Hey,

I have a RB 1100AHx and I am somehow confused about the aggregate throughput I see on all ports.

Setup:

ether 1: internet uplink 100 MBit
ether 2: file server 100 MBit
ether 3-10: associated to interface "bridge1"

There is a PPPoE Server running on bridge1, dialup users connect using PPPoE.

Somehow it seems that the in/out traffic on bridge1 never exceeds 100 MBit.
I expected to see max. possible throughput > 100 MBit,
because it can originate from the internet and from our file server.

When user1 downloads with 80 MBit from internet
and user2 downloads with 80 MBit from file server
I should see 160 MBit throughput on bridge1 interface, right?

I have never observed this and in high load situations I also could not induce aggregate throughput to go above 100 MBit.

What could be the reason for this?

The bridge interface, is a software based interface, not hardware. So basically, any software processing has lower performance than hardware one. I don't know what the speed of the bridge could be, but definitely it will be less than any hardware interface.
If you can group your ports form 6 to 10 in the switch, it will be far better than grouping them under the bridge.

hmhm... I have never done that.
grouping under switch

I will try this ...