Cisco’s 8-Step Problem-Solving Model

Cisco General Problem-Solving Model

When troubleshooting a problem a systematic approach works best because the opposite can result in wasted time and resources, and can sometimes make symptoms even worse.

The following is Cisco’s 8 Step Problem-Solving Model:

Step 1:  When analyzing a network problem, make a clear problem statement. You should define the problem in terms of a set of symptoms and potential causes.
To properly analyze the problem, identify the general symptoms and then ascertain what kinds of problems (causes) could result in these symptoms. For example, hosts might not be responding to service requests from clients (a symptom). Possible causes might include a misconfigured host, bad interface cards, or missing router configuration commands.

Step 2:  Gather the facts that you need to help isolate possible causes.
Ask questions of affected users, network administrators, managers, and other key people. Collect information from sources such as network management systems, protocol analyzer traces, output from router diagnostic commands, or software release notes.

Step 3:  Consider possible problems based on the facts that you gathered. Using the facts, you can eliminate some of the potential problems from your list.
Depending on the data, for example, you might be able to eliminate hardware as a problem so that you can focus on software problems. At every opportunity, try to narrow the number of potential problems so that you can create an efficient plan of action.

Step 4:  Create an action plan based on the remaining potential problems. Begin with the most likely problem, and devise a plan in which only one variable is manipulated. Changing only one variable at a time enables you to reproduce a given solution to a specific problem. If you alter more than one variable simultaneously, you might solve the problem, but identifying the specific change that eliminated the symptom becomes far more difficult and will not help you solve the same problem if it occurs in the future.

Step 5:  Implement the action plan, performing each step carefully while testing to see whether the symptom disappears.

Step 6:  Whenever you change a variable, be sure to gather results. Generally, you should use the same method of gathering facts that you used in Step 2 (that is, working with the key people affected, in conjunction with utilizing your diagnostic tools).

Step 7:  Analyze the results to determine whether the problem has been resolved. If it has, then the process is complete.

Step 8:  If the problem has not been resolved, you must create an action plan based on the next most likely problem in your list. Return to Step 4, change one variable at a time, and repeat the process until the problem is solved.



GNS3 – Networking

I finally found time to install and mess with GNS3 and I’m so happy that I did.  Whether you’re studying for certifications or a professional network engineer GNS3 is definitely a must have tool.  GNS3 also has a great community following and here’s an example.  Mark Blackwell posted multiple how-to video’s showing various features of GNS3 and how to configure them in labs.  Features such as Static Routing for Beginners, NAT Port Forwarding, IOS Firewall, Dynamic Access List,  Address Resolution Protocol ARP Concepts with GNS3, and the list goes on.

GNS3 is a Graphical Network Simulator that allows emulation of complex networks.  It allows you to run a Cisco IOS in a virtual environment on your computer. Dynamips is the core program that allows IOS emulation. GNS3 runs on top of Dynamips to create a more user friendly, graphical environment.

GNS3 is an alternative or complementary software tool to using real computer labs for computer network engineers, administrators and people studying for certifications such as Cisco CCNACCNP and CCIE as well as Juniper JNCIA, JNCIS and JNCIE. It can also be used to experiment features or to check configurations that need to be deployed later on real devices. GNS3 also includes other features like connection of the virtual network to real ones or packet captures using Wireshark.



Introduction to GNS3

GNS3 Wikipedia