Asymmetric TCP splicing for content-based switches

A content-based switch makes forwarding decisions (server selections), based on application layer information, and forwards data in the application layer. After making forwarding decisions, existing content-based switches increase their forwarding performance by TCP splicing, which releases them from maintaining TCP endpoints and allows them to forward data by packet forwarding. However, TCP splicing prevents the switches from using the application layer information for forwarding decisions. Thus existing content-based switches cannot hand off pipelined HTTP transactions, which can greatly reduce client perceived latencies. This paper proposes asymmetric TCP splicing and a method to hand off HTTP transactions between servers. Asymmetric TCP splicing allows the content-based switches to use all the application layer information in the TCP data stream from clients to servers, although it allows the switches to forward the TCP data stream from servers to clients by packet forwarding. The proposed handoff method, which uses a TCP half-close to detect the boundary of server responses, enables content-based switches to support pipelined HTTP transactions in combination with asymmetric TCP splicing. Our evaluation shows that if a content-based switch supports pipelined HTTP transactions by asymmetric TCP splicing and our proposed handoff method, client-perceived latencies can be reduced substantially.