Interfaces

A key task of the BIG-IP^® system configuration is the configuration of BIG-IP system interfaces. The interfaces on a BIG-IP system are the physical ports that you use to connect the BIG-IP system to other devices on the network. These other devices can be next-hop routers, Layer 2 devices, destination servers, and so on. Through its interfaces, the BIG-IP system can forward traffic to or from other network devices.

Every BIG-IP system includes multiple interfaces. The exact number of interfaces that you have on the BIG-IP system depends on the platform type.

A BIG-IP system has two types of interfaces:

A management interface

The management interface is a special interface dedicated to performing a specific set of system management functions.

TMM switch interfaces

TMM switch interfaces are those interfaces that the BIG-IP system uses to send or receive application traffic, that is, traffic slated for application delivery.

Each of the interfaces on the BIG-IP system has unique properties, such as the MAC address, media speed, duplex mode, and support for Link Layer Discovery Protocol (LLDP).

In addition to configuring interface properties, you can implement a feature known as interface mirroring, which you can use to duplicate traffic from one or more interfaces to another. You can also view statistics about the traffic on each interface.

Once you have configured the properties of each interface, you can configure several other features of the BIG-IP system that control the way that interfaces operate. For example, by creating a virtual local area network (VLAN) and assigning interfaces to it, the BIG-IP system can insert a VLAN ID, or tag, into frames passing through those interfaces. In this way, a single interface can forward traffic for multiple VLANs.

The BIG-IP^® system supports Link Layer Discovery Protocol (LLDP). LLDP is a Layer 2 industry-standard protocol (IEEE 802.1AB) that enables a network device such as the BIG-IP system to advertise its identity and capabilities to multi-vendor neighbor devices on a network. The protocol also enables a network device to receive information from neighbor devices.

LLDP transmits device information in the form of LLDP messages known as LLDP Data Units (LLDPDUs). In general, this protocol:

• Advertises connectivity and management information about the local BIG-IP device to neighbor devices on the same IEEE 802 LAN.
• Receives network management information from neighbor devices on the same IEEE 802 LAN.
• Operates with all IEEE 802 access protocols and network media.

Using the BIG-IP Configuration utility or tmsh, you can configure the BIG-IP system interfaces to transmit or receive LLDPDUs. More specifically, you can:

• Specify the exact content of LLDPDUs that a BIG-IP system interface transmits to a neighbor device. You specify this content by configuring the LLDP Attributes setting on each individual interface.
• Globally specify the frequencies of various message transmittal properties, and specify the number of neighbors from which each interface can receive messages. These properties apply to all interfaces on the BIG-IP system.

This figure shows a local LLDP-enabled BIG-IP system, configured to both transmit and receive LLDP messages from neighbor devices on a LAN.

A local BIG-IP system that transmits and receives LLDPDUs

Each interface on the BIG-IP^® system has a set of properties that you can configure, such as enabling or disabling the interface, setting the requested media type and duplex mode, and configuring flow control. Configuring the properties of each interface is one of the first tasks you do after running the Setup utility on the BIG-IP system. While you can change some of these properties, such as media speed and duplex mode, you cannot change other properties, such as the media access control (MAC) address.

Before configuring interface properties, it is helpful to understand interface naming conventions. Only users with either the Administrator or Resource Administrator user role can create and manage interfaces.

For reliability reasons, you can configure a feature known as interface mirroring. When you configure interface mirroring, you cause the BIG-IP^® system to copy the traffic on one or more interfaces to another interface that you specify. By default, the interface mirroring feature is disabled.

When a BIG-IP^® system interface receives LLDP messages from neighbor devices, the BIG-IP system displays chassis, port, and system information about the content of those messages. Specifically, the system displays values for the standard TLVs for each neighbor. These TLVs are:

Chassis ID

Identifies the chassis containing the IEEE 802 LAN station associated with the transmitting LLDP agent.

Port ID

Identifies the port component of the media service access point (MSAP) identifier associated with the transmitting LLDP agent.

Port description

An alpha-numeric string that describes the interface.

System name

An alpha-numeric string that indicates the administratively-assigned name of the neighbor device.

System description

An alpha-numeric string that is the textual description of the network entity. The system description should include the full name and version identification of the hardware type, software operating system, and networking software of the neighbor device.

System capabilities

The primary functions of the system and whether these primary functions are enabled.

Management address

An address associated with the local LLDP agent used to reach higher layer entities. This TLV might also include the system interface number that is associated with the management address, if known.

After you have configured the interfaces on the BIG-IP^® system, one of the primary tasks you perform is to assign those interfaces to the virtual LANs (VLANs) that you create. A VLAN is a logical subset of hosts on a local area network (LAN) that reside in the same IP address space. When you assign multiple interfaces to a single VLAN, traffic destined for a host in that VLAN can travel through any one of these interfaces to reach its destination. Conversely, when you assign a single interface to multiple VLANs, the BIG-IP system can use that single interface for any traffic that is intended for hosts in those VLANs.

Another powerful feature that you can use for BIG-IP system interfaces is trunking, with link aggregation. A trunk is an object that logically groups physical interfaces together to increase bandwidth. Link aggregation, through the use of the industry-standard Link Aggregation Control Protocol (LACP), provides regular monitoring of link status, as well as failover if an interface becomes unavailable.

Finally, you can configure the BIG-IP system interfaces to work with one of the spanning tree protocols (STP, RSTP, and MSTP). Spanning tree protocols reduce traffic on your internal network by blocking duplicate routes to prevent bridging loops.