HVAC Control in the New Millennium.pdf - HVAC.Amickracing

HVAC Control in the New Millenniumbe upgraded from the central offices to the infrastructure.Conventional circuit switching will not do in the 21st centuryand boosting bandwidth may require gear like dense wavelength-divisionmultiplexers (DWDMs). The new technologies also includeterabit routers.Another factor is the Internet, which dumps a huge amount ofdata onto public networks. Data on some backbones is growing at800% annually. In 1996, international Internet traffic was so low comparedwith voice that it was scarcely a ripple, but in only 18 monthsit rocketed up to exceed voice.This data explosion is forcing carriers to curb their investmentin circuit-switched equipment. The Internet is also forcing carriers tostandardize on IP (Internet Protocol).The old public network was for voice. Everything is standardizedon 64 kbit/s voice channels. Voice does not need 64-kbit/s anymore, it can be compressed without sacrificing quality. Trying to accommodatebursty packet data on fixed circuits is fundamentally inefficient.Most capacity remains idle much of the time.Each data service runs over lots of overlaid networks. This resultsin inflated service charges. In the new public network, trafficwill be streamed into a single fiber that can handle up to 80 Gbit/s.There are already predictions of even faster optical switches.New types of equipment include monster RASs (remote accessservers) that terminate thousands of analog calls from analog modems.The new public network is supposed to be packet-or cellswitched.But, the old public net will be part of the infrastructure foryears with its old circuit-switched infrastructure.In the new network, switches read packet and cell headers. Theyrefer to a directory that provides data type and encryption. More Webservers will be shifted to the network as well as hardware and softwarethat oversee access rights. Other servers will be used for newapplications like e-commerce. Users will specify whatever capacitythey want. Provisioning is faster because switches can be configuredremotely.The new public net also eliminates overlays. Carriers will shiftfrom existing data services to a single underlying infrastructure,eliminating duplicated resources.Sonera is Finland’s main long distance ATM backbone. It willinitially feature three levels of data service. ATM is used by other car-©2001 by The Fairmont Press, Inc. All rights reserved.