158 .235 Lecture : Business Data Communications and Networking Chapter 10 - The Internet
Document Summary
Made up of thousands of networks of national and state government agencies, and non-profit organizations and for-profit companies. Provide services to their customers and sell access to tier 2 and 3 isps. Provide access to their peers (other national isps) Provide services to their customers and sell access to local isps. Provide access to their peers (other regional isps) Connected to tier 1 or 2 isps. Provide access to their peers (other local isps) Connect tier 1 isps together. (sometimes large tier 2 and 3 isps too) Peering isps at the same level usually do not charge each other for exchanging messages. However higher level isps charge lower level isps. Tier 1 charges tier 2 and tier 3. Users connect to an isp through one of the isps point of presence. Corporate users have a cost of isp charges + circuit charges. Backbone for national isps uses oc-48 and oc-192, becoming more common.
