Approx 20 second renegotiation to 100mbps ethernet port on VH109

[Bankst]

When the physical link is broken on the systemcore ethernet, it takes approximately 20 seconds from physical reconnection for link status lights to be lit.

https://photos.app.goo.gl/A7XttpxrsixbN3jQA

Connecting to the DS port on the VH109, the negotiation time dropped to approximately 2 seconds.

A static IP address is used on all devices on the robot network

[rzblue]

To add more context, it looks like this may be an issue with the vh-109 specifically. I've seen this occur with orange pis when the pi's gigabit capable interface connects to one of the 10/100 ports. In that case, limiting the negotiated link rate sped up the time-to-link dramatically.

[jwbonner]

occur with orange pis

FWIW, we see exactly the same effect when connecting to the VH-109 over Ethernet from macOS too. Manually setting the link speed to 100 Mbps is required to connect in a reasonable length of time.