Lab 5.4.6.3:  Neotrace & traceroute - Overview

Estimated time: 15 min.

• Use the shareware program NeoTrace to verify the network path from source router to destination router with a graphical display. 
• Verify that the network-layer between source, destination and each router along the way is working properly. Retrieve information to evaluate the end-to-end path reliability.
• Determine delays at each point over the path and whether the host can be reached.

In this lab you will use the shareware utility NeoTrace to determine the path that data travels through an Internetwork. In semester 2 you completed a lab using the Cisco IOS traceroute command. NeoTrace uses graphics to depict the results of the traceroute command. Additionally, NeoTrace displays the "Whois" information for each router, by looking up the domain name owner and labeling this information for each router on the data path.

The traceroute command uses ICMP packets and the error message generated by routers when the packet exceeds its Time To Live (TTL). When you initiate the traceroute command to a target host the router sends an ICMP echo-request packet with the TTL set to one (1). The first router in the path to the target host receives the ICMP echo-request packet and sets the TTL to zero (0). The first router then sends an ICMP Time-exceeded message back to the source. The source router then sends an ICMP echo-request packet with the TTL set to two (2). The first router receives the ICMP echo-request and sets the TTL to one (1) and sends it to the next router in the path to the target host. The second router receives the ICMP echo-request and sets the TTL to zero (0) then sends an ICMP Time-exceeded message back to the source. The source then sends an ICMP echo-request with a TTL set to 3. This cycle continues until an ICMP echo-reply is received from the target host or until a ICMP destination-unreachable message is received. This allows you to determine the last router to be reached in the path to the target host. This is a troubleshooting technique called fault isolation.

Tools / Preparation:

Prior to starting the lab you will need a PC workstation with Internet access and NeoTrace installed. You will be able to download an evaluation version of NeoTrace. Please review the license provided with NeoTrace to ensure that you are abiding by the rules of its shareware use. The location of the NeoTrace program can be found below in Web Site Resources.

Resources Required:

• PC with monitor, keyboard, mouse, and power cords etc.
• Windows operating system (Win 95, 98, NT or 2000) installed on PC
• PC with NeoTrace program installed and connected to the lab routers
• PC with NeoTrace program installed and access to the Internet

Web Resources:

Routing basics
General information on routers
2500 series routers
1600 series routers
Terms and acronyms
IP routing protocol IOS command summary
NeoTrace 

Step 1 - Run the NeoTrace program.

Start the NeoTrace program by clicking on the Windows Start button, then Programs. Click the NeoTrace program group and then click the NeoTrace icon. If NeoTrace needs to be installed, download it from the web site listed above.

If this is the first time the program has been run, you will need to fill in the blanks on the Home Location screen. This allows the program to look up the latitude and longitude for your location. Click the "Try NeoTrace" button to continue.

Step 2 - Enter the address of an Internet resource to trace to.

In the address field, type www.cisco.com and press enter. This address of the site you are tracing to could be any IP address or computer that is accessible from your location, either on the Internet or on your private LAN/WAN.

You will notice that as the process of tracing takes place, a series of dots and line segments are displayed. Once the traceroute command is completed, the display shows a map with the approximate locations of the routers between your location and Cisco's web site.

Place the mouse pointer near the green dot near San Jose, California. Clicking the left mouse button will zoom in, and clicking the right mouse button will zoom out. Zoom in until you see the green circular dot with only one line segment connecting to it. Place the mouse pointer on this dot.

1. What information is displayed? (answers may vary) 

Step 3 - Display information on the nodes.

Click on the Nodes tab on the left-hand side of the screen. A block diagram of the path taken to reach Cisco's web site is displayed. You will note that periodically the line segments between each node, or router, turn green. NeoTrace is running the traceroute command again to check the path to your destination, since this path may change. You will notice that the average time (expressed in milliseconds) may change each time the traceroute command is executed. The DNS name of each node is also displayed.

Step 4 - Display List information.

Click on the List tab on the left-hand side of the screen. NeoTrace displays the results of the traceroute command in a manner very similar to that of the Cisco IOS traceroute command. You will note that periodically an arrow shows up on the far left hand side of the list. NeoTrace is running the traceroute command again to check the path to your destination, since this path may change.

Step 5 - Display graph information.

Click on the Graph tab on the left-hand side of the screen. NeoTrace displays the results of the traceroute command as a line graph. This graph shows the current time as a gray line, and the average time as a blue line. The vertical access represents each node or router in the path to your destination. Placing the mouse pointer over any of these nodes displays the "Whois" information found for that particular router. The horizontal access represents the time in milliseconds.