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Manual Chapter: BIG-IP® version 9.4 Global Traffic Manager and Link Controller Implementations Guide: 10 - Setting Up a Link Controller Redundant System
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10

Setting Up a Link Controller Redundant System


Understanding Link Controller redundant systems

With the Link Controller, you manage incoming and outgoing network traffic, routing that traffic to the appropriate Internet links or destination server. Additionally, you can monitor network resources to determine their availability, and ensure that outgoing traffic is directed to the most efficient and cost-effective link.

A standard implementation of Link Controllers is a high-availability, or redundant, system configuration. A redundant system is a set of two Link Controllers: one operating as the active unit, the other operating as the standby unit. If the active unit goes offline, the standby unit immediately assumes responsibility for managing traffic. The new active unit remains active until another event occurs that would cause the unit to go offline, or you manually reset the status of each unit.

The implementation steps outlined in this chapter describe how to configure a Link Controller redundant system. This example focuses on the fictional company, SiteRequest. The following tables detail the network characteristics at SiteRequest that pertain to this example.

First, the following table outlines the basic characteristics of each Link Controller.

Table 10.1 Link Controller characteristics for the example
Name
Characteristics
lc1.siterequest.com
Self IP address 10.1.1.20 on link1 VLAN
Self IP address 10.1.2.20 on link2 VLAN
Self IP address 172.168.1.20 on internal VLAN
Floating IP address 10.1.1.50 on link1 VLAN
Floating IP address 10.1.2.50 on link2 VLAN
Floating IP address 172.168.1.50 on internal VLAN
lc2.siterequest.com
Self IP address 10.1.1.20 on link1 VLAN
Self IP address 10.1.2.20 on link2 VLAN
Self IP address 172.168.1.20 on internal VLAN
Floating IP address 10.1.1.50 on link1 VLAN
Floating IP address 10.1.2.50 on link2 VLAN
Floating IP address 172.168.1.50 on internal VLAN

Next, the following information applies to the two links that the example network uses.

Table 10.2 Link characteristics for the example
Name
Characteristics
link1
IP address: 10.1.1.5
link2
IP address: 10.1.2.5

In addition, this implementation example includes the following VLANS.

Table 10.3 VLAN characteristics for the example
Name
Characteristics
VLAN 1
Assigned interfaces: 1.1 (untagged)
Role: Communication between network and the first link
VLAN 2
Assigned interfaces: 1.2 (untagged)
Role: Communication between network and the second link
VLAN 3
Assigned interface: 1.3 (untagged)
Role: Communication between Link Controllers and rest of internal network.
Default Gateway
IP address: 10.1.1.100
NTP server
IP address: 192.168.5.15

Last, there are several other network characteristics that play an important role in a redundant system.

Table 10.4 Other system settings for the example
Component
Characteristics
NTP server
IP address: 192.168.5.15
Default Gateway Pool
Name: gw_pool
IP addresses: 10.1.1.5 and 10.1.2.5

For this example, SiteRequest already has both Link Controllers connected to the network, and has access to them through the corresponding management ports.

Setting up a Link Controller redundant system

As detailed in Understanding Link Controller redundant systems , this implementation focuses on the fictional company SiteRequest. This company wants to create a Link Controller redundant system. To use this implementation, you should already have the systems installed on the network; however, you have yet to fully configure them.

The tasks you must complete to create a Link Controller redundant system are:

  • Configure the redundant system settings of each Link Controller
  • Create VLANs
  • Assign self IP addresses to both systems
  • Create a floating IP address that will be shared between the systems
  • Configure the high availability options
  • Define the NTP server
  • Define the default gateway route
  • Define a listener for incoming DNS traffic
  • Run a bigpipe config sync operation
  • Enable synchronization
  • Add links
  • Conduct the initial configuration synchronization between systems through the gtm_add utility

Configuring the redundant system settings

The first step of creating a redundant system with two Link Controllers is to configure the redundant system settings. These settings define each Link Controller as part of a redundant system.

To configure redundant system settings for the active Link Controller

  1. On the Main tab of the navigation pane, expand System and then click Platform.
    The Platform screen opens.
  2. From the High Availability list, select Redundant Pair.
    A new option, Unit ID, displays on the screen.
  3. From the Unit ID list, select 1.
  4. Click the Update button to save your changes.

To configure redundant system settings for the standby Link Controller

  1. On the Main tab of the navigation pane, expand System and then click Platform.
    The Platform screen opens.
  2. From the High Availability list, select Redundant Pair.
    A new option, Unit ID, displays on the screen.
  3. From the Unit ID list, select 2.
  4. Click the Update button to save your changes.

Creating VLANs for Link Controller redundant systems

The next step in this implementation requires you to set up several VLANs. These VLANs encompass the IP addresses associated with the Link Controllers and the other network components that help manage DNS traffic.

For the purposes of this example, you will create three VLANs:

  • link1, which will contain traffic between the Link Controllers and the Link1 router
  • link2, which will contain traffic between the Link Controllers and the Link2 router
  • internal, for communication between the two Link Controllers and the rest of the internal network

You must apply the following procedure to both the active and standby systems.

To create the first VLAN

  1. On the Main tab of the navigation pane, expand Network and then click VLANs.
    The main VLANs screen opens.
  2. Click the Create button.
    The Create VLAN screen opens.
  3. In the Name box, type the name of the first VLAN.
    For this example, type link1.
  4. In the Interfaces option, use the Move buttons to assign the interface 1.1 to the Untagged list.
  5. Click the Finished button to save your changes.

To create the second VLAN

  1. On the Main tab of the navigation pane, expand Network and then click VLANs.
    The main VLANs screen opens.
  2. Click the Create button.
    The Create VLAN screen opens.
  3. In the Name box, type the name of the second VLAN.
    For this example, type link2.
  4. In the Interfaces option, use the Move buttons to assign the interface 1.2 to the Untagged list.
  5. Click the Finished button to save your changes.

To create the internal VLAN

  1. On the Main tab of the navigation pane, expand Network and then click VLANs.
    The main VLANs screen opens.
  2. Click the Create button.
    The Create VLAN screen opens.
  3. In the Name box, type the name of the internal VLAN.
    For this example, type internal.
  4. In the Interfaces option, use the Move buttons to assign the interface 1.3 to the Untagged list.
  5. Click the Finished button to save your changes.

Assigning self IP addresses

With a VLAN in place, you can now assign self IP addresses to each Link Controller. These self IP addresses identify the Link Controller on a per VLAN basis.

For this example, on the link1 VLAN, the Link Controller lc1.siterequest.com uses the self IP address of 10.1.1.20. On the link2 VLAN, the same Link Controller uses the self IP address of 10.1.2.20. Following this pattern, you need to create three self IP addresses for each Link Controller, with each self IP address belonging to either the link1, link2, or internal VLAN.

You must apply the following procedure to both the active and standby systems.

To assign self IP addresses to the first VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the self IP address for the system that applies to the VLAN.
    For this example, type one of the following:
    • If you are configuring lc1.siterequest.com, type 10.1.1.20
    • If you are configuring lc2.siterequest.com, type 10.1.1.21
  4. In the Netmask box, type the subnet mask that applies to this IP address.
    For this example, type 255.255.255.0.
  5. From the VLAN list, select the appropriate VLAN.
    In this example, select link1.
  6. Click the Finished button to save your changes.

To assign self IP addresses to the second VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the self IP address for the system that applies to the VLAN.
    For this example, type one of the following:
    • If you are configuring lc1.siterequest.com, type 10.1.2.20
    • If you are configuring lc2.siterequest.com, type 10.1.2.21
  4. In the Netmask box, type the subnet mask that applies to this IP address.
    For this example, type 255.255.255.0.
  5. From the VLAN list, select the appropriate VLAN.
    In this example, select link2.
  6. Click the Finished button to save your changes.

To assign self IP addresses to the internal VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the self IP address for the system that applies to the VLAN.
    For this example, type one of the following:
    • If you are configuring lc1.siterequest.com, type 172.168.1.20
    • If you are configuring lc2.siterequest.com, type 172.168.1.21
  4. In the Netmask box, type the subnet mask that applies to this IP address.
    For this example, type 255.255.255.0.
  5. From the VLAN list, select the appropriate VLAN.
    In this example, select internal.
  6. Click the Finished button to save your changes.

Creating a floating IP address

In a redundant system, both Link Controllers share common IP addresses called floating IP addresses. To the rest of the network, this floating IP address represents the active Link Controller. If the primary unit goes offline, the secondary unit takes over traffic destined for the floating IP address. This setup ensures that network traffic flows smoothly in the event a fail-over occurs.

Typically, each unit in a redundant system shares a floating IP address for each VLAN on which the redundant system operates. In this example, you need to create three floating IP addresses. These IP addresses represent the two Link Controllers on the link1, link2, and internal VLANs.

For these steps, you need only configure the active system. The settings you establish on this system are transferred to the standby system during a synchronization that you initiate later in this process.

To create a floating IP address for the first VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the floating IP address that is shared between both units.
    In this example, type 10.1.1.50.
  4. In the Netmask box, type the subnet mask that applies to the floating IP address.
    For this example, type 255.255.255.0.
  5. Check the Floating IP option.
  6. Click the Finished button to save your changes.

To create a floating IP address for the second VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the floating IP address that is shared between both units.
    In this example, type 10.1.2.50.
  4. In the Netmask box, type the subnet mask that applies to the floating IP address.
    For this example, type 255.255.255.0.
  5. Check the Floating IP option.
  6. Click the Finished button to save your changes.

To create a floating IP address for the internal VLAN

  1. On the Main tab of the navigation pane, expand Network and then click Self IPs.
    The main self IP address screen opens.
  2. Click the Create button.
    The Create Self IP Addresses screen opens.
  3. In the IP address box, type the floating IP address that is shared between both units.
    For this example, type 172.168.1.50.
  4. In the Netmask box, type the subnet mask that applies to the floating IP address.
    In this example, type 255.255.255.0.
  5. Check the Floating IP option.
  6. Click the Finished button to save your changes.

Configuring the high availability options

Many of the options associated with creating a redundant system reside in the High Availability section of the Configuration utility. These options include the IP addresses of each system, the type of redundant system, and other options.

You must apply the following procedure to both the active and standby systems.

To configure high availability options

  1. On the Main tab of the navigation pane, expand System and then click High Availability.
    The High Availability screen opens.
  2. In the Primary Failover Address option, type the IP address of the active and standby systems.
    For this example, type following:
    • In the Self box, type 172.168.1.20
    • In the Peer box, type 172.168.1.21
  3. Click the Update button to save your changes.
Note

For the standby system, reverse the location of these two IP addresses.

Optionally, you can define a set of secondary failover IP addresses. In this implementation, the secondary failover addresses can be the self IP addresses the Link Controllers use to communicate with link1 or link2.

Defining an NTP server

The next step of this process requires defining an NTP server that both Link Controllers use during synchronization options. This step is important because it determines a common time value for both systems. During file synchronizations, the systems use this time value to see if any newer configuration files exist.

You must apply the following procedure to both the active and standby systems.

To define an NTP server

  1. On the Main tab of the navigation pane, expand System and then click General Properties.
    The general properties screen appears.
  2. From the Device menu, choose NTP.
    The NTP screen appears.
  3. In the Address box, type the IP address of the NTP server you want to use.
    In this example, type 192.168.5.15.
  4. Click the Add button to add the NTP server to your configuration.
    The time server appears as an entry in the Time Server List.
  5. Click the Update button to save your changes.

Defining the default gateway route

Another task you must accomplish is defining the default gateway for network traffic. (In this implementation, the default gateway is a pool containing the IP addresses that correspond to the link1 and link2 links.) Once you create this pool, you can create a default route within the Link Controllers.

You must apply the following procedure to both the active and standby systems.

To create a default gateway pool

  1. On the Main tab of the navigation pane, expand Local Traffic and then click Pools.
    The main pools screen opens.
  2. Click the Create button.
    The New Pool screen opens.
  3. In the Name box, type the name of the default gateway pool.
    For this example, type gw_pool.
  4. In the Health Monitors setting, use the Move buttons to add gateway_icmp to the Active list.
  5. From the Load Balancing Method list, select Dynamic Ratio (node).
  6. In the New Members setting, add the IP address of each link.
    For this example type the following:
    • IP address 10.1.1.5, selecting All Services from the Service Port list. This IP address represents the link1 link.
    • IP Address 10.1.2.5, selecting All Services from the Service Port list. This IP address represents the link2 link.
    Note: You must click the Add button to add the resource to the pool.
  7. Click the Finished button to save your changes.

To define the default route

  1. On the Main tab of the navigation pane, expand Network and then click Routes.
    The main Routes screen opens.
  2. Click the Add button.
    The New Route screen opens.
  3. From the Type list, select Default Gateway.
  4. From the Resource list, select Use Pool and then select the name of the default gateway pool.
    In this example, select gw_pool from the list.
  5. Click the Finished button.

Defining a listener

The Link Controller employs a listener to identify the traffic for which it is responsible. In this implementation, you need to create a listener that corresponds to the floating IP address shared between the two systems.

For these steps, you need only configure the active system. The settings you establish on this system are transferred to the standby system during a synchronization that you initiate later in this process.

To configure the listener

  1. On the Main tab in the navigation pane, expand Global Traffic and then click Listeners.
    The main listeners screen opens.
  2. Click the Create button.
    The new listener screen opens.
  3. In the Destination box, type the IP address on which the system listens for network traffic.
    For this example type 10.1.1.50.
  4. From the VLAN Traffic list, select All VLANs.
  5. Click the Finished button to save the new listener.

Running a config sync operation

For a redundant system, you must employ an additional synchronization option to share the self IP address, default route, and other information you configured on both the active and standby systems.

Note

For the following steps, ensure that you are working with the active Link Controller system.

To run a config sync operation

  1. On the Main tab of the navigation pane, expand System and then click High Availability.
    The High Availability screen opens.
  2. On the menu bar, click Config Sync.
    The Config Sync screen opens.
  3. Click the Synchronize TO Peer button to start the configuration synchronization process.
    The system proceeds to synchronize settings to the standby Link Controller; In this example, lc2.siterequest.com. After the process completes, a screen appears informing you of the settings transferred to the standby unit.
  4. Click the OK button to exit the Config Sync screen.

Enabling synchronization

For the next step, you need to enable the synchronization options and assign an appropriate name for the synchronization group. For this implementation example, the synchronization group name is Link Controller Group A.

For these steps, you need only configure the active system. The settings you establish on this system are transferred to the standby system during a synchronization that you initiate later in this process.

To enable synchronization

  1. On the Main tab of the navigation pane, expand System and then click General Properties.
    The general properties screen opens.
  2. From the Global Traffic menu, choose General.
    The general global properties screen opens.
  3. Check the Synchronization check box.
  4. Check the Synchronize DNS Zone Files check box.
  5. In the Synchronization Group Name box, type the name of the synchronization group.
    In this example, type Link Controller Group A.
  6. Click the Update button to save your changes.

Adding links

The next task you must complete is adding the link objects that represent the two Internet connections. Each Link Controller configuration must contain at least two links for the system to load balance network traffic.

For these steps, you need only configure the active system. The settings you establish on this system are transferred to the standby system during a synchronization that you initiate later in this process.

To add a link

  1. On the Main tab of the navigation pane, expand Link Controller, and then click Links.
    The main link screen opens.
  2. Click the Create button.
    The New Link screen opens.
  3. In the Name box, type the name of the link.
    For this example, type link1.
  4. In the Router Address box, type the IP address of the link.
    In this example, type 10.1.1.5.
  5. In the Health Monitors option, use the Move buttons to add the bigip_link monitor to the Enabled list.
  6. Click the Finish button to save your changes.

You must now repeat the preceding steps to define the second link. In this example, you must define link2 on the Link Controller, using the name link2 and the router address 10.1.2.5.

Running the gtm_add script

Next, you need to have the two units share the same configuration. For this implementation, that means you need to have the standby Link Controller acquire the configurations established at the active Link Controller. You must do this before you attempt to synchronize these systems; otherwise, you run the risk of having the new Link Controller, which is unconfigured, replace the configuration of older systems. To acquire the configuration files, you run the gtm_add script.

Note

You must run the gtm_add script from the currently unconfigured Link Controller.

To run the gtm_add script

  1. Log in to the standby system.
    In this example, log into lc2.siterequest.com.
  2. At the command prompt, type gtm_add.
    A prompt appears, describing what the gtm_add script does and asking if you are sure you want to run the process.
  3. Press the y key to start the gtm_add script.
    The script then prompts you for the IP address of the system from which you want to acquire configuration settings.
  4. Type the IP address of the active system.
    For this example, type 172.168.1.20.
  5. Press Enter.

The gtm_add process begins, acquiring configuration data from the active Link Controller (in this example lc1.sitequrest.com). Once the process completes, you have successfully created a redundant system consisting of two Link Controllers.




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