| A | B |
|---|
| What OSI layer does a WAN operate at? | physical layer and the data link layer |
| What 3 things are WANS designed to do? | operate over a large geographic area, allow access over serial interfaces operating at lower speeds, provide full and part-time connectivity |
| 4 WAN devices | Routers, switches, modems, communication servers |
| Who usually provides the WAN physical layer protocols? | WAN service providers such as RBOCs, alternate carriers, post-telephone, and telegraph (PTT) agencies |
| What do WAN Layer 2 protocols describe? | how frames are carried between systems on a single data link. |
| Who is typically the DCE? | Service provider |
| What is typically the DTE? | the attached device |
| 4 Data Link Layer WAN protocols | HDLC, Frame Relay, Point to Point, ISDN |
| Data Link Layer WAN protocol that does NOT perform error correction | Frame Relay |
| What popular protocol is used for carrying ip packets? | SLIP |
| the maximum bandwidth rate for BRI ISDN? | 128 kbps |
| packet-switched technology has extensive error-checking capabilities | X.25 |
| What size frames does ATM use to carry data? | fixed length (53 byte) frames |
| How does a T1 line assign time slots for data transmission? | they use time division multiplexing to "slice up" and assign time slots for data transmission |
| What’s the bandwidth of a T1 line? | 1.544 Mbps |
| What’s the bandwidth of a E1 line? | 2.048 Mbps |
| Who was xDSL designed for? | The home user |
| What causes bandwidth to decrease in a xDSL line? | bandwidth which decreases with increasing distance from the phone companies equipment |
| What’s a common bandwidth speed for an xDSL line? | from 100s of kbps to several Mbps |
| What type of media was SONET designed for? | designed for optical fiber |
| How does SONET achieve high data rates? | wavelength division multiplexing (WDM), in which lasers are tuned to slightly different colors (wavelengths) in order to send huge amounts of data optically |
| What’s the typical speed of a dial-up modem? | 56 kbps |
| What is the medium in a wireless connection? | electromagnetic waves |
| four basic components of a router and a computer | a CPU, memory, interfaces, and a bus |
| What software does a router need to run configuration files? | Internetworking Operating Software (IOS) |
| What 2 decisions does a router make? | Selects best path for packets |
| Where are routing tables stored? | RAM/DRAM |
| Where are packets held until they are sent out? | RAM/DRAM |
| Where are a router’s startup config files stored? | NVRAM |
| Where is the router operating system image stored? | FLASH |
| Where are the router's power-on diagnostics stored? | ROM |
| What is a network connection where packets enter and exit called? | Interface |
| What two things are routers used for? | Segment LANS & WAN devices |
| What device is the backbone of the internet? | Router |
| What layer of the OSI model does a router operate at? | Layer 3 |
| How does a router make decisions? | network addresses (on the Internet, by using the Internet Protocol, or IP) |
| How do routers select the best patch and switch packets | by building routing tables and exchanging the network information contained within them with other routers |
| How do routers learn information about other routers? | Exchange routing tables |
| What four types of routers are used on the Internet? | Internal routers, Area border routers, Backbone routers, Autonomous system routers |
| What 5 things must an internetwork include? | consistent end-to-end addressing, addresses that represent network topologies, best path selection, dynamic routing, switching |
| What protocol is almost universally routed over the Internet? | IP |
| What routing protocol is widely used over the internet? | Border Gateway Protocol (BGP) |
