Direct web switch routing with state migration, TCP masquerade, and cookie name rewriting

Abstract

Existing layer 4 load balancers are content-blind and often have difficulty in redirecting HTTP requests. to the appropriate server in the session manner. Layer 7 load balancers, also referred to as web switches, are content-aware and support session persistence. However, most web switches employ a bi-direction architecture, which means both request and response traffic must both pass through the load balancer. This makes a web switch become a bottleneck easily. In this paper, we present a direct routing architecture to prevent response traffic from passing through the web switch. Our solution is highly scalable in the number of back-end servers. In addition, two simple but effective mechanisms, one-packet TCP state migration and cookie name rewriting to packet filter, are presented to support persistent connection and session persistence. Through the external benchmark, we prove that our system outperforms existing solutions. The internal benchmark investigates the bottlenecks of our system and suggests the future improvement.