The IP Address Affinity technique for load balancing, also known as Source IP Affinity, is a method used to ensure that all requests from a particular client are directed to the same server as long as the session persists. This technique is particularly useful in maintaining session continuity, which is crucial for applications where user experience and transaction integrity are important, such as in online shopping carts or personalized user sessions.
How IP Address Affinity Works
IP Address Affinity operates by using the source IP address of incoming requests to determine which server will handle the request. When a client first connects to a service that uses IP Address Affinity, the load balancer hashes the client's IP address and uses this hash to select a server from the pool of available servers. Subsequent requests from the same IP address are directed to the same server, based on the assumption that the hash of the IP address will consistently route to the same server.
Advantages of IP Address Affinity
Session Persistence: This method ensures that a user's session is maintained on a single server, which can be critical for applications that maintain state information or session data across multiple requests.
Simplicity: IP Address Affinity is relatively easy to implement as it does not require any specific configuration on the client's side or within the application code.
Efficiency: Reduces the need for session data synchronization across servers, which can enhance performance and reduce server load.
Limitations of IP Address Affinity
IP Address Changes: If a user's IP address changes during a session, perhaps due to switching networks or using a mobile device, the session persistence can be lost, and the user may be directed to a different server.
NAT (Network Address Translation): In environments where many users are behind the same NAT, they appear to the load balancer as a single IP address. This can lead to uneven load distribution, as many reque...
