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Interface Types and Configuration

Learn how to configure interfaces on your Juniper MX204, MX301, MX304, MX10004, or MX10008 router.

Configuring interfaces on a Juniper MX204, MX301, MX304, MX10004, or MX10008 router involves entering configuration mode (clithen configure), setting the interface type (ge,xe, et), assigning a logical unit, and setting the encapsulation or family (inet for L3, bridge for L2) before using committo apply changes. Key commands include set interfaces [name] unit 0 family inet address [ip].

Interface Types

Interface Types

On MX Series routers, physical interfaces follow this naming format:

Field Definitions

  1. <type>

    Identifies the interface speed:

    • ge — 1-Gigabit Ethernet
    • xe — 10-Gigabit Ethernet
    • et — 25-Gigabit Ethernet and higher

  2. <fpc> (Flexible PIC Concentrator slot)

    Specifies the line card slot number.

    • On fixed-form-factor platforms (for example, MX301 or MX304), this value is always 0.

  3. <pic> (Physical Interface Card)

    Identifies the Trio ASIC (Packet Forwarding Engine) instance on the line card.

    • Example: On an LC9600 line card, six Trio 6 ASICs are present, so PIC values range from 0 to 5.
    • On an MX301 router, only one Trio ASIC is present, so the PIC value is always 0.

  4. <port>

    Indicates the physical port that contains the pluggable transceiver (such as SFP or QSFP).

  5. [:channel] (optional)

    Required only when channelization is configured.

    • The channel number depends on the port and optic capabilities.
    • Valid values typically range from 0 through 7.

Logical Interfaces

A logical interface is derived by appending a unit number to the physical interface name:

Verifying Interface Mapping

To view hardware-to-interface mappings:

  • Use an operational command to display PIC assignments for each slot.
  • Use another command to list ports for a specific FPC and PIC, including supported speeds for multi-rate ports.

These commands help verify how ports, PICs, and line cards map to interface names.

For aggregated Ethernet (AE) interfaces (also called link aggregation groups [LAGs] or Ethernet bundles), configure the number of AE interfaces supported on the chassis before using them. Configure this value under the [edit chassis] hierarchy. You typically set this value once, but you can modify it later without disrupting traffic.

Aggregated Ethernet (AE) interfaces use the following naming format:

<lag-id> specifies the interface identifier. Valid values range from 0 through 4091.

The lag-id is independent of the device-count configured under [edit chassis], which defines the maximum number of AE interfaces supported on the chassis. For example, if the device count is 2, you can configure two AE interfaces with any valid IDs, such as ae0 and ae1325.

Configuration

The following are specific interface types and options:

  1. Ethernet interface (ge, xe or et): You may need to set the framing to LAN or WAN:

  2. Aggregated Ethernet (AE): For link aggregation (LACP):

  3. Disable/Enable Port:

  4. Enter configuration mode.

  5. Set Interface Description (optional but recommended).

  6. Configure Layer 3 (IP) Interface.

  7. Configure Layer 2 (Access) Interface.

  8. Commit the Configuration.

  9. Verify the configuration.