Add VLAN Interfaces for IPS engines

VLANs divide one physical network link into several virtual links.

A Virtual Local Area Network (VLAN) is a logical grouping of hosts and network devices that appear as a single network segment regardless of the physical topology. IPS engines support VLAN tagging as defined in the IEEE 802.1q standard. One physical interface can support up to 4094 VLANs.

VLAN tagging can be used:

To inspect VLAN tagged traffic (no VLAN Interface configuration required on the IPS engine).
To define different inspection rules for different VLANs (requires defining VLAN Interfaces for the IPS engine).
For sending the IPS engine’s management and logging connections through a directly connected VLAN segment.

Traffic picked up from a VLAN tagged interface can be inspected without configuring VLAN tagging on the IPS engine. However, you must configure the VLANs on the IPS engine if you want to create different traffic inspection rules for different VLANs. Even then, not all VLANs necessarily have to be specified on the IPS engine. The traffic inspection is customized for the VLANs by defining different Logical Interfaces for the different VLAN Capture Interfaces. The Logical Interface elements are then used in the IPS Policy rules to define which rules are used for which VLANs.

When you use VLAN 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. The VLAN identifiers you configure on the IPS engine must match the switch or router configuration.

When you use VLAN with Capture Interfaces, the network interface used as the Reset Interface for sending TCP Reset responses must be defined in the Capture Interface’s properties. The reset is automatically tagged for the same VLAN that triggers a reset. The Reset Interface must be connected to the same VLAN/Broadcast domain as the Capture Interface to reach the communicating hosts.

If the IPS engine encounters unknown VLANs, it might or might not inspect the traffic. This is controlled by the Inspect Unspecified VLANs option in the Inline and Capture Interface definitions (by default, the option is set so that all traffic is inspected).

CAUTION:

Do not add any manual VLAN definitions to an interface you want to use for sending resets. Adding VLANs prevents selecting the interface as a Reset Interface and also removes the Reset Interface from any existing selections. The IPS engine automatically uses the correct VLAN when sending resets.

For more details about the product and how to configure features, click Help or press F1.

Steps

Right-click a Single IPS or IPS Cluster and select Edit <element type>.
In the navigation pane on the left, select Interfaces.
Right-click a Physical Interface and select New > VLAN Interface.
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 IPS 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 MTU for each VLAN Interface must not be higher than the MTU for the Physical Interface to which the VLAN Interface belongs.
Click OK.
Click Save and Refresh.

Result

The VLAN Interface is now ready. The VLAN Interface is identified as Interface-ID.VLAN-ID, for example 2.100 for Interface ID 2 and VLAN ID 100.

VLAN Interface Properties dialog box (IPS engine)

Use this dialog box to define the VLAN Interface properties for a Single IPS engine, IPS Cluster, Virtual IPS engine, or Master Engine in the IPS role.

Note: The available options can vary depending on the type of IPS engine 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	(When Type is Inline Interface) 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)	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. To set the MTU for a Virtual Engine, you must configure the MTU for the interface on the Master Engine that hosts the Virtual Engine, then refresh the policy on the Master Engine and the Virtual Engine.
Comment (Optional)	A comment for your own reference.
Reset Interface	(When Type is Capture Interface) Select the Reset Interface to specify the interface through which TCP connection resets are sent when Reset responses are used in your 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 Engine.
Second Interface (Optional)	(When Type is Inline Interface) 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
Virtual Resource section (Master Engines only)
Virtual Resource	The Virtual Resource associated with the interface. Select the same Virtual Resource in the properties of the Virtual Engine to add the Virtual Engine to the Master Engine.

Option	Definition
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	(When QoS Mode is Full QoS or DSCP Handling and Throttling) 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 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	(When QoS Mode is Full QoS) 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 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 Engine must not be higher than the throughput for the Master Engine interface that hosts the Virtual Engine. Contact the administrator of the Master Engine before changing this setting.

Option

Definition

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

(When QoS Mode is Full QoS or DSCP Handling and Throttling)

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 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

(When QoS Mode is Full QoS)

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 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 Engine must not be higher than the throughput for the Master Engine interface that hosts the Virtual Engine. Contact the administrator of the Master 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 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. 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	By default, each generated Antispoofing and Discard log entry is logged separately and displayed as a separate entry in the Logs view. Log Compression settings allow you to define the maximum number of separately logged entries. When the defined limit is reached, a single antispoofing log entry or Discard log entry is logged. The single entry contains information about the total number of the generated Antispoofing log entries or Discard log entries. After this log entry, the logging returns to normal and all generated entries are once more logged and displayed separately. Log Compression is useful when the routing configuration generates a large volume of antispoofing logs or the number of Discard logs becomes high. For each 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.