Forcibly bringing up a fiber port

CAUTION:

The following operations on a fiber port will cause link updown events before the port finally stays up:

Configure the port up-mode command and the speed or duplex command at the same time.
Install or remove fiber links or transceiver modules after you forcibly bring up the fiber port.

IMPORTANT:

Copper ports do not support this feature.

As shown in Figure 1, a fiber port typically uses separate fibers for transmitting and receiving packets. The physical state of the fiber port is up only when both transmit and receive fibers are physically connected. If one of the fibers is disconnected, the fiber port does not work.

To enable a fiber port to forward traffic over a single link, you can use the port up-mode command. This command brings up a fiber port by force, even when no fiber links or optical modules are present. If one fiber link is present and up, the fiber port can forward packets over the link unidirectionally.

Figure 1: Forcibly bring up a fiber port

Configuration restrictions and guidelines

The port up-mode command is mutually exclusive with either of the shutdown and loopback commands.

Configuration procedure

To forcibly bring up a fiber port:

Step	Command	Remarks
1. Enter system view.	system-view	N/A
2. Enter Ethernet interface view.	interface interface-type interface-number	N/A
3. Forcibly bring up the fiber port.	port up-mode	By default, a fiber Ethernet port is not forcibly brought up, and the physical state of a fiber port depends on the physical state of the fibers.

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