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Manual Chapter: BIG-IP Local Traffic Manager version 9.3 Implementations: 17 -Using Link Aggregation with Tagged VLANs
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17

Using Link Aggregation with Tagged VLANs


Introducing link aggregation with tagged VLAN interfaces

You can use the BIG-IP® system in an aggregated two-interface load balancing topology. Link aggregation is the process of combining multiple links so that the links function as a single link with higher bandwidth. Link aggregation occurs when you create a trunk. A trunk is a combination of two or more interfaces and cables configured as one link.

The examples in this chapter show a trunk that includes two tagged interfaces aggregated together. A tagged interface is an interface that is configured to process traffic for multiple VLANs. A VLAN tag identifies the specific VLAN, and allows traffic to be passed through that specific VLAN. In order to cause traffic for multiple VLANs to be passed through a single trunk, you must assign the same trunk to each VLAN.

In the examples, we create a trunk (trunk1) that includes two interfaces, 1.1 and 1.2, and then assign trunk1 as a tagged interface to both VLAN external and VLAN internal. Consequently, inbound and outbound traffic passing between the BIG-IP system and the vendor switch can use either interface. For example, traffic destined for VLAN external can pass through either interface, 1.1 or 1.2.

Aggregating the two interfaces into a trunk to create a link has the following advantages:

  • It increases the bandwidth of the individual network interface cards (NICs) in an additive manner.
  • If one link goes down, the other link can handle the traffic by itself.

The examples in this chapter show you how to use link aggregation in two configurations, a two-network configuration and a single-network configuration.

Using the two-network aggregated tagged interface topology

Figure 17.1 shows a two-IP network topology, with one network connected to VLAN external, and a separate network connected to VLAN internal.

 

Figure 17.1 An example of an aggregated two-interface load balancing configuration

To configure the BIG-IP system for the two-network solution, you must complete the following tasks:

  • Create a trunk to aggregate the links.
  • Assign the trunk as a tagged interface to VLAN internal and VLAN external.
  • Create a pool of web servers that you want to load balance.
  • Create a virtual server that load balances the web servers.
Note

This example assumes that you are using the default internal and external VLAN configuration. It also assumes that the self IP addresses on each VLAN are on the same IP networks as the BIG-IP system.

Aggregating the links

The first task for this solution is to aggregate the links. To do this, you must create a trunk, assign interfaces to the trunk as members, and then enable Link Aggregation Control Protocol (LACP).

To aggregate links

  1. On the Main tab of the navigation pane, expand Network, and click Trunks.
    The Trunks screen opens.
  2. On the upper-right corner of the screen, click Create.
    The New Trunk screen opens.
  3. Note: If the Create button is unavailable, this indicates that your user role does not grant you permission to create a trunk. Users assigned either the Administrator or Resource Administrator role can create a trunk.
  4. In the Name box, type a name for the trunk, such as trunk1.
  5. For the Interfaces setting, locate the Available box and select an interface.
  6. Note: The lowest-numbered interface is the controlling, or reference, interface.
  7. Using the Move button, move the interface number to the Members box.
  8. Repeat step 5 for all interfaces that you want to include as trunk members.
  9. For the LACP setting, check the box.
    This enables dynamic link aggregation.
  10. Click Finished.

Assigning a trunk to the VLANs

After you aggregate the links, you assign the trunk to the VLAN as a tagged interface.

Warning

You must perform this task from the management interface; otherwise you will be disconnected from the BIG-IP system.

To add tagged interfaces to an existing VLAN

  1. On the Main tab of the navigation pane, expand Network, and click VLANs.
    The VLAN screen opens.
  2. In the Name column, click the VLAN name internal.
    This displays the properties of that VLAN.
  3. For the Interfaces setting, locate the Available box and select the name of the trunk that you created in the previous procedure.
  4. Click the Move button to move the trunk name to the Tagged box.
    This assigns the trunk to the VLAN, as a tagged interface.
  5. Click Update.
  6. Return to the list of existing VLANs.
  7. Repeat steps 2 - 5 for VLAN external.
  8. Click Update.

Creating a pool of web servers to load balance

After you create the network environment for the BIG-IP system, you can create the pool of web servers you want to load balance.

To create a pool

  1. On the Main tab of the navigation pane, expand Local Traffic, and click Pools.
    The Pools screen opens.
  2. In the upper-right corner of the screen, click Create.
    The New Pool screen opens.
  3. In the Name box, type a name for the pool, such as myweb_pool.
  4. For the New Members setting, add the pool members:
    1. Click the New Address option.
    2. In the Address box, type the IP address of a web server in the pool.
    3. From the Service Port list, select a service.
    4. Click Add.
    5. Repeat steps b, c, and d for each server in the pool.
  5. Click Finished.

Creating a virtual server to load balance the web servers

After you create the pool of web servers you want to load balance, you can create the virtual server.

To create a virtual server

  1. On the Main tab of the navigation pane, expand Local Traffic, and click Virtual Servers.
    The Virtual Servers screen opens.
  2. In the upper-right corner of the screen, click Create.
    The New Virtual Server screen opens.
  3. In the Name box, type a name for the virtual server, such as vs_myweb.
  4. In the Destination box, verify that the type of virtual server is Host, and in the Address box, type an IP address for the virtual server. Using the example in Figure 17.1 , this address could be 10.0.10.30.
  5. In the Resources area of the screen, locate the Default Pool setting and select the name of the pool you created in the previous section (for example, myweb_pool).
  6. From the Default Persistence Profile setting, select source_addr.
    This implements simple persistence, using the default source address affinity profile.
  7. Click Finished.

Using the one-network aggregated tagged interface topology

Figure 17.2 shows a single IP network topology. The one-network topology is identical to the two-network topology in all respects except that in the one-network solution, VLAN internal and VLAN external connect to members of the same IP network. This requires that the two VLANs be grouped in order to be able to exchange packets directly.

 

Figure 17.2 An example of an aggregated two-interface load balancing configuration with one IP network

You configure the one-network topology in exactly the same way as the two-network topology (allowing for the fact that the virtual server address will now belong to the same network as the servers), with one additional step: the internal and external VLANs need to be grouped. Therefore, to configure the BIG-IP system for this solution, you must complete the following tasks:

  • Configure the tagged interfaces, load balancing pool, virtual server, and trunk exactly as in the two-network configuration.
    For more information, see Using the two-network aggregated tagged interface topology .
  • Remove the self IP addresses from the internal and external VLANs.
  • Combine the internal and external VLANs into a VLAN group.
  • Assign a self IP address to the VLAN group.

Removing the self IP addresses from the VLANs

Before you can create a VLAN group, you must remove the self IP addresses from the individual VLANs. After you create the VLAN group, you create a self IP address for the VLAN group, for routing purposes. The individual VLANs no longer need their own self IP addresses.

Warning

You must perform this task from the management interface; otherwise you will be disconnected from the BIG-IP system.

To remove the self IP addresses from the default VLANs

  1. On the Main tab of the navigation pane, expand Network, and click Self IPs.
    The Self IPs screen opens.
  2. Using the IP Address and VLANs columns, locate the self IP addresses for the internal and external VLANs.
  3. To the left of each self IP address you want to delete, check the Select box.
  4. Click Delete.
    A confirmation screen appears.
  5. Click Delete again.

Creating a VLAN group

Create a VLAN group that includes the internal and external VLANs. Packets received by a VLAN in the VLAN group are copied onto the other VLAN. This allows traffic to pass through the BIG-IP system on the same IP network.

Tip


A VLAN group name can be used anywhere that a VLAN name can be used.

To create a VLAN group

  1. On the Main tab of the navigation pane, expand Network, and click VLANs.
    The VLANs screen opens.
  2. From the VLAN Groups menu, choose List.
    This opens the VLAN Groups screen.
  3. Note: If the Create button is unavailable, this indicates that your user role does not grant you permission to create a VLAN group. Users assigned either the Administrator or Resource Administrator role can create a VLAN group.
  4. In the upper-right corner of the screen, click Create.
    This opens the New VLAN Group screen.
  5. In the Name box, type the name myvlangroup.
  6. For the VLANs setting, use the Move button to move the internal and external VLAN names from the Available box to the Members box.
  7. Click Finished.

Creating a self IP for the VLAN group

After you have created the VLAN group, create a self IP address for the VLAN group. The self IP address for the VLAN group provides a route for packets destined for the network. With the BIG-IP system, the path to an IP network is a VLAN. However, with the VLAN group feature used in this example, the path to the IP network 10.0.0.0 is actually through more than one VLAN. Since IP routers are designed to have only one physical route to a network, a routing conflict can occur. The self IP address feature on the BIG-IP system allows you to resolve the routing conflict by putting a self IP address on the VLAN group.

To create a self IP address for a VLAN group

  1. On the Main tab of the navigation pane, expand Network, and click Self IPs.
    The Self IPs screen opens.
  2. In the upper-right corner of the screen, click Create.
  3. In the IP Address box, type a self IP address for the VLAN group.
  4. In the Netmask box, type a netmask for the self IP address.
  5. For the VLAN setting, select the name myvlangroup from the list.
  6. Click Finished.



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