Home → Magazine Archive → November 2015 (Vol. 58, No. 11) → Technical Perspective: Treating Networks Like Programs → Abstract

Technical Perspective: Treating Networks Like Programs

By George Varghese

Communications of the ACM, Vol. 58 No. 11, Page 112

Why are my packets being dropped? Why does my Internet connection keep resetting? Programmers developing software have access to a panoply of tools including compilers, debuggers, static and dynamic checkers. Unfortunately, network operators have access to only crude tools such as TraceRoute and Ping. These tools have remained unchanged for decades while networks have grown increasingly complicated: load balancers spread traffic using unknown hash functions, and firewalls interdict messages based on cryptic rules that human operators enter, sometimes incorrectly. In a world of services accessed from tablets and mobile devices, network failures are a debilitating source of operational expenditures.

On the surface, networks with their collections of routers, switches, network interface cards, and cabling do not resemble code. But one can view the entire network as a "program" that takes packets from the input edges of the network and outputs packets to the output edge after possibly rewriting the packet. The forwarding table at routers can, for instance, be viewed as a large Switch statement across destination addresses.


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