Enhanced loopback options on 400ZR and 400G OpenZR+ optics

Before Junos OS Evolved 23.1 R1, only the Media Side Output loopback type was supported on the 400ZR and 400G OpenZR+ optics. From Junos OS Evolved 23.1 R1, the following three new loopback types are also supported:

Media Side Input: Loopback of the transceiver optical input signal back to its input.

Host Side Input: Loopback of the data packet signal output at the host side back to its input.

Host Side Output: Loopback of the data packet signal input at the host side back to its input.

You can use the loopback loopbacktype statement at the [edit interfaces interface-name optics-options] hierarchy level to configure the loopback type.