1.2 The network edge Flashcards
Name the categories of hosts.
Hosts (or end systems) are divided into clients and servers.
Categories of physical media.
- guided: the waves are guided along a solid medium.
- unguided: the waves propagate in the atmosphere and in outer space.
Access networks: Home. Name the types of access networks.
- DSL (digital subscriber line)
- Cable
- Fiber To The Home (FTTH)
- Satelite link
- Dial-up
Access networks: Enterprise&Home. Name the types of access networks.
- Ethernet
- WiFi
Access networks: Wide-area wireless acess. Name the types of access networks.
- 3G
- LTE
Describe DSL.
The home’s DSL modem takes digital data and translates it to high frequency tones for transmission over telephone wires to the Central Office (CO); the analog signals from many houses are translated back into digital format at the DSLAM (DSL Access Multiplexer).
The residential telephone line carries both data and traditional telephone signals simultaneously, which are encoded at different freqs:
- high-speed downstream channel: 50 kHZ to 1 MHz band
- medium-speed upstream channel: 4 kHz to 50 kHz band
- ordinary two-way tel. channel: 0 to 4 kHz band
ITU 2003:
- down: 24 Mbps.
- up: 2.5 Mbps
Residency must e located within 8-16 km from CO.
Describe Cable.
Fiber optics connect the cable head end to neighborhood-herd junctions, from which traditional coaxial cable is the used to reach individual houses nd apartments.
Each neighborhood junction typically supports 500 to 5000 homes.
in the telco’s CO.
Because both cable & coaxial cables are employed, it is often referred to as Hybrid Fiber Coax (HFC).
DOCSIS 2.0:
- down: 42.8 Mbps
- up: 30.7 Mbps
Describe Fiber To The Home (FTTH).
Two competing architectures:
- Active Optical Nets (AON)
- Passive Optical Nets (PON)
- AON is essentially switched Ethernet, which is discussed in Chapter 5.
- PON: each home has an Optical Network Terminator (ONT) which is connected by dedicated optical fiber to a neighborhood splitter. The splitter combines a number of homes (<100) into a single, shared optical fibre, which connects to an optical line terminator (OLT) in the telco’s CO.
Describe Satellite link.
speeds of more than 1 Mbps.
Describe dial-up.
a home modem connects over a phone line to a modem in the ISP.
56 kbps.
Describe Ethernet and WiFi.
LAN is used to connect an end system to the edge router.
Although there are many types of LAN techs., Ethernet is by far the most prevalent access tech. in corporate, univ. and home sets.
Users typically have 100 Mbps access to Ethernet switch.
Server may have 1 Gbps or even 10 Gbps.
WiFi 802.11: 54 Mbps.
Describe 3G and LTE.
- 3G: 1 Mbps
- LTE: 10 Mbps.
