Characterizing user‐level network virtualization: performance, overheads and limits

Abstract

AbstractConnectivity limitations in the current Internet have motivated the development of many overlay networking technologies that enable applications to transparently overcome such limitations. For easy development and deployment, overlay networks are typically implemented via a user‐level network virtualization software layer, often using high‐level languages. Existing solutions report performance that can keep up with slow wide‐area links—however, the question remains as to how overlay networks perform on new high‐speed Internet connections. This paper characterizes the performance of user‐level packet processing, which is at the core of most overlay networks implementations. To this end, building blocks of packet‐processing software are identified and characterized, and performance of IP forwarders developed in C and Java are compared through extensive measurements. Factors that affect the performance of overlay networks and limitations of existing solutions are characterized, providing insights on possible improvements. Experimental results show the following: to achieve maximum throughput, only a few microseconds (2–5) can be spent in virtual network processing; processing of small packets can limit TCP throughput; and overlays need to be carefully architected as encapsulation overheads can be substantial. Copyright © 2009 John Wiley & Sons, Ltd.