Interface Descriptors

When you configure an interface, you are specifying the properties for a physical interface descriptor. In most cases, the physical interface descriptor corresponds to a single physical device and consists of the following parts:

• The interface name, which defines the media type
• The slot in which the Flexible PIC Concentrator (FPC) is located
• The location on the FPC in which the PIC is installed
• The PIC port
• The channel and logical unit numbers of the interface (optional)

Each physical interface descriptor can contain one or more logical interface descriptors. These allow you to map one or more logical (or virtual) interfaces to a single physical device. Creating multiple logical interfaces is useful for ATM, Frame Relay, and Gigabit Ethernet networks, in which you can associate multiple virtual circuits, data-link connections, or virtual LANs (VLANs) with a single interface device.

Each logical interface descriptor can have one or more family descriptors to define the protocol family that it is associated with and are allowed to run over the logical interface. The following protocol families are supported:

• Internet Protocol version 4 (IPv4)
• Internet Protocol version 6 (IPv6)
• Circuit cross-connect (CCC)
• Translational cross-connect (TCC)
• International Organization for Standardization (ISO)
• Multilink Frame Relay (MLFR)
• Multilink PPP (MLPPP)
• Multiprotocol Label Switching (MPLS)
• Trivial Network Protocol (TNP)

Each family descriptor can have one or more address entries, which associate a network address with a logical interface and hence with the physical interface.

You configure the various interface descriptors as follows:

• Configure the physical interface descriptor by including the interfaces interface-name statement.
• Configure the logical interface descriptor by including the unit statement within the interfaces interface-name statement.
• Configure the family descriptor by including the family statement within the unit statement.
• Configure address entries by including the address statement within the family statement.
• Configure tunnels by including the tunnel statement within the unit statement.