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[MX/SRX] em0 or em1 interface physical link is down



Article ID: KB27820 KB Last Updated: 09 Feb 2015Version: 2.0

MX or SRX routers could show the em0 or em1 interface as down:

Physical interface: em1, Enabled, Physical link is Down

MX or SRX routers could show the em0 or em1 interface as down.


During Routing Engine bootup, em Ethernet hardware may not successfully complete autonegotiation with the Ethernet interface on the System Control Board (SCB) ethernet-switch.


In the shell, the command ifconfig em[0|1] will display the state of the interface. If the interface is hard down, re-initialize the interface using the ifconfig em[0|1] up command.

If the em interface cannot be brought up by the above method, there could be a faulty port/circuit on either the Routing Engine or the SCB.

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