Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 
ON THIS PAGE
 

Physical Interface Properties

Use this topic to configure various properties of physical interfaces on your device. Read on to configure properties such as interface descriptions, interface speeds, and accounting profiles for physical interfaces.

Physical Interface Properties Overview

The software driver for each network media type sets reasonable default values for general interface properties. These properties include the interface’s maximum transmission unit (MTU) size, receive and transmit leaky bucket properties, and speed.

To modify any of the default general interface properties, include the appropriate statements at the [edit interfaces interface-name] hierarchy level.

Configure the Interface Description

You can include a text description of each physical interface in the configuration file. Any descriptive text you include is displayed in the output of the show interfaces commands. The interface description is also exposed in the ifAlias Management Information Base (MIB) object. It has no impact on the interface’s configuration.

To add a text description, include the description statement at the [edit interfaces interface-name] hierarchy level. The description can be a single line of text. If the text contains spaces, enclose it in quotation marks.

For example:

Note:

You can configure the extended DHCP relay to include the interface description in the option 82 Agent Circuit ID suboption.

To display the description from the router or switch CLI, use the show interfaces command:

To display the interface description from the interfaces MIB, use the snmpwalk command from a server. To isolate information for a specific interface, search for the interface index shown in the SNMP ifIndex field of the show interfaces command output. The ifAlias object is in ifXTable.

For information about describing logical units, see Adding a Logical Unit Description to the Configuration.

How to Specify an Aggregated Interface

An aggregated interface is a group of interfaces. To specify an aggregated Ethernet interface, configure aex at the [edit interfaces] hierarchy level, where x is an integer starting at 0.

If you are configuring VLANs for aggregated Ethernet interfaces, you must include the vlan-tagging statement at the [edit interfaces aex] hierarchy level to complete the association.

Interface Speed

The interface speed is the maximum amount of data that can travel through an interface per second. An interface speed ending in m is in megabits per second (Mbps). A link speed ending in g is in gigabits per second (Gbps).

Configuring the Interface Speed on Ethernet Interfaces

For M Series and T Series Fast Ethernet 12-port and 48-port PIC interfaces, the management Ethernet interface (fxp0 or em0), and the MX Series Tri-Rate Ethernet copper interfaces, you can explicitly set the interface speed. The Fast Ethernet, fxp0, and em0 interfaces can be configured for 10 Mbps or 100 Mbps (10m | 100m). The MX Series Tri-Rate Ethernet copper interfaces can be configured for 10 Mbps, 100 Mbps, or 1 Gbps (10m | 100m | 1g). For information about management Ethernet interfaces and to determine the management Ethernet interface type for your router, see Understanding Management Ethernet Interfaces and Supported Routing Engines by Router.

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level.
  2. To configure the speed, include the speed statement at the [edit interfaces interface-name] hierarchy level.
Note:

  • By default, the M Series and T Series routers management Ethernet interface autonegotiates whether to operate at 10 megabits per second (Mbps) or 100 Mbps. All other interfaces automatically choose the correct speed based on the PIC type and whether the PIC is configured to operate in multiplexed mode (using the no-concatenate statement in the [edit chassis] configuration hierarchy.

  • When you manually configure Fast Ethernet interfaces on the M Series and T Series routers, link mode and speed must both be configured. If both these values are not configured, the router uses autonegotiation for the link and ignores the user-configured settings.

  • If the link partner does not support autonegotiation, configure either Fast Ethernet port manually to match its link partner's speed and link mode. When the link mode is configured, autonegotiation is disabled.

  • On MX Series routers with tri-rate copper SFP interfaces, if the port speed is negotiated to the configured value and the negotiated speed and interface speed do not match, the link will not be brought up.

  • When you configure the Tri-Rate Ethernet copper interface to operate at 1 Gbps, autonegotiation must be enabled.

  • Starting with Junos OS Release 11.4, half-duplex mode is not supported on Tri-Rate Ethernet copper interfaces. When you include the speed statement, you must include the link-mode full-duplex statement at the same hierarchy level.

See Also

Configure Interface Speeds for PTX10003 Routers and QFX5220 Switches

For a PTX10003 routers and QFX5220 switches, configure the port speed at the [edit chassis] level rather than the [edit interface] level.
  1. Navigate to the configuration hierarchy of the FPC slot number, PIC number, and port number you want to configure.
  2. To configure a port to operate at a specific speed:

    For example, to configure the interface et-1/0/3 to operate as a 100-Gigabit Ethernet port:

  3. (Optional) You can channelize the interface into sub-ports. The interface speed of each sub-port is based on the speed you configure for the main port. The default number of sub-ports is 1 (a non-channelized port). The maximum number of sub-ports depends on your device, the line card, and the port number. To channelize the port, include the number-of-sub-ports statement:

    For example:

    Since we configured the interface et-1/0/3 to have a speed of 100 Gbps, each of the four sub-ports has a speed of 25 Gbps. The four sub-ports are et-1/0/3:0, et-1/0/3:1, et-1/0/3:2, and et-1/0/3:3.

Forward Error Correction (FEC)

SUMMARY Forward error correction (FEC) improves the reliability of the data transmitted by your device. When FEC is enabled on an interface, that interface sends redundant data. The receiver accepts data only where the redundant bits match, which removes erroneous data from the transmission. Junos OS Evolved enables you (the network administrator) to configure Reed-Solomon FEC (RS-FEC) and BASE-R FEC on Ethernet interfaces. RS-FEC is compliant with IEEE 802.3-2015 Clause 91. BASE-R FEC is compliant with IEEE 802.3-2015 Cause 74.

Benefits of FEC

When you configure FEC on Ethernet interfaces, FEC improves your device function in these ways:

  • Enhances the reliability of the connection

  • Enables the receiver to correct transmission errors without requiring retransmission of the data

  • Extends the reach of optics

Overview

By default, Junos OS Evolved enables or disables FEC based on the plugged-in optics. For instance, Junos OS Evolved enables RS-FEC for 25 Gigabit (Gb) or 50 Gb SR4 optics and disables RS-FEC for 25 Gb or 50 Gb LR4 optics. You can override the default behavior and explicitly enable or disable FEC. You must disable FEC mode if you do not want it assigned by default.

You can enable or disable RS-FEC for 25-, 50-, and 100-Gigabit Ethernet (GbE) interfaces. You can enable or disable BASE-R FEC for 25GbE and 50GbE interfaces. If you enable or disable FEC, this behavior applies to any 25GbE or 50GbE optical transceiver installed in the port associated with the interface. You can configure FEC clauses CL74 on 25 Gb and 50 Gb interfaces and CL91 on 25 Gb, 50 Gb, or 100 Gb interfaces. Because the FEC clauses are applied by default on these interfaces, you must disable the FEC clauses if you do not want to apply them.

Note:

FEC is always enabled on 200GbE and 400GbE interfaces. You cannot disable it.

If there is an FEC mismatch between pairs of nodes, the link between nodes can go down. To prevent the nodes from going down, you must reconfigure them.

For instance, consider two peer nodes, Node1 and Node2. Node1 is running Junos OS Evolved Release 21.1R1, where the default is FEC91. The peer node (Node2) is running Junos OS Evolved Release 20.1R1, where the default is FEC74. The link between the two nodes will go down because the FEC modes don't match. To enable the link to come back up, you must manually change the FEC on one of the nodes.

Configure FEC

To disable or enable an FEC mode on an interface and any associated interfaces, complete the relevant action:

  1. To disable FEC mode:
  2. To enable an FEC mode:

    Alternatively:

  3. To view the FEC mode on an interface, use the show interfaces interface-name command. The output lists FEC statistics for that particular interface, including the number of FEC corrected errors, the number of FEC uncorrected errors, and the type of FEC that was disabled or enabled.

Interface Aliases

Overview

An interface alias is a textual description of a logical unit on a physical interface. An alias enables you to give a single meaningful and easily identifiable name to an interface. Interface aliasing is supported only at the unit level.

The alias name is displayed instead of the interface name in the output of all show, show interfaces, and other operational mode commands. Configuring an alias for a logical unit of an interface has no effect on how the interface operates on the device.

When you configure the alias name of an interface, the CLI saves the alias name as the value of the interface-name variable in the configuration database. When the operating system processes query the configuration database for the interface-name variable, the exact value of the interface-name variable is returned instead of the alias name for system operations and computations.

Configuration

To specify an interface alias, use the alias statement at the [edit interfaces interface-name unit logical-unit-number] hierarchy level. Start the alias name with a letter followed by letters, numbers, dashes, dots, underscores, colons, or slashes. Avoid starting the alias with any part of a valid interface name. Use between 5 and 128 characters.

For example:

Note:

If you configure the same alias name on more than one logical interface, the router displays an error message, and the commit fails.

You can use interface alias names to make it easy to see the roles interfaces play in your configuration. For example, to make it easy to identify satellite connection interfaces:

  1. Group physical interfaces as one aggregated interface using a link aggregation group (LAG) or LAG bundle. Name that aggregated interface sat1 to show it is a satellite connection interface.
  2. Select a logical interface as a member of the LAG bundle or the entire LAG. Name that interface et-0/0/1 to represent a satellite device port or a service instance.
  3. You can combine the satellite name and the interface name aliases to wholly represent the satellite port name. For example, you could give your satellite port the alias sat1:et-0/0/1.

Interface Encapsulation on Physical Interfaces

Point-to-Point Protocol (PPP) encapsulation is the default encapsulation type for physical interfaces. You don't need to configure encapsulation for physical interfaces that support PPP encapsulation, because PPP is used by default.

For physical interfaces that do not support PPP encapsulation, you must configure an encapsulation to use for packets transmitted on the interface. On a logical interface, you can optionally configure an encapsulation type that Junos OS Evolved uses within certain packet types.

Encapsulation Capabilities

When you configure a point-to-point encapsulation (such as PPP or Cisco HDLC) on a physical interface, the physical interface can have only one logical interface (that is, only one unit statement) associated with it. When you configure a multipoint encapsulation (such as Frame Relay), the physical interface can have multiple logical units, and the units can be either point-to-point or multipoint.

Ethernet circuit cross-connect (CCC) encapsulation for Ethernet interfaces with standard Tag Protocol Identifier (TPID) tagging requires that the physical interface have only a single logical interface. Ethernet interfaces in VLAN mode can have multiple logical interfaces.

For Ethernet interfaces in VLAN mode, VLAN IDs are applicable as follows:

  • VLAN ID 0 is reserved for tagging the priority of frames.

  • For encapsulation type vlan-ccc, VLAN IDs 1 through 511 are reserved for normal VLANs. VLAN IDs 512 and above are reserved for VLAN CCCs.

  • For Ethernet interfaces, you can configure flexible Ethernet services encapsulation on the physical interface. For interfaces with flexible-ethernet-services encapsulation, all VLAN IDs are valid. VLAN IDs from 1 through 511 are not reserved.

The upper limits for configurable VLAN IDs vary by interface type.

When you configure a translational cross-connect (TCC) encapsulation, some modifications are needed to handle VPN connections over dissimilar Layer 2 and Layer 2.5 links and terminate the Layer 2 and Layer 2.5 protocol locally. The device performs the following media-specific changes:

  • Point-to-Point Protocol (PPP) TCC—Both Link Control Protocol (LCP) and Network Control Protocol (NCP) are terminated on the router. Internet Protocol Control Protocol (IPCP) IP address negotiation is not supported. Junos OS Evolved strips all PPP encapsulation data from incoming frames before forwarding them. For output, the next hop is changed to PPP encapsulation.

  • Cisco High-Level Data Link Control (HDLC) TCC—Keepalive processing is terminated on the router. Junos OS Evolved strips all Cisco HDLC encapsulation data from incoming frames before forwarding them. For output, the next hop is changed to Cisco HDLC encapsulation.

  • Frame Relay TCC—All Local Management Interface (LMI) processing is terminated on the router. Junos OS Evolved strips all Frame Relay encapsulation data from incoming frames before forwarding them. For output, the next hop is changed to Frame Relay encapsulation.

Configure Encapsulation on a Physical Interface

To configure encapsulation on a physical interface:

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level.
  2. Configure the encapsulation type.

Configure Interface Encapsulation on PTX Series Routers

This topic describes how to configure interface encapsulation on PTX Series Packet Transport Routers. Use the flexible-ethernet-services configuration statement to configure different encapsulation for different logical interfaces under a physical interface. With flexible Ethernet services encapsulation, you can configure each logical interface encapsulation without range restrictions for VLAN IDs.

Supported encapsulations for physical interfaces include:

  • flexible-ethernet-services

  • ethernet-ccc

  • ethernet-tcc

In Junos OS Evolved, the flexible-ethernet-services encapsulation is not supported on PTX10003 devices.

Supported encapsulations for logical interfaces include:

  • ethernet

  • vlan-ccc

  • vlan-tcc

Note:

PTX Series Packet Transport Routers do not support extended-vlan-cc or extended-vlan-tcc encapsulation on logical interfaces. Instead, you can configure a tag protocol ID (TPID) value of 0x9100 to achieve the same results.

To configure flexible Ethernet services encapsulation, include the encapsulation flexible-ethernet-services statement at the [edit interfaces et-fpc/pic/port] hierarchy level. For example:

Enable SNMP Notifications on Physical Interfaces

By default, Junos OS Evolved sends Simple Network Management Protocol (SNMP) notifications when the state of an interface or a connection changes. You can enable or disable SNMP notifications based on your requirements.

To explicitly enable sending SNMP notifications on the physical interface:

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level:
  2. Configure the traps option to enable SNMP notifications when the state of the connection changes.

To disable SNMP notifications on the physical interface:

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level:

  2. Configure the no-traps option to disable SNMP notifications when the state of the connection changes.

Accounting for Physical Interfaces

Devices running Junos OS Evolved can collect various kinds of data about traffic passing through the device. You (the systems administrator) can set up one or more accounting profiles that specify some common characteristics of this data. These characteristics include the following:

  • The fields used in the accounting records

  • The number of files that the router or switch retains before discarding, and the number of bytes per file

  • The polling period that the system uses to record the data

Overview

There are two types of accounting profiles: filter profiles and interface profiles. Configure the profiles using statements at the [edit accounting-options] hierarchy level.

Configure filter profiles by including the filter-profile statement at the [edit accounting-options] hierarchy level. You apply filter profiles by including the accounting-profile statement at the [edit firewall filter filter-name] and [edit firewall family family filter filter-name] hierarchy levels.

Configure interface profiles by including the interface-profile statement at the [edit accounting-options] hierarchy level. Read on to learn how to configure interface profiles.

Configure an Accounting Profile for a Physical Interface

Before You Begin

Configure an accounting data log file at the [edit accounting-options] hierarchy level. The operating system logs the statistics in the accounting data log file.

Configuration

Configure an interface profile to collect error and statistic information for input and output packets on a particular physical interface. The interface profile specifies the information that the operating system writes to the log file.

To configure an interface profile:

  1. Navigate to the [edit accounting-options interface-profile] hierarchy level. Include the profile-name to name the interface profile.
  2. To configure which statistics should be collected for an interface, include the fields statement.
  3. Each accounting profile logs its statistics to a file in the /var/log directory. To configure which file to use, use the file statement.
    Note:

    You must specify a file statement for the interface profile that has already been configured at the [edit accounting-options] hierarchy level.
  4. The operating system collects statistics from each interface with an accounting profile enabled. It collects the statistics once per interval time specified for the accounting profile. The operating system schedules statistics collection time evenly over the configured interval. To configure the interval, use the interval statement:
    Note:

    The minimum interval allowed is 1 minute. Configuring a low interval in an accounting profile for a large number of interfaces might cause serious performance degradation.
  5. Apply the interface profile to a physical interface by including the accounting-profile statement at the [edit interfaces interface-name] hierarchy level. The operating system performs the accounting on the interfaces that you specify.

How to Display the Accounting Profile

Purpose

To display the configured accounting profile of a particular physical interface at the [edit accounting-options interface-profile profile-name] hierarchy level that has been configured with the following:

  • interface-name—et-1/0/1

  • Interface profile —if_profile

  • File name—if_stats

  • Interval—15 minutes

Action

  • Run the show command at the [edit interfaces et-1/0/1] hierarchy level.

  • Run the show command at the [edit accounting-options] hierarchy level.

Meaning

The configured accounting and its associated set options are displayed as expected.

Disable a Physical Interface

You can disable a physical interface, marking it as being down, without removing the interface configuration statements from the configuration.

How to Disable a Physical Interface

CAUTION:

Dynamic subscribers and logical interfaces use physical interfaces for connection to the network. You can set the interface to disable and commit the change while dynamic subscribers and logical interfaces are still active. This action results in the loss of all subscriber connections on the interface. Use care when disabling interfaces.

To disable a physical interface:

  1. In configuration mode, go to the [edit interfaces interface-name] hierarchy level.
  2. Include the disable statement.

    For example:

    Note:

    When you use the disable statement at the edit interfaces hierarchy level, depending on the PIC type, the interface might or might not turn off the laser. Older PIC transceivers do not support turning off the laser, but newer Gigabit Ethernet PICs with SFP and XFP transceivers do support it. On a device with newer PICs, the laser turns off when the interface is disabled.
    Laser Warning:

    Do not stare into the laser beam or view it directly with optical instruments even if the interface has been disabled.
  3. Alternatively, include the unused statement. If you configure a port as unused, no interfaces are created for that port irrespective of the port profile configuration for that port.
    1. For PTX10003 routers and QFX5220 switches:

      For example:

    2. For all other devices running Junos OS Evolved:

      For example:

Example: Disable a Physical Interface

Sample interface configuration:

Disable the interface:

Verify the interface configuration:

Release History Table
Release
Description
21.1R1
Starting in Junos OS Evolved Release 21.1R1, the default FEC is FEC91. In earlier releases, the default is FEC74.
14.2
Starting with Junos OS Release 14.2 the auto-10m-100m option allows the fixed tri-speed port to auto negotiate with ports limited by 100m or 10mmaximum speed. This option must be enabled only for Tri-rate MPC port, that is, 3D 40x 1GE (LAN) RJ45 MIC on MX platform. This option does not support other MICs on MX platform.
11.4
Starting with Junos OS Release 11.4, half-duplex mode is not supported on Tri-Rate Ethernet copper interfaces. When you include the speed statement, you must include the link-mode full-duplex statement at the same hierarchy level.