Chap_2 Flashcards
Customer Premises Equipment (CPE)
company uses WAN services from an ISP and uses a device called the CPE by renting or owning it and it is connecting the business to the carrier link.
Data Communications Equipment (DCE)
the DCE consists of devices that put data on the local loop. The DCE primarily provides an interface to connect subscribers to a communication link on the WAN cloud. converts user data into a WAN service provider acceptable signal and vice versa.
Data Terminal Equipment (DTE)
The customer devices that pass the data from a customer network or host computer for transmission over the WAN. The DTE connects to the local loop through the DCE
Demarcation Point
A point established in a building or complex to separate customer equipment from service provider equipment . The demarcation point is the place where the responsibility for the connection changes from the user to the service provider. When problems arise, it is necessary to determine whether the user or the service provider is responsible for troubleshooting or repair.
Local Loop
The actual copper or fiber cable that connects the CPE to the CO of the service provider.
Central Office (CO
The CO is the local service provider facility or building that connects the CPE to the provider network.
Toll network
This consists of the long-haul, all-digital, fiber-optic communications lines, switches, routers, and other equipment inside the WAN provider network.
Dialup modem
converts (i.e., modulates) the digital signals produced by a computer into voice frequencies that can be transmitted over the analog lines of the public telephone network. On the other side of the connection, another modem converts the sounds back into a digital signal (i.e., demodulates) for input to a computer or network connection.
Access server
Concentrates dialup modem, dial-in and dial-out user communications. Considered to be a legacy technology, an access server may have a mixture of analog and digital interfaces and support hundreds of simultaneous users.
Broadband modem
A type of digital modem used with high-speed DSL or cable Internet service. Both operate in a similar manner to the voiceband modem, but use higher broadband frequencies and transmission speeds.
CSU/DSU
Digital-leased lines require a CSU and a DSU. A CSU/DSU can be a separate device like a modem or it can be an interface on a router. The CSU provides termination for the digital signal and ensures connection integrity through error correction and line monitoring. The DSU converts the line frames into frames that the LAN can interpret and vice versa.
*Channel Service Unit/ Data Service Unit
WAN switch
A multiport internetworking device used in service provider networks. These devices typically switch traffic, such as Frame Relay or ATM and operate at Layer 2.
Router
Provides internetworking and WAN access interface ports that are used to connect to the service provider network. These interfaces may be serial connections, Ethernet, or other WAN interfaces. With some types of WAN interfaces, an external device, such as a DSU/CSU or modem (analog, cable, or DSL), is required to connect the router to the local service provider.
Core router/Multilayer switch
A router or multilayer switch that resides within the middle or backbone of the WAN, rather than at its periphery. To fulfill this role, a router or multilayer switch must be able to support multiple telecommunications interfaces of the highest speed used in the WAN core. It must also be able to forward IP packets at full speed on all of those interfaces. The router or multilayer switch must also support the routing protocols being used in the core.
PSTN
public switched telephone networ
ISDN
Integrated Services Digital Network
diff. between circuit switching and packet switching
circuit switching: a dedicated connection/ path between two devices is held for all communications (expensive and inefficient).
packet switching: data is encapsulated in packets that can then tracel over any connection to get to the destination and is very efficient. also connections don’t need to be pre-made before sending data.
PSN?
packet switched network
connection less systems?
full addressing info must be carried in each packet.Each switch must evaluate the address to determine where to send the packet. An example of a connection-less system is the Internet.
Connection-oriented systems ?
part of the packet switched network: network predetermines the route for a packet, and each packet only has to carry an identifier. The switch determines the onward route by looking up the identifier in tables held in memory.
(VC)
When the circuit is established temporarily while a packet is traveling through it, and then breaks down again, it is called a virtual circuit
(DLCIs)
An example of a connection-oriented system is Frame Relay. In the case of Frame Relay, the identifiers used are called data-link connection identifiers (DLCIs).
Integrated Services Digital Network (ISDN)
circuit-switching technology that enables the local loop of a PSTN to carry digital signals, resulting in higher capacity switched connections.
Integrated Services Digital Network (ISDN)
circuit-switching technology that enables the local loop of a PSTN to carry digital signals, resulting in higher capacity switched connections. (**ISDN is a telephone line service)
