Step-By-Step Guide to the CCNA Exam, Part II
Need help studying for Cisco's CCNA exam? In this two-part series, our expert guides you through the CCNA exam objectives.
by Emmett Dulaney
11/6/2002 -- One of the most popular exams currently on the market is the Cisco Certified Network Associate exam (640-607), which leads to CCNA certification. This is a single exam certification, which also acts as a first step toward higher-level Cisco certifications such as CCNP.
In the previous article (click here for Part I) we looked at the first four of the eight objective categories on this exam. This time, the focus will be on the last four major objective categories:
- WAN Protocols
- Network Management
- LAN Design
- Cisco Basics, IOS & Network Basics
The complete list of objectives for this exam from Cisco can be found here.
Objective #5: WAN Protocols
| Sub-Objectives |
Information |
| Recognize key Frame Relay terms and features |
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.
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| List commands to configure Frame Relay LMIs, maps, and subinterfaces |
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.
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| List commands to monitor Frame Relay operation in the router |
Once Frame Relay is up and running, the next phase becomes monitoring the information and statistics it produces. Most of the commands begin with "show" and are run in EXEC mode to see the various statistics. A complete list of the monitoring commands can be found here. |
| State a relevant use and context for ISDN networking |
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.
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| Identify ISDN protocols, function groups, reference points, and channels |
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).
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| Identify PPP operations to encapsulate WAN data on Cisco routers |
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.
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Objective #6: Network Management
| Sub-Objectives |
Information |
| Configure standard access lists to figure IP traffic |
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.
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| Configure extended access lists to filter IP traffic |
See directly above
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| Monitor and verify selected access list operations on the router |
Standard IP Access List Logging is addressed here. You should also read the troubleshooting for dial interfaces found here. |
Objective #7: LAN Design
| Sub-Objectives |
Information |
| Describe full- and half-duplex Ethernet operations |
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.
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| Describe network congestion problem in Ethernet networks |
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.
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| Describe the features and benefits of Fast Ethernet |
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.
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| Describe the guidelines and distance limitations of Fast Ethernet |
Cabling and maximum distance parameters, as well as comparisons to other high-speed LAN technologies can be found here. |
Objective #8: Cisco Basics, IOS & Network Basics
| Sub-Objectives |
Information |
| Examine router elements |
"Feature-by-Feature Router Configurations" are extolled upon here.
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| Manage configuration files from the privilege EXEC mode |
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 "#."
|
| Control router passwords, identification, and banner |
"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.
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| Identify the main Cisco IOS software commands for router startup |
An excellent listing of Cisco IOS Basic Skills – including configuring the router from a PC – can be found here. |
| Log in to a router in both user and privilege modes |
See second sub-objective above. |
Observations
The vast majority of information required in the first set of objectives (Part I) was fairly vendor-neutral. With this set of objectives, the information you need to know becomes more Cisco-specific as you move your way down the list. Study the information found in both of these articles and the provided links, and you'll have a solid background in the information you need to know to pass the CCNA exam. Good luck on your exam! 
Emmett Dulaney is the author of several books on Linux, Unix and certification. He is a former partner in Mercury Technical Solutions and can be reached at .
More articles by Emmett Dulaney:
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