Ethernet Shield... detecting cable connected

Projects Networking, Protocols, and Devices
1

Is there any way to determine if there's a cable in the RJ45 port of the ethernet shield before trying to connect?

I have an sketch that will run with or without the ethernet connected, but I'd like to avoid the 20s wait while trying to connect to the server if the cable isn't connected.

2

There isn't a way to detect the status of the interface with the w5100. The w5200 has the capability to determine if the physical interface is up or down, but you would need to modify the ethernet library to get that status.