Commercial Internet eXchange

Commercial Internet eXchange. The Commercial Internet eXchange (CIX) was a pivotal early Internet exchange point established in 1991 to enable peering among the nascent commercial Internet service providers in the United States. It was created as a cooperative, neutral interconnection facility to bypass the restrictive Acceptable Use Policy of the government-subsidized NSFNET backbone, thereby allowing unrestricted commercial traffic. The CIX is widely credited with catalyzing the competitive commercial Internet by establishing a model for open interconnection that became foundational to the modern global network.

History

The genesis of the organization stemmed from growing frustration among early commercial network operators like PSINet, UUNET, and CERFnet with the National Science Foundation's NSFNET and its Acceptable Use Policy, which prohibited commercial data traffic. In early 1991, executives including William L. Schrader of PSINet and Rick Adams of UUNET began discussions to form a cooperative exchange. The founding agreement was signed in August 1991 by these three carriers, often called the "CIX Three," with the first router installed in Santa Clara, California in December 1991. A key legal and policy milestone was reached in 1992 when the Federal Networking Council affirmed that traffic crossing the infrastructure did not violate the NSFNET policy, effectively legitimizing the commercial Internet. Its influence began to wane in the mid-1990s with the rise of private peering agreements and other major exchange points like MAE-East operated by MFS Communications, leading to its eventual operational sunset.

Function and operation

Its primary function was to provide a neutral, shared switching fabric where member Internet service providers could exchange IP traffic with one another without restrictive contracts or financial settlements. This "sender keeps all" settlement-free peering model was a radical departure from the tariffed structures of traditional telecommunications carriers like AT&T. Operation was governed by a simple multilateral agreement where each member connected a router to the shared Ethernet LAN, enabling direct routing of traffic between their respective autonomous systems. This arrangement eliminated the need for traffic to transit the NSFNET backbone for inter-provider delivery, reducing latency and cost while fostering a more robust and redundant network topology.

Technical infrastructure

The initial technical core was a single FDDI ring located at a facility in Santa Clara, California operated by Advanced Network & Services, which later moved to Metropolitan Fiber Systems sites. The core interconnection technology evolved from FDDI to high-speed Ethernet LAN segments, specifically 10BASE-FL and later 100BASE-FX. Each member Internet service provider connected their border router to this shared LAN via an interface card, establishing BGP sessions with a route server or directly with other peers. The route server, a significant innovation, simplified the BGP configuration for members by distributing global routing table information, a concept later refined at exchanges like the London Internet Exchange.

Impact and significance

Its impact on the evolution of the global Internet was profound and immediate. By providing the first major alternative to the NSFNET backbone, it broke the government's monopoly on Internet infrastructure and proved the viability of a competitive, commercial market. The "CIX Agreement" and its settlement-free peering principle became the de facto standard for Internet exchange points worldwide, influencing the design of critical institutions like the Amsterdam Internet Exchange and Japan Internet Exchange. It directly enabled the explosive growth of Internet service providers in the early 1990s, paving the way for companies like Netcom and EarthLink, and was essential for the early commercial success of World Wide Web pioneers.

Governance and membership

Governance was initially informal, guided by the founding members PSINet, UUNET, and CERFnet, but quickly formalized into a member-elected board. Membership was open to any entity that operated an Internet backbone and agreed to the multilateral peering agreement, with fees covering the costs of the shared infrastructure. Notable early members beyond the founders included ANS CO+RE, NEARNET (with John Curran), and later SprintLink. The organization incorporated as a non-profit trade association in 1993, but its governance model faced challenges as the industry scaled, leading to disputes over peering policies with larger carriers like MCI Communications, which accelerated the move toward private interconnection. Category:Internet exchange points Category:Internet in the United States Category:Organizations established in 1991