Add VLAN interfaces for Layer 2 Firewalls

VLANs divide a single physical network link into several virtual links.

VLANs divide a single physical network link into several virtual links. VLANs can be defined for both single and clustered Layer 2 Firewalls. The maximum number of VLANs for a single Physical Interface or Inline Interface is 4094. The VLANs must also be defined in the configuration of the switch or router to which the interface is connected.

Traffic picked up from a VLAN tagged interface can be inspected without configuring VLAN tagging on the Layer 2 Firewall. However, you must configure VLANs on the Layer 2 Firewall if you want to create different traffic inspection rules for different VLANs. Even then, not all VLANs necessarily have to be specified on the Layer 2 Firewall. VLANs can optionally also be used for sending the Layer 2 Firewall’s management and logging connections through a directly connected VLAN segment.

By default, all VLAN traffic is inspected in the same way as non-VLAN traffic. Configure VLAN Interfaces for the physical interfaces if you want to customize traffic inspection for the different VLANs. The traffic inspection is customized for the VLANs by defining different Logical Interfaces for the different VLAN Interfaces. The Logical Interface elements are then used in the Layer 2 Firewall Policy rules to define which rules are used for which VLANs.

If the Layer 2 Firewall encounters unknown VLANs, it might or might not inspect the traffic. The Inspect Unspecified VLANs option in the Inline Interface definitions defines whether the Layer 2 Firewall inspects the traffic. By default, the option is set so that all traffic is inspected.

When you use VLANs with Inline Interfaces, the interface numbers must be different and the VLAN identifier must be identical in both of the Inline Interfaces. For example, 3.101 and 4.101 would be a valid pair of VLAN Inline Interfaces. Also, when a VLAN Interface is used for an Inline Interface, it cannot be simultaneously used for any other types of interfaces.

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Steps

  1. Right-click a Single Layer 2 Firewall or Layer 2 Firewall Cluster and select Edit <element type>.
    The Engine Editor opens.
  2. In the navigation pane on the left, select Interfaces.
    The Interfaces pane opens on the right.
  3. Right-click a Physical Interface and select New > VLAN Interface.
  4. Define the VLAN Interface properties.
    CAUTION:
    The throughput for each VLAN Interface must not be higher than the throughput for the Physical Interface to which the VLAN Interface belongs.
    CAUTION:
    Make sure that you set the interface speed correctly. When the bandwidth is set, the Layer 2 Firewall always scales the total amount of traffic on this interface to the bandwidth you defined. The bandwidth is scaled even if there are no bandwidth limits or guarantees defined for any traffic.
    CAUTION:
    The MTU for each VLAN Interface must not be higher than the MTU for the Physical Interface to which the VLAN Interface belongs.
  5. Click OK.
    The specified VLAN ID is added to the Physical Interface.
  6. Continue the configuration in one of the following ways:
    • If you added a VLAN Interface to a Normal interface, add IP addresses to the VLAN Interface.
    • If you added a VLAN Interface to an Inline Interface, the Inline Interface is ready to use. Click Save and Install to activate the new interface configuration.

VLAN Interface Properties dialog box (Layer 2 Firewall)

Use this dialog box to define the VLAN Interface properties for a Single Layer 2 Firewall, Layer 2 Firewall Cluster, Virtual Layer 2 Firewall, or Master NGFW Engine in the Layer 2 Firewall role.

Note: The available options can vary depending on the type of Layer 2 Firewall and the type of Physical Interface that the VLAN Interface belongs to.
Option Definition
General tab
VLAN ID Enter the VLAN ID (1–4094). The VLAN IDs you add must be the same as the VLAN IDs that are used in the switch at the other end of the VLAN trunk.

Each VLAN Interface is identified as Interface-ID.VLAN-ID, for example, 2.100 for Interface ID 2 and VLAN ID 100.

Second VLAN ID

(Master NGFW Engines only)

Enter the VLAN ID (1–4094) for the Second Interface in the Inline Interface pair. The VLAN IDs you add must be the same as the VLAN IDs that are used in the switch at the other end of the VLAN trunk. Each VLAN Interface is identified as Interface-ID.VLAN-ID, for example, 2.100 for Interface ID 2 and VLAN ID 100.
Note: The VLAN identifier must be identical in both Inline Interfaces. For example, 3.101 and 4.101 would be a valid pair of VLAN Inline Interfaces.
Zone

(Optional)

Select the network zone to which the interface belongs. Click Select to select an element, or click New to create an element.
MTU

(Optional, not supported on Virtual NGFW Engines)

The maximum transmission unit (MTU) size on the connected link. Either enter a value between 400–65535 or select a common MTU value from the list.

If the interface is a Physical Interface, the same MTU is automatically applied to any VLANs created under it.

The default value (also the maximum standard MTU in Ethernet) is 1500. Do not set a value larger than the standard MTU, unless you know that all devices along the communication path support it.

Note: To set the MTU for a Virtual NGFW Engine, you must configure the MTU for the interface on the Master NGFW Engine that hosts the Virtual NGFW Engine, then refresh the policy on the Master NGFW Engine and the Virtual NGFW Engine.
Comment

(Optional)

 A comment for your own reference.
Reset Interface

(Capture Interfaces only)

Select the Reset Interface to specify the interface through which TCP connection resets are sent when Reset responses are used in your IPS policy.
Logical Interface Specifies the Logical Interface. You cannot use the same Logical Interface element for both Inline and Capture Interfaces on the same Virtual IPS engine or Virtual Layer 2 Firewall.
Second Interface

(Optional)

(Inline Interfaces only)

  • VLAN ID — Enter the VLAN ID (1-4094) for the Second Interface in the Inline Interface pair. The VLAN IDs you add must be the same as the VLAN IDs that are used in the switch at the other end of the VLAN trunk. Each VLAN Interface is identified as Interface-ID.VLAN-ID, for example, 2.100 for Interface ID 2 and VLAN ID 100.
    Note: The VLAN identifier must be identical in both Inline Interfaces. For example, 3.101 and 4.101 would be a valid pair of VLAN Inline Interfaces.
  • Zone — Select the network zone to which the Second Interface belongs. To browse for a Zone element, select Select. To create a Zone element, select New.
Option Definition
General tab, Virtual Resource section

(Master NGFW Engines only)

Virtual Resource The Virtual Resource associated with the interface. Select the same Virtual Resource in the properties of the Virtual Firewall element to add the Virtual NGFW Engine to the Master NGFW Engine.
Option Definition
General tab, Quality of Service and Bandwidth Management section
QoS Mode

(Optional)

Defines how QoS is applied to the link on this interface.

If Full QoS or DSCP Handling and Throttling is selected, a QoS policy must also be selected. If Full QoS is selected, the throughput must also be defined.

If the interface is a Physical Interface, the same QoS mode is automatically applied to any VLANs created under it.

QoS Policy

(DSCP Handling and Throttling and Full QoS modes only)

The QoS policy for the link on this interface.

If the interface is a Physical Interface, the same QoS policy is automatically selected for any VLANs created under it.

Note: If a Virtual Resource has a throughput limit defined, the interfaces on the Virtual NGFW Engine that use a QoS policy all use the same policy. The policy used in the first interface is used for all the interfaces.
Interface Throughput Limit

(Full QoS mode only)

Enter the throughput for the link on this interface as megabits per second.

If the interface is a Physical Interface, the same throughput is automatically applied to any VLANs created under it.

The throughput is for uplink speed (outgoing traffic) and typically must correspond to the speed of an Internet link (such as an ADSL line), or the combined speeds of several such links when connected to a single interface.

CAUTION:
Make sure that you set the interface speed correctly. When the bandwidth is set, the NGFW Engine always scales the total amount of traffic on this interface to the bandwidth you defined. This scaling happens even if there are no bandwidth limits or guarantees defined for any traffic.
CAUTION:
The throughput for a Physical Interface for a Virtual NGFW Engine must not be higher than the throughput for the Master NGFW Engine interface that hosts the Virtual NGFW Engine. Contact the administrator of the Master NGFW Engine before changing this setting.
Option Definition
Advanced tab

(All optional settings)

Override Engine's Default Settings When selected, the default settings of the engine are overridden.
SYN Rate Limits
  • Default — The interface uses the SYN rate limits defined for the engine on the Advanced Settings branch of the Engine Editor.
  • None — Disables SYN rate limits on the interface.
  • Automatic — This is the recommended mode if you want to override the general SYN rate limits defined for the engine on the Advanced Settings branch of the Engine Editor. The engine calculates the number of allowed SYN packets per second and the burst size (the number of allowed SYNs before the engine starts limiting the SYN rate) based on the engine’s capacity and memory size.
  • Custom — Enter the values for Allowed SYNs per Second and Burst Size.
Allowed SYNs per Second Defines the number of allowed SYN packets per second.
Burst Size The number of allowed SYNs before the engine starts limiting the SYN rate.
Tip:

We recommend that you set the burst size to be at least one tenth of the Allowed SYNs per Second value. If the burst size is too small, SYN rate limits do not work.

For example, if the value for Allowed SYNs per Second is 10000, set the value for Burst Size to at least 1000.

Enable Log Compression Allows you to define the maximum number of separately logged entries.
For the event type, Antispoofing or Discard, you can define:
  • Log Rate (Entries/s) — The maximum number of entries per second. The default value for antispoofing entries is 100 entries/s. By default, Discard log entries are not compressed.
  • Burst Size (Entries) — The maximum number of matching entries in a single burst. The default value for antispoofing entries is 1000 entries. By default, Discard log entries are not compressed.
Set to Default Returns all changes to the log compression settings to the default settings.