Why Is a Non-Connected Interface Up?

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The loopback internal command may be configured on the interface to enable internal loopback detection. Therefore, the interface is Up.
You can run the display interface gigabitethernet 1/0/1 command in any view to check whether internal loopback detection is enabled on GE1/0/1.
display interface gigabitethernet 1/0/1
...
Port Mode: FORCE COPPER
Speed : 1000, Loopback: INTERNAL
Duplex: FULL, Negotiation: ENABLE
Mdi : AUTO, Flow-control: DISABLE
...
The command output shows that internal loopback detection is enabled on the interface.

Other related questions:
Why non-authentication cannot be used for the administrator on an AR
To improve the security of the AR, administrators are not allowed to use no-authentication.

Why are BGP connections re-established after the peer connect-interface command is configured
Currently, the switch does not support BGP dynamic capability negotiation. Therefore, if certain capabilities of the BGP peer are changed, the BGP connection is automatically disconnected and then the capabilities of the neighbor are renegotiated. If the peer connect-interface command is configured, the BGP session needs to be set up by designating the egress. Therefore, the source address of the TCP connection may be changed and the TCP connection needs to be re-established by using the new source address.

Why is the BGP connection not interrupted immediately after the interfaces connecting two peers are shut down
When External Border Gateway Protocol (EBGP) peers are directly connected and the ebgp-interface-sensitive command is run in the Border Gateway Protocol (BGP) view, the BGP peer relationship is interrupted immediately after the interfaces connecting the two peers are shut down. By default, the ebgp-interface-sensitive command is run in the BGP view. In other cases, the BGP peer relationship is not interrupted until the Hold timer times out.

Why are BGP connections reestablished after the peer connect-interface command is executed on S series switches
Currently, S series switches do not support BGP dynamic capability negotiation. Therefore, when capabilities of the BGP neighbor are changed, the BGP connection is automatically cut off and then the capabilities of the neighbor are renegotiated. If the peer connect-interface command is configured, the BGP session needs to be set up by designating the egress. Therefore, the source address of the TCP connection may be changed and the TCP connection needs to be re-established by using the new source address.

Cause why the attenuation of the EVOA on a non-service channel of the M40V board connected to the D40 board is set to the maximum in the dummy light scenario
This setting ensures that the receive optical power is small to prevent a sharp optical power change on adjacent service channels.

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