Switching

The specification sheet of the Ex 4200 mentions the 'downshift'  option.

This can limit the advertised speed for autonegotation on all ports.

However, where is the command to do this ?

I was told to use the port speed setting on the interface, but with autonegotiation this becomes the 'preferred' speed.

Anyone has an answer ?

Luc

Not sure if this is what you are looking for, but it sounds like it. You can configure it on each port now, but it will have no effect until JUNOS 9.6 .

ge-0/0/0 {
    ether-options {
        speed {
            auto-negotiation 10m-100m;
        }
    }
    unit 0 {
        family ethernet-switching;
    }
}