Hello
I was reading the docs about the RB1200.
In the userguide, link is : http://routerboard.com/pdf/308/rb1200ug.pdf
I see in the latest page a scheme of the hardware.
Port 1 to 5 can be used as a switch (wire-speed I think)
6,7,8 direct connected to the CPU
9,10 are via the PCIe BUS.
OK.
When using as a Routed port, what is the difference using the port direct connected to the CPU or the ones via the PCIe bus?
I just want to understand.
Thank you
+1 for this info!
I have noticed a strong degrade in performance on ports 9,10
Using these ports the latency is variable from 0 to 30ms
I’ve opened a support ticket
The response of Mikrotik was this:
Ports ether9 and ether10 on RB1200 are connected through PCI-E controller.
Currently these ports have performance limitations to keep overall operation of
router stable. Because of these limitations latency has increased.
It could be fixed in future RouterOS versions.
an follows with:
The problem could be fixed if better driver will be available for RouterOS version 6.
Ports 9&10 WILL cause performance issues (low throughput and variable latency) used in any configuration - don’t use them - other ports work just fine
Well… the question is:
Why there is a diagram and they says that the port are working badly ?
Why they included them? 
Pity that such information is not released from Mikrotik. We’ll find out only when there is a problem and we have the same configuration