Product Documentation

Allowing L2 Mode on a Citrix ADC instance

In Layer 2 (L2) mode, a Citrix ADC instance acts as a learning bridge and forwards all packets for which it is not the destination. Some features, such as Cloud Bridge, require that L2 mode be enabled on the Citrix ADC instance. With L2 mode enabled, the instance can receive and forward packets for MAC addresses other than its own MAC address. However, if a user wants to enable L2 mode on a Citrix ADC instance running on an Citrix ADC SDX appliance, the administrator must first allow L2 mode on that instance. If you allow L2 mode, you must take precautions to avoid bridging loops.

Precautions:

  1. On a given 1/x interface, untagged packets must be allowed on only one instance. For all other instances enabled on the same interface, you must select Tagged.

    Note:

    Citrix recommends that you select Tagged for all interfaces assigned to instances in L2 mode. Note that if you select tagged, you cannot receive untagged packets on that interface.

    If you have selected Tagged for an interface assigned to an instance, log on to that instance and configure a 802.1q VLAN to receive packets on that interface.

  2. For 1/x and 10/x interfaces that are shared by Citrix ADC instances on which L2 mode is allowed, make sure that the following conditions are met:

    • VLAN filtering is enabled on all the interfaces.
    • Each interface is on a different 802.1q VLAN.
    • Only one instance can receive untagged packets on the interface. If that interface is assigned to other instances, you must select Tagged on that interface for those instances.
  3. If you allow untagged packets for an instance on a 1/x interface, and L2 mode is allowed for that instance, no other instance (with L2 mode allowed or disallowed) can receive untagged packets on that interface.

  4. If you allow untagged packets for an instance on a 1/x interface, and L2 mode is not allowed for that instance, no instance with L2 mode allowed can receive untagged packets on that interface.

  5. If you have provisioned an instance (for example VPX1) in L2 mode on a 0/x interface, and the same interface is also assigned to another instance (for example VPX2), select Tagged for all other interfaces (1/x and 10/x) that are assigned to the second instance (VPX2).

Note: If L2 mode is enabled on a Citrix ADC instance, and both of the management interfaces (0/1 and 0/2) are associated with that instance, only one of the management interfaces can be associated with another Citrix ADC instance on which L2 mode is enabled. You cannot associate both management interfaces with more than one Citrix ADC instance on which L2 mode is enabled.

To allow L2 mode on an instance

  1. In the Provision NetScaler Wizard or the Modify NetScaler Wizard, on the Network Settings page, select Allow L2 Mode. Note: You can activate the Allow L2 Mode setting on an instance when you provision the instance, or while the instance is running.
  2. Follow the instructions in the wizard.
  3. Click Finish, and then click Close.

Allowing L2 Mode on a Citrix ADC instance