008 - Networking - C11.1. WAN Concepts / Questions

Which WAN technology can be implemented over regular telephone lines?

Public Switches Telephone Network (PSTN).

What is the optical carrier specification base rate? Why is the base rate significant?

Its 51.84 Mbps. To get other throughput ratings you have to multiply base rate.

Concerning WAN technologies, what is a channel? Why are channels important?

Channels converts signal received from WAN provider into signal that can be used by equipment at the customer's site.

Which WAN technology uses fixed-length cells?

Asynchronous Transfer Mode (ATM) - its a wan communication technology originally designed for carrying time-sensitive data like voice and video. It can also be used for regular data transport.

Which WAN technology is a transport technology for carrying signals over fiber optic cables?

Local loop ?

What are the two parts of a CSU/DSU? Which functions does each perform?

CSU (Channel Service Unit) - Terminates the digital signal and provides error correction and line monitoring. DSU (Data Service Unit) - converts the digital data into synchronous serial data for connection to a router.

What is the difference between a packet-switched network and circuit-switched network?

Circuit Switching - This network uses dedicated connection between sites. Circuit switching is ideal for transmitting data that must arrive quickly in order it is sent, as is the case with real-time audio and video. Packet Switching - Allows data to be broken up into small units called packets. Packets are transmitted along the most efficient route to the destination. Packet switching is ideal for transmitting data that can handle transmission delays, as is often the case with web pages and email. Difference ????????????

How does MPLS add labels to packets? What are these labels used for?

MPLS - is a WAN data classification and data carrying mechanism. It adds label to packets between existing Network and Data Link layer formats. Labels are added when the packet enters MPLS network and are removed when the packet exits the network. Information in label is used to switch the packet through the MPLS network to the destination. They can identify route or even network type to use. MPLS labels are often used to provide different classes of service for data streams

What are the differences between T1 and T3? E1 and E3? J1 and J3?

T1 - 24 channels, run at 64 kbps ea. Coaxial/Twisted pair/ Satellite/Fiber. T3 - 672 channels, run at 64 kbps ea. Fiber optic cable. E1 - 32 channels, run at 64 kbps ea. E3 - 16 E1 signals at the same time. J1 - (Identical to T1) - 24 channels, run at 64 kbps ea. J3 - 480 channels that each run at 64 kbps.