Hello guys,

I bought a L009UiGS to act as a switch for my RB5009 router. Between the units is a 20m cat6 cable. When I connect the cable to eth1 of the L009 I got a 100mb connection. When I connect the same cable, from the same port of the RB5009 to eth2 of the L009 I get a 1G connection. In the block diagram, of the L009 I can see that eth is directly connected to the CPU and that other ports are connected to the Switch chip. Does this have anything to do with the auto negotiating?

When I force both units to use 1G I can’t get a connection on eth1, eth2 just works as expected. When i connect an other device to eth1 from the L009 I can get a 1G link. So the L009 eth1 port can do 1G.

That leaves the 20m cat6 cable as main suspect, but why does it work on eth2 and not on eth1?

My first attempt would also be to try another cable.

Sometimes you can get into real border conditions due to some combination of factors making it work, or not.

That’s one of the things I going to test but the existing cable cannot easily be replaced so I really would like it to work. The reason why I would like to connect to eth1 is that the next step is add a Poe injector at the RB5009 side. (Or replace the RB5009UG+S+IN for a RB5009UPr+S+IN)

Is there any command except the “interface Ethernet monitor” that gives more insight in why the auto negotiation fails?

You can always run a loose cable next to the existing one to test.
Or add that POE injector already. It might make already enough difference (but still that cable would remain suspicious).