I have available a Juniper QFX5100-48S switch (48 SFP 10G ports, 6 QSFP ports) that I cannot join into our network since an SFP DAC 10G cable connecting it to an SFP port on a HP V1810-48G switch does not work (the web panel on the HP switch says that on the connected port the link is down). The very same cable successfully negotiates a connection between the HP switch and a server with a 10G Ethernet port once the server port is forced via OS to 1G so my idea was to somehow force the SFP port on the QFX5100 to 1G speed (unsetting the auto-negotiation on the HP switch for the SFP ports is not allowed from the web panel).
The only instructions I could find to do that (here) on the Juniper switch state that, once logged in the management console and entered the CLI context, then configure, then edit interface, there should be possible to issue set xe-0/0/0 speed 1g to force 1G negotiation for the 10G port 0, which I cannot - there is not any speed subcommand available.
Can someone tell me what I am doing wrong or it is simply not possible?