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Archived Manual Chapter: BIG-IP Reference Guide v4.6.2: Working with Link Configuration
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17

Working with Link Configuration



Overview of link configuration

Link configuration is based on entries you make when you run the Setup utility. When you run the Setup utility, you add the members for the default gateway pool, the self IP addresses for the Link Controller, and the VLANs. These objects are the basic components for link configuration.

You configure the links that you want to load balance in the Configuration utility. When you initially add links, you configure the basic properties for the link. Once you have configured the basic properties, you can refine and enhance the link configuration with several advanced configuration options. This chapter explains how to configure the basic properties of a link, and also how to configure the advanced properties of a link.

Note


For specific examples of how to deploy a link load balancing solution in your network, refer to the Link Controller Solutions Guide .

Defining the basic properties for a link

Before you can load balance inbound and outbound traffic on the Link Controller, you configure the basic links. The following procedure describes how to configure the basic properties of a link.

To configure the basic link properties using the Configuration utility

  1. In the navigation pane, expand the Link Configuration item, and and then click Links.
    The Link List screen opens.
  2. Click the Add button.
    The Link Configuration: Step 1 of 2 screen opens.
  3. In the Link Name box, type a name for the link.
  4. In the Self IP box, select a self IP address to associate with the link.
  5. In the VLAN box, type the name of the VLAN associated with the self IP address you selected in the previous step.
  6. Next to the Gateway IP box, click the Add button to select the gateway IP address to associate with the link.
  7. If you want to limit the volume of inbound traffic, check the box next to Inbound Traffic Limit, and type a number that represents the maximum throughput rate (in kilobits per second) for the inbound traffic on the link. (Note that this is an optional setting.)
  8. If you want to limit the volume of outbound traffic, check the box next to Outbound Traffic Limit, and type a number that represents the maximum throughput rate (in kilobits per second) for the outbound traffic on the link. (Note that this is an optional setting.)
  9. If you want to limit the total volume of bidirectional traffic, check the box next to Total Traffic Limit, and type a number that represents the maximum throughput rate (in kilobits per second) for the sum of inbound and outbound traffic on the link. (Note that this is an optional setting.)
  10. Click Next.
    The Link Configuration: Step 2 of 2 screen opens.
  11. In the Monitor Name box, type a name for the health monitor for the link. Alternately, you can select a default monitor from the list. (Note that this is an optional setting. If you do not want to configure a monitor at this time, skip to step 13.)
  12. In the Monitor Type box, select the type of monitor for the link.
  13. Click Finish.
    The link and optional monitor are added to the configuration, and the Link List screen opens.

Note


For details on any of the settings on the two screens in the Link Configuration wizard, click the Help button.

Working with the advanced properties for a link

Once you have configured the basic link properties, you can configure several advanced properties for the link. The advanced properties include:

  • Additional basic link properties
  • Additional health monitor properties
  • Link weighting and billing properties
  • SNMP properties

Configuring additional basic link properties

Once you have configured the basic properties of a link, you can adjust those properties, and configure several advanced properties. This procedure describes how to configure additional link properties.

To configure additional link properties using the Configuration utility

  1. In the navigation pane, expand the Link Configuration item, and then click Links.
    The Link List screen opens.
  2. Click the name of the link that you want to modify.
    The Link Properties tab opens.
  3. Make any changes that you want to the basic properties of the link. In addition to the properties that you defined when you first configured the link, you can add an ISP name, or redefine the link bandwidth limit settings. For details on the additional settings on this screen, click the Help button.
  4. When you have completed the changes that you want to make, click Apply.

Configuring additional health monitor properties

You can configure a health monitor when you first configure a link, or you can configure a health monitor at a later time. You can also configure additional settings for an existing monitor.

To configure additional health monitor properties using the Configuration utility

  1. In the navigation pane, expand the Link Configuration item, and then click Links.
    The Link List screen opens.
  2. Click the name of the link that you want to modify.
    The Link Properties tab opens.
  3. Click the Link Monitor tab.
    The Monitor screen opens.
  4. On the Monitor screen, you can define a monitor if you did not define one when you first configured the link. You can also configure additional settings for an existing monitor, for example Timeout and Interval. For details on the additional settings on this screen, click the Help button.
  5. When you have completed the changes that you want to make, click Apply.

Note


For additional information about health monitors, see Chapter 12, Monitors .

Configuring link weighting and billing properties

With the link weighting and billing properties, you can refine the link load balancing and statistics reporting for the links in your configuration. On the Link Weighting screen, you determine how the Link Controller manages and distributes traffic across the links, using the following settings.

  • Duplex Billing
    If your ISP provider uses duplex billing, you can set the Duplex Billing option so that the statistics and billing report screens on the Link Controller accurately reflect the bandwidth usage for the link. Note that by default, the duplex billing setting is on.
  • Price Weighting
    If you want the Link Controller to load balance traffic based on the cost of the bandwidth, then select the Use Price Weighting option. You can use this weighting option to avoid the costs associated with exceeding your prepaid bandwidth. You can also use this weighting option to direct traffic over the least expensive link first.
  • Ratio Weighting
    If you want the Link Controller to load balance the total traffic to the controller based on a ratio, then select the Use Ratio Weighting option. When you have links of varying bandwidth sizes, you can use this weighting option to avoid oversaturating a smaller link with too much traffic.

Note


You can use either the price weighting option or the ratio weighting option to load balance your link traffic for all of your links. You cannot use both options. Regardless of which weighting option you use, you must use the same weighting option for all links.

Configuring price weighting for each link

You can set the price weighting that you want the Link Controller to use when load balancing link traffic. The price weighting is based on the billing structure that your ISP uses. The Link Controller load balances traffic to another link if the lowest cost link reaches a threshold that you have set. This helps you control traffic based on the cost the ISP is charging for the bandwidth.

To configure the price weighting for a link

  1. In the navigation pane, expand the Link Configuration item, and then click Links.
    The Link List screen opens.
  2. Click the name of one of the links in the link list.
    The Link Properties screen for that link opens.
  3. Click the Link Weighting tab.
    The Link Weighting screen opens.
  4. Click the Use Price Weighting option.
  5. Next, you configure the following cost elements associated with the link:

    • In the Prepaid Segment box, you can type the maximum bandwidth usage you pay for each month, regardless of how much you use. For example, if your ISP charges $1000 for bandwidth usage in the 0 to 1.54 Mbps range, you would type 1540 in the Prepaid Segment, Up to Kbps box. That means that you pay every month for up to 1.54 Mbps even if you do not use the link at all.
    • In the Incremental Segment box, type the bandwidth (in Kbps) and the associated cost of the next pricing tier. For example, if your ISP charges $2200 for bandwidth usage in the 1.54 to 3 Mbps range, you would type 3000 in the Up to Kbps box and 2200 in the Cost box. Click the Add button (>>) to add the new cost tier to the configuration. You can add additional cost tiers to the configuration if required.
  6. After you complete the configuration, click the Apply button.

Note


If you configure price weighting for one link on the Link Controller, you must configure price weighting for all of the remaining links in the configuration. If you do not, the Link Controller load balances only to the link for which price weighting is defined.

Configuring ratio weighting for each link

Link ratio weighting is based on the bandwidth of the link. The Link Controller load balances traffic to another link if the link reaches a bandwidth usage threshold that you have set. Link ratio weighting is a good option to use if you load balance links of different bandwidths, for example, a T1 link and and a DSL link.

To configure the ratio weighting for a link

  1. In the navigation pane, expand the Link Configuration item, and then click Links.
    The Link List screen opens.
  2. Click the name of one of the links in the link list.
    The Link Properties screen for that link opens.
  3. Click the Link Weighting tab.
    The Link Weighting screen opens.
  4. Click the Use Ratio Weighting option.
  5. In the Link Ratio box, type a number that represents the proportion of total Link Controller traffic that this link should handle in relation to the other links.
  6. Click the Apply button to save your changes.

Additional considerations for link ratio weighting

If you want to load balance link traffic using link ratio weighting, you need to configure the following settings in addition to specifying the ratio weight on the link.

  • Inbound load balancing
    The inbound load balancing mode, on the wide IP, is Quality of Service. All QOS coefficients should be set to 0, except for the Link Capacity coefficient, which should be any number other than 0.
  • Outbound load balancing
    The outbound load balancing mode, for the router pool (usually the default gateway pool), is Dynamic Ratio.

Configuring SNMP properties

If you want the Link Controller to report the metrics gathered directly from the gateway router for the link, you need to enable SNMP for the link. Use the following procedure to enable SNMP communications with the gateway router.

Note


You must also enable SNMP communications on the router itself. Refer to the router manufacturer's documentation for instructions.

To enable SNMP for the gateway router using the Configuration utility

  1. In the navigation pane, expand the Link Configuration item, and then click Links.
    The Link List screen opens.
  2. Click the name of the link that you want to modify.
    The Link Properties tab opens.
  3. Click the Link SNMP tab.
    The SNMP screen opens.
  4. Add the settings to enable SNMP communications for the router. For details on the settings on this screen, click the Help button.
  5. When you have completed the changes that you want to make, click Apply.

Viewing link statistics and metrics

Using the Configuration utility, you can view current statistics about the following objects in the Link Controller configuration:

 

Statistics screen

Description

Summary

Provides information about the Link Controller itself.

Metrics

Provides performance information for the routers, virtual servers, and pools you have configured.

Links

Provides information about the links in the network.

Disabled

Provides information on the links, virtual servers, wide IPs, and pools that are currently disabled.

Requests

Provides information on the virtual connections between local DNS servers and virtual servers for given wide IPs in the network.

Wide IPs

Provides information on the wide IPs, pools, and the virtual servers in the pools.

Virtual servers

Provides information on the virtual servers you have configured.

P95 Billing

Provides information about the average actual link utilization compared to purchased bandwidth.

Link Evaluator

Provides information on the average round trip times, average completion rates, and average router hops between the data centers or links you have configured and local DNS servers.

Paths

Provides information on the paths created by the Link Controller when paths are required to fulfill name resolution requests.

Local DNS

Provides information on the local DNS servers in the Link Controller database.

Config Checker

Provides information about your link configuration. When you are setting up your Link Controller, you can use the Configuration Checker to verify the setup.

 

To view the Link Statistics screens

  1. In the navigation pane, expand the Link Statistics item, and then click the statistics screen that you want to review.
  2. For details on the information provided on each screen, click Help.


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