS Query without ECS:
Query: www.ejemplo.com
Visible client for the CDN: Planisys resolver IP address (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
Visible client for the CDN:
Planisys resolver IP address (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 the full IP address, 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.
🌐 Peering infrastructure optimization: Improves the efficiency of interconnection agreements with other operators and content providers.
Improved End User Experience
⏳ Improved loading speed: Users experience faster loading times in streaming services, online gaming, and cloud applications.
⚖️ Connection stability: Reduced performance fluctuations, especially during periods of high demand.
Competitive Advantage for the ISP
💪 Better perception of quality: Users associate faster and more stable browsing with the quality of the ISP service.
🔍 Differentiation capability: ISPs implementing 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 CDN routing, allowing adjustments based on the ISP network topology.
✅ Conclusion
The implementation of ECS in BIND9 allows ISPs to significantly improve content delivery to end users by optimizing network performance and reducing operational costs. By enabling CDNs to make decisions based on the user’s real location, traffic speed, stability, and efficiency are improved, resulting in a better customer experience and a competitive advantage for the ISP.