Hi,

I am trying to setup a port trunk between two CRS112 switches but I am not able to get it working correctly.

On both switches I have done the following:
The two switches are then connected SFP11 to SFP11 and SFP12 to SFP12 but I am not able to pass traffic (although MDB looks to be populated correctly). If I disable one of the SFP interfaces so the trunk only contains a single, active link then the traffic passes.

What am I missing?

Many thanks.

You should not add trunked interfaces (sfp11 and sfp12) to the bridge1 ... only the trunk interface (trunk1).

The bridge should operate through trunk1 interface and only lower layers (switch chip) should be aware of what trunk1 really is.

You should not add trunked interfaces (sfp11 and sfp12) to the bridge1 ... only the trunk interface (trunk1).

The bridge should operate through trunk1 interface and only lower layers (switch chip) should be aware of what trunk1 really is.

@mkx: Thanks for that, makes perfect sense. Will give it a try later when I have access to the switches and feed back.

Sad to say this is not working. When trying to add the trunk to the bridge instead of the individual ports I am getting this message:
Any thoughts, please?

Many thanks.

I have the same problem. I discovered that if I disable the spaning tree, I can make it work. But I did not see this in mikrotik documentation

Now wait, that's two different issues, not the same one.

One issue is that the trunking can either be done at bridge level (in software running at CPU) or at switch chip level (in hardware), but not both at the same time, because the decision through which physical interface to run the frame must be done at the same place for frames sent by the CPU and frames forwarded from other interfaces (ports) of the switch chip. So if the decision is to let the switch chip handle the trunking, the trunkX port must be a member port of the bridge as @mkx wrote. So if RouterOS doesn't accept that, it is a bug.

@squeezypiano, can you check whether when you type /interface bridge port add interface= in the CLI (terminal window or ssh) while the trunk has previously been created using /interface ethernet switch trunk add ... and press the [TAB] key, RouterOS suggests you the trunk interface name among the choices? And if not, what about /interface print?

Another issue is how STP makes friends with trunking in hardware. For sure the CRS1xx/2xx switch chips do not support MSTP in hardware so if you activate it on a bridge, direct forwarding in switch chip between member interfaces of that bridge is disabled, but that should by itself not affect the ability to set up a trunk at switch chip level. Older STP flavors are supported by the switch chip itself in hardware, however there may be some headache associated with the trunking. Normally the trunk as a whole must be handled as a single logical port by the STP (otherwise STP would shut down all the member ports but one), so if the hardware STP in the switch chip didn't respect this, there would be an issue. And I agree that regarding this aspect, the manual is audibly silent.