Discovering the route between you and a target

Let’s run through a basic scenario where we discover the route between your computer and an interesting destination (maybe one you're having a problem with).

Normally, when troubleshooting a problem, you want to run PingPlotter against the server where you're experiencing problems. Maybe that's a web server (in which case, you'll want to enter that web server's address); maybe it's a game server (in which case you'll want to enter that game server's address). If you aren’t experiencing problems with your network connection or something you access with it currently, no worries – just think of something you access regularly with your Internet connection to use in the exercise below. If you really can’t think of anything right now, feel free to use something interesting like quikorder.pizzahut.com or bigmac1.mcd.com. It doesn’t have to be food related either... If you don’t like Pizza Hut or McDonalds, and can’t come up with a server off the top of your head, use www.pingplotter.com.

We’re assuming here that you’ve downloaded and installed PingPlotter. If you haven’t, please see the Downloading and Installing PingPlotter section for instructions on how to do so.

So load up PingPlotter, and let’s get started!

1. Enter the IP Address (i.e. 129.41.62.29) or the DNS Name (i.e. www.pingplotter.com) of a destination you may be having problems with, or for now enter one of the sites we mentioned above, into PingPlotter’s Address to Trace: input box. Note we just want the name of the destination. You would not enter http://www.problemserver.com/index.html here. What we want is between the http:// and the /index.html.

For now let’s leave all the other settings you see on the screen as they are.

2. After you’ve typed in the address, either press the Enter key on your keyboard, or press the Trace button in PingPlotter’s lower left corner. The trace then starts, and you’ll see the upper Trace Graph populate with the route information to the target you entered. The Timeline Graph for that target will be displayed also below the Trace Graph.

Before we start looking at the graphs, it’s important to cover the concept of a Sample Set because we’re going to be mentioning it a lot. The sample set is defined by the Samples to include: box above the Trace button (which will actually be a Stop button if your trace is still running). The PL%, and Avg columns in your trace graph are all computed off of this number. If this value is set to 10, PingPlotter uses the last ten samples it’s done and bases everything off that number. If it’s set to 20, PingPlotter uses the last twenty traces it’s done, etc. As we go through what you’re actually seeing on the graphs, just remember that the Sample Set is based off the value in the Samples to include: box, and that number represents the number of samples - starting with the most recent and working backwards.

The Trace Graph

The Trace Graph shows you how many hops there are between you and the destination you entered previously. If this is your first time running PingPlotter, or if you haven’t made any changes to unhide other columns, you will see the following columns (starting from the left):

• Hop - You’ll notice that as you go down the Trace Graph from top to bottom, the Hop number increments. What the Hop number shows you is that, for instance, data from you to the target hits the device at Hop 1 first, and then goes to Hop 2, etc. al. Those hops you see are most likely network routers or servers, but they really could be anything that will forward our Ping requests.
• PL% - The percentage number of data packets that have been lost in the current Sample Set. So if you have your Samples to Include: set to 10, and five of the last ten traces PingPlotter sent to that hop didn’t even make it back to PingPlotter, your PL% for that hop will be 50. So PL%, or packet loss percent, gives you a number at a glance for that hop of how many packets have made it out and should have made it back. Obviously a high packet loss percentage here isn’t a good thing.
• IP - The IP address for that hop.
• DNSName - The DNS name for that hop. If you’re seeing a ------------ instead of a name, PingPlotter wasn’t able to get DNS information for that device.
• Avg - The average response time in milliseconds for the number of samples in that Sample Set.
• Cur - The Cur column shows you the roundtrip time (the Ping time) in milliseconds for data to make it to that hop and back again. Another term for this roundtrip time is latency.

So what does your Trace Graph look like? How many hops are between you and the site or server you’re tracing to?

One thing that is kind of an “ah ha!” moment for a lot of first time PingPlotter users is seeing that you really do have that many devices your network traffic passes through to get to web sites, servers, etc. If you click on a web page link, that “click” is passed on by all those hops to that final web server/page, that web server executes that click, passes the information back to you through all those hops and you see it on your browser.

The Timeline Graph

The Timeline Graph is the lower scrolling histogram that you see when PingPlotter is running traces. It is a graphical history of every trace returned, or not returned, from the target. The black line shows you the average latency (as mentioned above, the roundtrip time in milliseconds for the final destination), while the red line shows you packet loss.

We’ll cover the Trace and Timeline Graphs in more detail when we delve into problem identification and determination. Everything you ever wanted to know about the graphs in PingPlotter, including the other columns available to you for the Trace Graph, more in depth definitions of everything on it, and more information on the Timeline Graph, is available in the Graphs section of our online Tutorial and Product Manual.

Some things to consider before we move on:

• We cover what's "normal" for latency and packet loss in a knowledge base entry at http://www.nessoft.com/kb/42
• If you get a Destination Address Unreachable for the last hop in the trace graph, this means something between your computer and the final destination isn't receiving and/or returning packets. We cover this in detail in the PingPlotter section of our knowledge base at www.nessoft.com/kb/8. If some hops are responding, you might try using a different target address (i.e.: try www.pingplotter.com instead of the address you entered the first time).
• If the final destination is working (i.e.: the Round Trip row is showing), but some of the earlier hops are not, then don't despair! This could be normal. See knowledge base articles www.nessoft.com/kb/24 and www.nessoft.com/kb/29 for possible causes of this behavior.
• If you're entering an IP address and would like to "label" that address, or give it a "friendly name" to make it easier to find in history later, you can do that by entering the IP Address, then a space, and then the label. For instance, if you have a core router that you'd like to see displayed in PingPlotter as "Core Router" (minus the quotes), you'd enter it as "192.168.0.1 Core router", omitting the quotes and substituting the 192.168.0.1 for the IP Address for the actual IP Address for your router. For more details on this, see http://www.nessoft.com/kb/23.