Chapter 9 Flashcards
Internet hierarchical structure
Tier 1 - ISPs. Provide service to customers and sell access to their 2 and 3
Tier 2- ISPs. Connect with tier 1, provide service to customers and sell access to local ISPs
Tier 3- ISPs. Connect to tier 1&2. Sell access to individuals
The internet
Network of networks
Unrestricted applications and contents
Network access points
NAPs- connect tier 1 ISPs together
Sometimes large tier 2&3 ISPs have access points
About a dozen NAPs in the US
Metropolitan area exchanges
MAEs
Connection tier 2 ISPs together
Peering
ISPs at the same level usually don’t charge each other for exchanging messages
Connecting to an ISP
Done through POP (point of presence)- a place where ISP provides service to its customers
Individual users- go through DSL or cable
Corporate users- access POP through using T-1, T-3, OC-3 provided by common carriers ( cost = ISP charge + circuit charge)
Internet backbone circuits
Becoming circuits for national ISPs using OC48&192(10gbps)
Rapidly growing
NAPS and MAEs becoming bottlenecks
Digital subscriber line
DSL uses customer premises equipment CPE Point to point technology High speed data over telephone lines Limited capacity 4khz Uses line splitter to split phone and DSL modem
Asymmetric DSL
Most common
Uses division multiplexing
Uses 3 FDM channels frequency division multiplexing
1.5 Mbps downstream ; 384 Kbps upstream
Cable modems
Digital service offered by cable television companies
Uses hybrid fiber coax
Uses shared multiplying circuits
150 Mbps down ; 100 Mbps upstream theoretically
1-10 Mbps down ; .25-1 Mbps upstream
Fiber to the home
Dedicated point to point fiber optics
Optical unit network at customer sit acts as an Ethernet switch Nd router
10-100 Mbps down. 1-10 Mbps up
15;4 most common
WiMAX
Wireless standard developed to connect Ethernet LANs
Can be fixed or …mobile wireless (4G)
Common data rare of 40 Mbps
