# Add system communication interfaces for Layer 2 Engines

Normal Interfaces are used for communication between the Layer 2 Engine and the Management Server.

##

A Physical Interface element corresponds to a network port on the Layer 2 Engine. By default, the numbering of the Physical Interfaces in the SMC Client corresponds to the operating system interface numbering on the engine. For example, Interface ID 0 is mapped to eth0, and Interface ID 1 is mapped to eth1. However, the mapping is not fixed and you can change it through the engine command line.

In a Single Layer 2 Engine, Normal Interfaces are used for the following types of communication:

- Communication between the Layer 2 Engine and the Management Server.
- For sending event information and traffic recordings to Log Servers.

In a Layer 2 Engine Cluster, Normal Interfaces handle all traffic for which the endpoint of the communication is a node itself. Normal Interfaces are used for the following types of communication:

- The Heartbeat communication between the nodes.
- Communication between each individual node and the Management Server.
- For sending event information and traffic recordings to Log Servers.
- For any other traffic between the node itself and some other host.

Each Layer 2 Engine needs at least one interface for communicating with other SMC components. You can define more than one system communication interface if it is necessary in your network environment. Multiple Normal Interfaces can be configured for the same physical network interface. It is recommended to create a separate Normal Interface for each of the following uses:

- For communication with the Management Server.
- For sending event information and traffic recordings to Log Servers.

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

## Steps

1. Right-click a Single Layer 2 Engine or Layer 2 Engine Cluster and select Edit <element type>.
   The Engine Editor opens.
2. In the navigation pane on the left, select Interfaces.
3. In the Interfaces pane on the right, right-click the empty space and select New Physical Interface.
4. Define the Physical Interface properties.
   Select Normal Interface as the Type.
   CAUTION:
   Make sure that you set the Interface speed correctly if you enter a Throughput value for QoS. When the bandwidth is set, the Layer 2 Engine 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.
5. Click OK. The Physical Interface is added to the interface list.
6. Continue the configuration in one of the following ways:
   - If the system communications must use a particular VLAN on the directly connected network segment, add VLAN interfaces.
   - Otherwise, add IP addresses to the system communication interfaces.

## Physical Interface Properties dialog box (Layer 2 Engine)

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

Note: The available options can vary depending on the type of Layer 2 Engine.

Option | Definition
--- | ---
General tab
Interface ID | The Interface ID automatically maps to a physical network port of the same number during the initial configuration of the engine. The mapping can be changed as necessary through the engine’s command line interface. Note: Changes to the Master Engine interface mapping do not affect the Interface IDs that are defined for Virtual Engines in Virtual Resource elements.
Type | Normal interface — Corresponds to a single network interface on the Layer 2 Engine. Capture Interface — Traffic is only captured for inspection. Note: Capture Interfaces allow the hosted Virtual Layer 2 Engine to listen to traffic that is not routed through the Master Engine. You can have as many Capture Interfaces as there are available physical ports on the Master Engine. External equipment must be set up to mirror traffic to the Capture Interface. Inline Interface — The interface is directly on the traffic path so that traffic must always pass through the Layer 2 Engine to reach its destination. Only traffic that attempts to pass through Inline Interfaces can be actively filtered. Note: An Inline Interface consists of two different Physical Interfaces on the Master Engine. This way, the hosted Virtual Layer 2 Engine can inspect the traffic coming from one interface and either stop the traffic or send it out through the other interface.
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.

Option | Definition
--- | ---
Inline Interface Settings or Capture Interface Settings section
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.
Inspect unspecified VLANs | (When Type is Capture Interface or Inline Interface) Deselect this option to make the Security Engine ignore traffic from VLANs that are not included in the Security Engine's interface configuration. We recommend that you keep this option selected if you do not have a specific reason to deselect it.
Inspect QinQ | Select this option to make the engine inspect double-tagged VLAN traffic as defined in IEEE 802.1Q. We recommend that you keep this option selected if you do not have a specific reason to deselect it.
Bypass unspecified VLANs (Master Engines only) | (When Type is Inline Interface) When this option is selected, traffic from VLANs that are not allocated to any Virtual Engine is bypassed without inspection. Deselect this option to make the Master Engine block traffic from VLANs that are not allocated to any Virtual Engine. We recommend that you keep this option selected if you do not have a specific reason to deselect it.

Option | Definition
--- | ---
Second Interface section (Inline Interfaces only)
ID | Select a Second Interface ID. The Interface ID is mapped to a physical network port of the same number during the initial configuration of the engine. Note: Select the Second Interface ID of the Inline Interface in the Virtual Layer 2 Engine that is associated with this interface.
Zone (Optional) | Select the network zone to which the interface belongs. Click Select to select an element, or click New to create an element.
Second Interface ID (Master Engines only) | (When Type is Inline Interface) Select a Second Interface ID. The Interface ID is mapped to a physical network port of the same number during the initial configuration of the engine.

Option | Definition
--- | ---
QoS Mode (Optional) | Select the QoS mode to apply to the link on this interface. You can select from one of the following options: No QoS: When selected, no QoS mode is enabled. QoS Statistics Only: It allows the collection of QoS Class-based counters without activating any other QoS feature. DSCP Handling and Throttling: When selected, no queues and no throttling of all traffic. Only the connections that are tagged with QoS Class are treated as per the action that is defined in the QoS policy. Full QoS: It throttles all traffic to the Interface Throughput Limit that is set in the interface properties Note: 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
--- | ---
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 element to add the Virtual Engine to the Master Engine. Only one Virtual Resource can be selected for each Physical Interface. If you want to add multiple Virtual Resources, add VLAN Interfaces to the Physical Interface, then select the Virtual Resource in the VLAN Interface properties.
Allow VLAN Definition in Virtual Engine | When selected, allows VLAN Interfaces to be added to the automatically created Physical Interfaces in the Virtual Engine that is associated with this interface.
Virtual Engine Interface ID | Specifies the Interface ID of the Physical Interface in the Virtual Engine that is associated with this interface.

Option | Definition
--- | ---
Advanced tab (All optional settings) Note: These options cannot be selected if using Capture Interfaces.
Override Engine's Default Settings | When selected, the default settings of the Security Engine are overridden.
SYN Rate Limits | Default — The interface uses the SYN rate limits defined for the Security 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 Security 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.