MikroTik CRS328-24P-4S+RM Internal Overview
Inside the switch, we see the simplicity of design. It is effectively a metal box with two main sections. The top (rear of the switch) is a power supply covered by a black shroud. The bottom is the switch PCB.
The power supply itself is relatively large for a 500W model. Here is a view of the PSU without that black shroud on it:
For a sense of scale, here is a Supermicro SYS-1029P-WTRT 700/750W 80Plus Platinum server power supply sitting in front of the MikroTik 500W PSU. Note, the Supermicro PSU has the AC input (behind the PSU on the MikroTik) as well as a fan (to the right in this photo on the MikroTik) built-in.
450W of that 500W PSU is split into three 150W segments. Each of these 150W segments powers a MikroTik PSE-24 PoE/ PoE+ power distribution board.
Each of these power distribution boards is aligned to a set of 8x 1GbE ports.
Tracing the power distribution from the power supply to these PoE injection boards and finally to the ports allows us to see how MikroTik is building a switch with 450W of capacity with 150W per 8 ports.
While the vast majority of the switch goes to powering those 24 ports, there is a bit more going on. Here is what the block diagram looks like for the switch:
Again, we see MikroTik turn to a Marvell Prestera switch chip. This is the same chip that is used on the MikroTik CRS326-24G-2S+RM and the MikroTik CRS305-1G-4S+IN we reviewed. There is also a CRS328-4C-20S-4S+ model we have not reviewed that the company uses this chip on. We get an 800MHz single-core Arm chip for the management controller. As a quick aside here, we like that MikroTik is disclosing the switch chip solution inside their products. Many vendors in this space do not while it is a common practice in the higher-end segments. If there was ever an issue like the Intel Atom C2000 Series Bug one could figure out if their MikroTik is impacted (to our knowledge MikroTik never used the C2000 chips in the CRS line.) Many other vendors in the lower-cost switch space do not disclose what chips they use so one would have no idea that they are impacted if a silicon bug is found.
There is one other small feature we wanted to point out while looking at the inside of the switch, and that is a feature with fan headers. On the left side of the switch, there are two headers powering two PWM fans. On the right side of the switch, we have standard labeled 4-pin PWM fan headers that are empty.
These fan headers correspond to two openings for 1U fans on the side of the switch so MikroTik seems to have thought about people wanting to potentially try fan mods here.
You will notice that picture is labeled “Paint Job” and there is a good reason. The inside of the chassis took some paint as it was applied from the exterior. That is something you tend not to see as much of on higher quality switches. At the same time, it does not impact operation so it seems to be a small area of cost savings in the manufacturing process. You can certainly tell the difference between the CRS328-24P-4S+RM versus a $5000 or $1000 switch such as the Edgecore AS7712-32X 32x 100GbE Switch, but that is reasonable. This is a $379 list price switch.
One other item that you will have noticed is that the airflow is side to side instead of front to back or back to front. Many racks are not designed to handle that kind of airflow so we are going to caution our readers to ensure this will work for their racks. This is a cost-saving measure since MikroTik does not need to have two SKUs one for PSU to Port and one for Port to PSU airflow, but one needs to be aware of it.
Next, we are going to look at the management, power consumption, performance, and discuss our final thoughts.