Application layer load balancing

LVS is a flexible framework for load balancing and the fact that it is implemented within the kernel makes it a high-performance solution since it does not require context switches and data transfer between user-space programs and the kernel. The fact that it works at the TCP or UDP protocol level also makes it application-agnostic and allows you to use it with any application service.

However, its lack of application protocol awareness is also its greatest weakness because it means that it cannot perform any protocol-specific optimizations. For example, one obvious way to improve performance for applications that may return the same reply to multiple users is to cache replies. LVS operates with TCP connections or UDP streams, so it has no way to know what a request or a reply looks like in any application layer protocol – it simply does not inspect TCP or UDP payloads at all.

Additionally, many modern application layer protocols are encrypted...