I’ve recently started deploying the Juniper EX4300 in a large campus rollout (more on that in a future post) and during an forklift upgrade last night we ran into an interesting issue. We have some Wattstopper lighting control systems that require 10Mbps half-duplex connections. We quickly discovered that the Juniper EX4300 doesn’t support half duplex, it only supports full duplex.
If you have a look at the Juniper documentation for the ELS hardware you’ll notice the following statement half-way down the page.
That explains why we weren’t able to find the link-mode option in the CLI configuration under the interface branch.
In the end we were able to get the Wattstopper working at 10Mbps full duplex.
It’s not a huge deal but it could certainly get entertaining trying to connect some of the older HVAC and SCADA solutions that utilize much older 10Mbps NICs and hubs. There was a post here that suggests the issue is related to the PHY and MACSEC.
If I get additional feedback from Juniper I’ll post it here.