When I connect RB3011 SFP on the CSS610 SFP+ with the direct attached cable XS+DA001 it doesn’t work. If the same cable connects 2 CSS610 it works. If the same cable connects RB3011 with CSS106-5G-1Sr2 it works. How to make it work between RB3011 and CSS610?
Direct attach cable generally only works when interfaces on both ends are the same generation, i.e. both are SFP (1Gbps) or both are SFP+ (10Gbps) or both are SFP28 (25Gbps).
Sometimes it’s possible to use DAC even if interfaces are different … if both devices dupport setting interface rate manually. In which case one should set it to same value … the lower value of both ends. In case of linking RB3011 and CSS610 that would be 1Gbps.