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    (auto-negotiation | no-auto-negotiation) <remote-fault (local-interface-online | local-interface-offline)>;

    Hierarchy Level

    [edit interfaces interface-name ether-options],[edit interfaces interface-name gigether-options],[edit interfaces ge-pim/0/0 switch-options switch-port port-number]

    Release Information

    Statement introduced in Junos OS Release 7.6.

    Statement introduced in Junos OS Release 8.4 for J Series Services Routers.

    Statement introduced in Junos OS Release 9.0 for EX Series switches.

    Statement introduced in Junos OS Release 12.2 for ACX Series Universal Access Routers.


    For Gigabit Ethernet interfaces on M Series, MX Series, T Series, TX Matrix routers, and ACX Series routers explicitly enable autonegotiation and remote fault. For EX Series switches and J Series Services Routers, explicitly enable autonegotiation only.

    • auto-negotiation—Enables autonegotiation. This is the default.
    • no-auto-negotiation—Disable autonegotiation. When autonegotiation is disabled, you must explicitly configure the link mode and speed.

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

    Note: On EX Series switches, an interface configuration that disables autonegotiation and manually sets the link speed to 1 Gbps is accepted when you commit the configuration; however, if the interface you are configuring is a Tri-Rate Ethernet copper interface, the configuration is ignored as invalid and autonegotiation is enabled by default.

    To correct the invalid configuration and disable autonegotiation:

    1. Delete the no-auto-negotiation statement and commit the configuration.
    2. Set the link speed to 10 or 100 Mbps, set no-auto-negotiation, and commit the configuration.

    On J Series Services Routers with universal Physical Interface Modules (uPIMs) and on EX Series switches, if the link speed and duplex mode are also configured, the interfaces use the values configured as the desired values in the negotiation. If autonegotiation is disabled, the link speed and link mode must be configured.

    Note: On T4000 routers, the auto-negotiation command is ignored for interfaces other than Gigabit Ethernet.


    Autonegotiation is automatically enabled. No explicit action is taken after the autonegotiation is complete or if the negotiation fails.


    remote-fault (local-interface-online | local-interface-offline)—(Optional) For M Series, MX Series, T Series, TX Matrix routers, and ACX Series routers only, manually configure remote fault on an interface.

    Default: local-interface-online

    Required Privilege Level

    interface—To view this statement in the configuration.

    interface-control—To add this statement to the configuration.

    Published: 2012-12-11