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What is anycast?

What is anycast?

Anycast is a network addressing and routing method in which incoming requests can be routed to various locations or "nodes." In the context of a content delivery network (CDN), Anycast typically routes incoming traffic to the nearest data center with the capacity to process the request efficiently.


Understanding Anycast

Anycast is a technique that distributes incoming traffic across multiple data centers within a CDN. When a user requests a website, it is directed to the nearest data center that can efficiently process the request. This selective routing ensures the content is delivered faster, reducing latency and improving the overall user experience.

In the context of CDNs, Anycast is particularly useful for handling high traffic volumes, network congestion, and DDoS attacks. By distributing traffic across multiple data centers, Anycast ensures that no single server or data center becomes overwhelmed, preventing service interruptions and maintaining content availability.


How Anycast works

Anycast routing operates by associating multiple data centers with a single IP address. When a request is received, the anycast network determines the optimal data center to process the request based on various factors, such as network latency and proximity. The goal is to choose the data center closest to the requester, minimizing the distance the data needs to travel.


Benefits of an anycast network

Using an anycast network offers several benefits, especially in the context of CDNs:

Improved performance and latency

Anycast routing improves performance and reduces latency. Directing traffic to the nearest data center minimizes the distance data needs to travel, resulting in faster content delivery. This is particularly important for websites and applications that require real-time data updates or have interactive elements.


Load balancing and scalability

Anycast enables load balancing across multiple data centers. Instead of overwhelming a single server or data center with high traffic volumes, requests can be distributed across available data centers, each equipped with servers capable of processing and responding to incoming requests. This load-balancing capability enhances scalability, ensuring that the network can handle increasing traffic demands without service interruptions.


Resilience and DDoS mitigation

One of the advantages of Anycast is its resilience against DDoS attacks. DDoS attacks involve overwhelming a target server or network with massive traffic, rendering it inaccessible to legitimate users. Anycast mitigates this risk by distributing the attack traffic across multiple data centers. Suppose the capacity of the anycast network exceeds the attack traffic. In that case, the attack can be effectively absorbed, ensuring the availability of services.

Read more: What is a DDoS attack? 


Anycast and DDoS mitigation

DDoS attacks threaten online services, and CDNs are often targeted due to their function in content delivery. Various mitigation tools filter out some of the attack traffic when a DDoS attack occurs. Anycast then distributes the remaining attack traffic across multiple data centers, preventing any one location from becoming overwhelmed.

DDoS attacks typically utilize a botnet, a network of compromised computers, to generate massive traffic. Anycast's ability to absorb and distribute this traffic across multiple data centers makes it challenging for attackers to overwhelm the CDN's infrastructure.

Related: What is a botnet?


Setting up an anycast network

Implementing an anycast network requires careful planning and coordination. CDN providers must maintain network hardware, establish direct relationships with upstream carriers, and fine-tune their networking routes to ensure efficient traffic distribution.

See also: HIPAA Compliant Email: The Definitive Guide  

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