Frame Relay is a packet-switching protocol that was initially created to use over ISDN interfaces for high bandwidth networking. The header for Frame Relay uses a data link connection identifier (DLCI) to pass information on a hop-by-hop basis, minimizing the processing done on each frame (thus allowing for faster transfers). TIP: Whenever thinking of Frame Relay, always think of "fast."

A wonderful 86-page booklet, "The Basic Guide to Frame Relay Networking," published by the Frame Relay Forum can be found here (PDF format). After reading this, read Cisco’s take on the technology and enhancements to it here.

The LMI (Local Management Interface) is Cisco’s set of enhancements to the basic Frame Relay specification. The most common commands to know when discussing Frame Relay are:

show frame-relay PVC

show frame-relay map

The first command shows the status of the PVC (permanent virtual circuit), while the second will show if a remote IP address has been resolved to a DLCI. A complete list of commands for configuring and troubleshooting frame relay can be found here. This document also contains the information on the multipoint subinterfaces and maps.

ISDN (Integrated Services Digital Network) is a relevant technology to use anytime you need to employ voice/video/data over telephone wires. This is typically done in the creation of a WAN and can employ either BRI (Basic Rate) or PRI (Primary Rate) ISDN, with the primary (there are others) difference between the two being the speed; BRI can operate up to 192 kbps, while PRI can reach 2.048 Mbps.

Cisco’s overview of ISDN can be found here. Also pay attention to the sample configuration (and relevant commands) for BRI that can be found here.

ISDN protocols fall into three series: those that start with the letter "E," those that start with the letter "I" and those that start with the letter "Q." Those that start with E all relate to the existing telephone network and ISDN’s use with it. Those that start with I are merely concepts, various aspects (terminology) and interfaces. Those that start with the letter Q are used for switching and signaling.

Functions and references points are things that relate to standards for service providers. Functions are hardware (physical devices such as terminal equipment and terminal adapters) while reference points are interfaces (logical entities). There are four different reference point abbreviations to know:

R – used between a terminal adapter and terminal equipment
S – used between a terminal and a network termination
T – used between two network terminations
U – used between a network terminal and a line terminator

Channels are BRI or PRI (discussed in the previous objective).

PPP (Point-to-Point Protocol) is used for encapsulating and transporting IP data across point-to-point links. As commonsense would dictate, in order to use PPP, it must be available – and in use – on both devices.

HDLC (High-Level Data Link Control) is used within PPP for encapsulating the datagrams. HDLC is an enhancement over SDLC (Synchronous Data Link Control).

Cisco’s overview of PPP can be found here.
A list of the PPP (and SLIP) configuration commands can be found here.

Because of the similarities between the two objectives, both standard and extended access lists (the next sub-objective) are discussed here.

Access lists allow you, the administrator, to limit (restrict) who can access the network and its resources. IP traffic can be filtered (restricted) based on address (source or destination), address range, protocol, precedence, type of service, icmp-related, or state of TCP connection. All standard access list items fall within the range of 1 – 99. Extended access list items fall within the range of 100 – 199.

Lists can be configured with the access-list command and done by using numbers or names. Both methods are described here and here. See also the third sub-objective in this category.

See directly above

Duplexing describes the ability of data to flow in a particular direction. Half duplexing means that data can only flow in one direction at a time (similar to talking over a radio), while full-duplex allows data to go in both directions (send and receive) at the same time. Many ports can be configured to allow for either duplexing mode, though traditional Ethernet operates in half-duplex mode.

At half-duplex mode, collisions can occur and CSMA/CD (Carrier Sense Multiple Access/Collision Detection) is used to respond to them when they happen. In full duplex mode, collisions do not occur.

The more traffic on a traditional network (the more PCs), the more likelihood exists for collisions to occur. Under most situations, CSMA/CD detects the collision and the data is resent after a time delay.

Switches can be used (in place of hubs) to reduce the congestion. With the use of the switch, collisions lose their likelihood of occurring since separate physical networks are essentially replacing the one large network. Running in full duplex, as mentioned in the above objective, eliminates collisions.

Fast Ethernet, also known as 100Base-T (or 802.3u), has several advantages over 10Base-T wit the most obvious being speed. It still uses the existing CSMA/CD protocol and can (if supported) run on the existing wiring – requiring only an upgrade in cards and hubs to increase the speed of an existing network ten fold.

If full-duplex is employed, the speed doubles from 100Mbps to 200Mbps, as transmissions occur in each direction at the same time.

Cisco’s overview of Fast Ethernet can be found here.

"Feature-by-Feature Router Configurations" are extolled upon here.

The difference between "user" EXEC mode and "privileged" EXEC mode is essentially the same as changing from a regular user to a the root user on a Unix/Linux machine. To move to privileged mode, you enter the command enable from the user EXEC session, and successfully doing so is indicated by the prompt changing from ">" to "#."

"Observing System Startup and Performing a Basic Configuration" outlines what you need to know for this objective and can be found here.

Know that there are multiple passwords and commands (enable secret and enable password). Cisco IOS Password facts can be found here.