This article explains why a router is not recognizing the speed configuration under gigether-options .

When configuring an interface on an M-series router, you may have a configuration that looks something like this:

ge-1/0/0 {
    gigether-options {
          link-mode full-duplex;
          speed 100m ;

You are configuring for 100m, but when you run the show interfaces extensive command, you notice in the output that the speed is shown as 1000m instead:

Physical interface: ge-1/0/0, Enabled, Physical link is Up
Interface index: 149, SNMP ifIndex: 672, Generation: 152
Description: LAB
Link-level type: Ethernet, MTU: 1518, Speed: 1000mbps ,

When speed is configured under gigether-options , the router does not recognize the configuration.

This behavior is expected. The speed configuration, while allowed by the Junos OS, cannot be configured on an M-series router. The speed configuration can be configured, however, on MX series and EX series devices with Tri-Rate Copper small form-factor pluggable transceivers (SFPs).

Note: On an EX series device, the speed is set under ether-options , while on an MX series device, the speed is set under gigether-options .

If the speed configuration is configured on an M-series router, the router will ignore the configuration.

• gigether-options