Some data I cant find on the Datasheet:

Switch chip?
Ethernet-Ports: what speeds at what distance? Jumbo Frames?

CRS317-1G-16S+RM has more ports, better cpu and is cheaper. So?

As the product naming page explains:

• CRS series: 3
• total number of interfaces: 12
• number of combo 10G Ethernet/SFP ports: 4 (4C+ part of name)
• number of 5G/10G Ethernet ports: 8 (8XG part of name)

The mentioned CRS317-1G-16S+RM fetaures only 1Gbps ports (ethernet) or 10Gbps (SFP+). So it's like comparing apples to water-melons.

And don't let be lead away about device's CPU, it has nothing to do with frame switching. It might be used for routing, but these beasts are switches, not routers (don't let be lead away with the name either).

As the product naming page explains:

• CRS series: 3
• total number of interfaces: 12
• number of combo 10G Ethernet/SFP ports: 4 (4C+ part of name)
• number of 5G/10G Ethernet ports: 8 (8XG part of name)

The mentioned CRS317-1G-16S+RM fetaures only 1Gbps ports (ethernet) or 10Gbps (SFP+). So it's like comparing apples to water-melons.

And don't let be lead away about device's CPU, it has nothing to do with frame switching. It might be used for routing, but these beasts are switches, not routers (don't let be lead away with the name either).

Comparing a 10G MT Switch with another is "comparing apples to water-melons"? I know this CPUs do only limited routing. Still usefull to route e.g. a managment vlan.
Does this answer one of my questions ?

CRS312-4C+8XG has Marvell-98DX8212 switch chip and supports the same features as CRS317-1G-16S+ including 10218 byte Jumbo Frames.
Briefly, Ethernet interface link speeds are similar to S+RJ10 module:
https://i.mt.lv/cdn/rb_files/sfp_splusr ... 155011.pdf
We will update the CRS312-4C+8XG documentation regarding that.

CRS312-4C+8XG has Marvell-98DX8212 switch chip and supports the same features as CRS317-1G-16S+ including 10218 byte Jumbo Frames.
Briefly, Ethernet interface link speeds are similar to S+RJ10 module:
https://i.mt.lv/cdn/rb_files/sfp_splusr ... 155011.pdf
We will update the CRS312-4C+8XG documentation regarding that.

as seen the test results look like not correct speed that explain in brochure that is

"This switch has a great total non-blocking throughput of 120 Gbps, switching capacity of 240 Gbps and
forwarding rate of 178 Mpps. CRS312-4C+8XG-RM – built for professionals, great for everyone!"

and also spec show QCA9531 but your mention is it use Marvell-98DX8212
this make confusing the spec.

the crs312
https://mikrotik.com/product/crs312_4c_ ... ifications

the crs317
https://mikrotik.com/product/crs317_1g_ ... ifications

CRS312-4C+8XG-RM has separate QCA9531 CPU and Marvell-98DX8212 switch chip.
Here is the block diagram:
https://i.mt.lv/cdn/rb_files/CRS312-4Cp ... 104503.png

We will update the CRS312-4C+8XG documentation regarding that.

You could update the Specifications table by mentioning those 4 combo ports as well ...

Thanks a lot for posting the block diagram. I have assumed this will be a silent switch, but I can see 4 fans there. Are the fans on constantly or only under some severe load?

Another question I cannot answer from the current specs - while the 8 non-combo ports are N-Base-T (1,2.5,5 and 10G), are the 4 combo ports using the same PHY with N-Base-T or are they fixed to 10G (which is what would the wording in the data sheet suggest, but perhaps it's just being paranoid).