Wide-Area Networks

WAN and LAN Topologies
1. A hub-and-spoke WAN design, using leased lines, reduces the number of leases lines, while still providing a way for packets to reach all sites.
2. Packet-switched services create the possibility of a different topology called a multipoint WAN topology
3. A modern WAN point-to-point link uses a 2 pair (4-wire) circuit
T-Carrier System and TDM
1. Time-division multiplexing divides the time allowed for sending data on the high speed ink, by combining (plex) multiple slower speed channels
2. The T-Carrier System used DS0, DS1, and DS3 lines both to customer sites and between COs
3. The entire Telco system of using many TDM switches, many trunks, with many customer leased lines does not create a traffic jam of bits trying to move around
Telco Services
1. A voice call required one analog electrical circuit between the two phones
2. 2-wire local loop allowed a single electrical circuit into the home, which worked well for voice
3. Early telephone companies focused on voice telephone services, not on WAN services
Leased-Line WAN Links
1. With a leased line, expect to get basic service, the ability to send bits between two devices (typically routers)
2. The speeds must be a multiple of some specific number
3. A leased line stretches for hundreds or even thousands of miles

Zusammenfassung der Ressource

	Erstellt von pinedaluis8 vor mehr als 11 Jahre