WAN Technologies Comprehensive Study Exam Questions And Answers.

1. WAN - correct answer A wide area network, or WAN, is a network that covers a large geographical area. It may connect multiple smaller networks over metropolitan, regional, and even national boundaries. In a WAN, several switching and transmission technologies are used to transmit data between different network segments. 2. Name 5 main switching technologies that can be used on WAN. - correct answer (1) Circuit Switching (2) Packet Switching (3) Virtual Circuit Switching (4) Cell Switching (5) MPLS 3. Circuit Switching - correct answer In circuit switching, one end point creates a single path connection to another. This is a widely used switching technology. An example of a circuit-switching network is the public switched telephone network, or PSTN. In circuit switching, the word "circuit" refers to the connection path between endpoints. Once a circuit is established, data is transmitted via that path while the circuit is active. Bandwidth is dedicated to the connection until it's not needed anymore. Once the circuit is terminated, bandwidth once again becomes available for use elsewhere on the network. In different sessions, different paths may be used to route data between the same two endpoints. 4. Packet Switching - correct answer In packet-switching networks, data to be transmitted is broken into smaller units known as packets. Each packet takes the best route available at a given time, rather than using a fixed circuit, or path, to the required destination. Each data packet contains all of the routing and sequencing information required to transmit it from one endpoint to another. Once all the packets constituting a message arrive at the required destination, the data they contain is reassembled. Packet switching allows for frequent changes in a network, adjusting the paths that data takes as required to compensate for network congestion or broken links. Frame Relay is an example of a packet-switching standard. It is effective for the on demand nature of traffic which is typical of many networked applications. 5. Virtual Circuit Switching - correct answer Virtual circuit switching has characteristics of both packet and circuit switching. It transfers packets via logical circuits, which don't have physical resources such as frequencies or time slots allocated to them. Frame relay is a packet switching technology which uses virtual circuits. Logical paths are assigned to identities rather than physical locations, and can be either permanent or switched. Each of the packets carries a Virtual Circuit Identifier, or VCI, that is local to a link and updated by each switch on the path, from the source to the destination of the packet. 6. There are 2 types of virtual circuits, what are they? - correct answer • Permanent virtual circuits - or PVCs - which are always on, and • Switched virtual circuits - or SVCs - which make single connections as needed 7. PVC - correct answer A PVC usually takes the form of a leased line, which a customer pays a fixed monthly fee to use. The line is manually built and maintained by a telephone company. A PVC provides a fast, reliable connection that remains fixed - so there's no need for customers to re-establish a connection each time they require one. 8. SVC - correct answer SVCs are set up on a per-call basis. They provide more flexibility than PVCs, enabling a single connection to one endpoint to be connected to multiple other endpoints, as needed. When a network device attempts to connect to a WAN, an SVC is requested and the carrier establishes the connection. Like in the case of long-distance phone calls, customers typically pay for using a connection based on their connection time. This can be less expensive than paying a fixed monthly fee to use a PVC. 9. Cell Switching - correct answer Cell-switching networks are similar to packet-switching networks except that data is transmitted as fixed-length cells instead of as variable-length packets. If there isn't enough data to fill up an entire cell, the rest of the space in the cell is filled with blank - or filler - data. An example of a cell-switching protocol is Asynchronous Transfer Mode, or ATM. The advantage of cell switching over packet switching is its predictability. Cell switching makes it easy to track how much data is moving on a network. 10. MPLS - correct answer MPLS is a high-performance, multi-service, switching technology. It's defined by a set of Internet Engineering Task Force, or IETF, specifications that enable network devices such as routers to establish and manage network traffic. MPLS ensures faster switching of data than normal packet switching because it uses label switching, which can look at Layer 2 attributes to make path determination more efficient. In an MPLS network, a router adds a label to each incoming data packet. Other routers then forward the packet along a predefined path, based on the label rather than on its destination IP address. This reduces the number of routing lookups that routers have to perform. 11. Why is MPLS known as "Multiprotocol"? - correct answer MPLS can transport data using different technologies and protocols such as IP, ATM, Frame Relay, Synchronous Optical Network - or SONET - and Ethernet over a common infrastructure. This is why it's known as "multiprotocol." 12. Explain how MPLS handles network traffic - correct answer MPLS enables class of service, or CoS, tagging and prioritization of network traffic, so network administrators can specify which traffic should take priority on a network, based on which applications are the most important. This makes MPLS especially useful for supporting real-time streaming media applications that are sensitive to transmission delays. For example, it enables administrators to ensure that Voice over IP, or VoIP, traffic is prioritized on a network. MPLS carriers differ in the number of classes of service they offer and the pricing of these CoS tiers. 13. ATM - correct answer ATM is a cell-switching network technology that supports the high-speed transfer of voice, video, and data in LANs, WANs, and telephone networks. ATM WAN implementations are popular because of their versatility and high bandwidth availability. A network using ATM uses switches to transfer information across networks in fixed-size units called cells, consisting of 53 bytes each. ATM is a connection-oriented protocol. In other words, if a node is going to send cells to another node, it will first establish a connection. The connection is terminated once the cells have been sent. 14. Frame Relay - correct answer Frame Relay is a packet-switching protocol that functions at the Physical and Data Link layers of the Open Systems Interconnection model, or OSI model. It enables the transmission of data over a shared network medium using virtual circuits. Virtual circuits consume bandwidth only when they transport data. This maximizes the bandwidth available and allows faster data transfer. Frame Relay provides reliable communication lines and efficient error-handling mechanisms, which discard erroneous data frames. 15. DSL - correct answer Digital subscriber line, or DSL, transmits data, video, and voice over existing phone lines. It transmits voice as low-frequency signals and data as high-frequency signals. DSL is popular for connecting small businesses and households to the Internet because of its affordability, availability, and good download speeds. However, distance from the exchange and the quality of lines affect the total bandwidth available to a customer. 16. ISDN - correct answer ISDN uses PSTN lines to transmit voice and data simultaneously. Unlike telephone signaling, ISDN signals aren't converted to analog - they're transmitted as digital signals. With ISDN, each circuit has a set of identifiers that uniquely identify it. These include a telephone number, a Service Profile Identifier - or SPID - and three dynamic connection identifiers. 17. ISDN is a channelized service and has two interface modes, which are? - correct answer • basic rate interface, or BRI, and • primary rate interface, or PRI, which includes more data channels to provide higher bandwidth 18. T-Carrier System - correct answer The T-carrier system is a digital and packet-switched system designed to carry multiplexed connections. Multiplexing is a cost-saving communication method whereby a single medium is used to transmit multiple digital data streams. It makes communications more scalable. A T-carrier system uses two twisted pairs of copper wires. The first pair is used for transmission, and the second pair is used for reception. As a result, the system supports full-duplex communication. T-carrier systems can be used to support a point-to-point WAN in which the service provider sets up a dedicated connection between two endpoints. T1 and T3 are the two most common T-carrier circuits. 19. Digital Signal (DS) - correct answer Digital Signal, or DS, services are a hierarchy of different digital signals that transfer data at different rates.