Manual Chapter : BIG-IP Link Controller Reference Guide v4.3: Internet Link Evaluator

Applies To:

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Link Controller

  • 4.3 PTF-02, 4.3 PTF-01, 4.3.0
Manual Chapter


4

Internet Link Evaluator



Overview of the Internet Link Evaluator

The Internet Link Evaluator, a statistics screen in the Configuration utility, is a unique tool with which to evaluate the following data about the Internet:

  • The average round trip time between the local DNS servers on a particular continent and the links in your network
  • The average completion rate between the local DNS servers on a particular continent and the links in your network
  • The average number of router hops between the local DNS servers on a particular continent and the links in your network

    The data displayed in the Internet Link Evaluator is based on path data, which is collected when you use a dynamic load balancing mode, such as Round Trip Times or Quality of Service. For more information on dynamic load balancing modes, see Using dynamic load balancing modes, on page 5-4 .

To view the Internet Link Evaluator statistics screen using the Configuration utility

  1. In the navigation pane, expand the Link Statistics item.
  2. Click Link Evaluator.
    The Internet Link Evaluator Statistics screen opens.
  3. For information on working with the Internet Link Evaluator Statistics screen, view the online help.

The round trip time and completion rate data, on the Internet Link Evaluator Statistics screen, are based on path data. The router hops data is based on information collected by the traceroute utility.

Working with the Average Round Trip Time table

In the Average Round Trip Time table on the Internet Link Evaluator Statistics screen, you can view the following information:

  • The average round trip time for each link to each continent
  • For each link, the best average round trip time to the local DNS servers on a particular continent. This value is indicated by bold text within the table.
  • For each continent, the best average round trip time from the links. This value is indicated by underlined text within the table.

    If you hold the mouse pointer over the Information button ( ), you can view the following additional information:

  • For a particular link, the number of local DNS servers used to calculate the average round trip time
  • For all the local DNS servers that have been probed by a particular link, the percentage of those local DNS servers that are located on a particular continent
  • For all the local DNS servers on a particular continent, the percentage of those local DNS servers that have been probed by a particular link

Working with the Average Completion Rate table

In the Average Completion Rate table on the Internet Link Evaluator Statistics screen, you can view the following information:

  • The average completion rate for each link to each continent
  • For each link, the best average completion rate to the local DNS servers on a particular continent. This value is indicated by bold text within the table.
  • For each continent, the best average completion rate from the links. This value is indicated by underlined text within the table.

    If you hold the mouse pointer over the Information button ( ), you can view the following additional information:

  • For a particular link, the number of local DNS servers used to calculate the average completion rate
  • For all the local DNS servers that have been probed by a particular link, the percentage of those local DNS servers that are located on a particular continent
  • For all the local DNS servers on a particular continent, the percentage of those local DNS servers that have been probed by a particular link

Working with the Average Router Hops table

In the Average Router Hops table on the Internet Link Evaluator Statistics screen, you can view the following information:

  • The average number of router hops between each link and each continent
  • For each link, the best average number of router hops to the local DNS servers on a particular continent. This value is indicated by bold text within the table.
  • For each continent, the best average number of router hops from the links. This value is indicated by underlined text within the table.

    If you hold the mouse pointer over the Information button ( ), you can view the following additional information:

  • For a particular link, the number of local DNS servers used to calculate the average number of router hops
  • For all the local DNS servers that have been probed by a particular link, the percentage of those local DNS servers that are located on a particular continent
  • For all the local DNS servers on a particular continent, the percentage of those local DNS servers that have been probed by a particular link

Interpreting the Internet Link Evaluator data

In choosing an ISP provider, enterprises have very few ways to evaluate the quality of the connectivity provided. By measuring the round trip times, completion rate, and average router hops over the configured links on the Link Controller, the Internet Link Evaluator provides a thorough view of link and ISP performance. By comparing link performance over time, you can monitor the actual performance that an ISP delivers to your customers.

The two data points that help you determine which link has the best performance are the RTT response time (lower is better), and the Completion Rate (higher is better). The Round Trip Time measurement calculates the packet speed of a request from each geographically-distributed user. The Completion Rate measurement is an important metric for evaluating the quality of a link, because it represents the percentage of dropped packets. Completion rate is also important for measuring line quality for applications such as streaming media.

Note: One easy way to compare link performance over time is to print a screen shot of the Internet Link Evaluator at a certain time every day.