Enabling Renewed Innovation in TCP by Establishing an Isolation Boundary
Umar Kalim, Eric Brown, Mark K. Gardner, Wu-chun Feng · 2010
The growth of the Internet has ushered in and established the “Information Age. ” However, its success has also arguably increased the difficulty of incorporating innovative changes that are needed to develop further functionality for next-generation networked applications. From the transport perspective, the desired functionality includes (1) supporting multiple network paths, (2) providing transport over hybrid networks (e.g., using both packet- and circuit-switched networks), and (3) decoupling upper-layer services from endpoint-naming semantics. The need for functionality — such as transport composability — has been reiterated in recent research and leads to an apparent dilemma: TCP, the ubiquitous transport protocol, neither admits such functionality in its present form nor does it seem possible to add it without substantial modifications. Furthermore, radical changes — whether through incompatible extensions or by creating a completely new protocol — will not be easily accepted. In contrast to the apparent dilemma, we argue that a backward-compatible modification to TCP that supports increased functionality is possible without incurring significant burden in additional protocol exchange. The lightweight mechanism, built upon a set of TCP options, establishes an isolation boundary between TCP and the application. The boundary separates an application data stream from the TCP transport flow. Further, it provides for the establishment of a control channel that allows additional capabilities to be negotiated dynamically throughout the lifetime of the communication. In short, the mechanism provides a simple “hook ” into TCP with which new features can be realized. This increases the freedom to evolve TCP while maintaining compatibility, thereby facilitating incremental adoption.