Hi
I have one RB3011 and want to connect to a CRS309 so I wounder if it is possible to use a XS+DA0001 cable between them
It says that the XS+DA0001 should work in the RB3011 but it is maybe only to a SFP port.. or?

I think that passive DACs require both connected devices to be of same SFP generation/variety ... as these DACs more or less simply connect appropriate SFP signal lines together. Many devices have SFP ports that are actually single rate (e.g. SFP+ only supports 10Gbps ... it's the module which can negotiate lower speeds on media side - e.g. 2.5Gbps over UTP cable)., so you can't plug an 1Gbps module to SFP+ port.
So I guess you'd need an active DAC to connect SFP ports of different generations (and make sure that active DAC supports both SFP and SFP+).

Hi,
Check:

https://help.mikrotik.com/docs/display/ ... patibility

I have a FS.com 10G DAC which works well (but is not supported) between a 4011 and a 3011 with the 4011 forced to 1G,
and is also working well between the 4011 and a 10G sfp+ on a non Mikrotik switch.

Virtually all of the Mikrotik sfp+ ports will run at either 10G or 1G.
(2.5G not so much, see above page for details)