Hi;
I’ve got two CRS354-48G-4S+2Q+ and a Q+DA0001 QSFP+ Link Cable. I’d like to link both Switches via this QSFP+ case in order to have a single 40G link between these switches.
What is the correct way to group the four 10G interfaces of a QSFP+ port into a single port?
Thanks
Frank-Christian Kruegel
You should ask the Technical Support whether the following cable (Q+BC0003-S+) can be used for that, or whether there is another such cable for this kind of task: https://mikrotik.com/product/q_bc0003_s#fndtn-specifications
But you already have 2 QSFP+ ports on each device (besides the 4 SFP+ ports). Are they not enough?
The OP does not want to break out, he just wants to connect to Q ports with the simple 40G DAC she has.
I think Mikrotik automatically configures the Q ports according to what you plug in.
I understood it such that the OP wants to bundle the 4 SFP+ ports to a Q port.
No, he said he wanted to group the 4 components of the Q port into 40G.
With some other brands you would have to execute a command to split a Q port or to merge the components back.
Man, a Q port is already 40G, internally consisting of 4x 10G.
See also the Q cable with the 40G modules at each end: https://mikrotik.com/product/q_da0001
That is the cable that he has.
I don’t know how the 40G port appears in the OS when you plug that cable in, I only saw a screenshot with it split.
The problem is that the QSFP+ ports show up as four individual SFP+ interfaces. If I connect two switches with a QSFP+ cable, I’ve got 4 individual links. This might cause loops etc so only one link would be used. I need to tell the switch chips that these 4 links belong together. How do I do this so the switch hardware gets used and not the processor?
Frank-Christian
My guess is that RouterOS already takes care of it. Not sure, but maybe it’s even industry-standardized in exactly this way. So, then maybe you don’t need to do anything. But to be 100% sure, you better should ask the Technical Support at https://help.mikrotik.com/servicedesk . Let us too know about the result 
It is not standard for a port to appear split when it is not used that way.
Yes, I too would not have expected such a splitted port as was described by the OP.
I personally have no experience with 40G yet, I only read sometime somewhere that 40G is physically realized by 4x 10G internally, but externally it should just be a single 40G port.
Just plugging a 40G cable seems to be working as expected for some people. Maybe it is a teething bug.
I’ve linked two CRS354 with a a QSFP+ DAC-Cable plugged into the top QSFP+ port and rebooted both switches.
The port’s interfaces show up as qsfpplus1-1 through qsfpplus1-4.
Is auto negotiation enabled on the ports?
It looks like “1” should appear as 40G and the others as down:
http://forum.mikrotik.com/t/crs326-24s-2q-rm-40g-passive-connection-with-huawei/132620/1