送交者: steven 于 2004-12-30, 15:48:09:
回答: steven, how TCP/IP traffic runs on top of... 由 enable 于 2004-12-30, 14:01:57:
routing or anything. IP, internet protocol, deals with how packets are routing among different networks. Typically, you have your LAN, and your LAN has one or multipal gateways connected to the internet backbone. The backbone node, during ARPANET time it was called IMP, is basically a computer links to another node through lines leased from phone companies. Early days, those lines were only 56kbps.
In 1988, NSFNET took over what ARPANET and built the backbone, which included a couple supercomputer centers located in San Diego, Boulder, Champaign, Pittsburgh, Ithaca and Princeton, and some reginal network. It was a big success. Then NSFNET worked on its version 2 backbone, which initially leased Fiber channels at 448 kbps from MCI, in 1990, this backbone was upgaded to 1.5Mbps.
Today, the nodes are much more powerful, and the line speed is much faster, however, it remains the same, that individial computers connects to a router, either DSL or cabel switch, or LAN routers which connects to firewall, then those switches connect to other backbone nodes through leased line, which mostly provided by phone companies, or sat. link, and everyone of these links are peer-to-peer link. These links can be sonet, ATM, frame relay or some other technology.
For voice, at the end of your phone connects to a vocoder which digitized your voice into digital data, and sent through the trunk as packets. There are QoS in place to ensure paid services get through first. It is not like there is a fibre channel from one end to the other end for either voice or data user, there are hups in between, and the hup processors implement the QoS strategy to ensure service.