I have been testing and can not find difference between those configurations.
I prepare a switch using both aproaches and find that behaviour is same, looking packets with wireshark.
I was expecting that bridge mode generate more arp traffic over the network since it would behave similar to a hub but it didn`t.
Can some one go a littel deeper on this ?
After get it clear I will need to set rapid spanning tree.
Regards.
Leandro.

Ports in same switch chip in master/slave mode won't use CPU to reach wirespeed, as everything is managed by the switch chip.

Ports in a bridge = switch by software, uses router CPU. Ports in a bridge can be filtered by firewall.

It also impacts Fastpath operation. Have a look at this presentation for more details.

Adding to the information Pukkita gave-

The hardware switch (master/slave) doesn't do spanning tree (as far as I know - I could be wrong)
You can't use ip firewall / bridge firewall rules to filter switch traffic.
Switch can only forward at layer2 between ports using the same switch chip. On a 2011-series routerboard, for instance, ether1-ether5 are switch1 and ether6-ether10 are switch2. You must use CPU bridge to link these two switches into a single broadcast domain. (wire speed between 2-5, and wire speed between 6-10, but cpu speed between 3 and 9, for instance). WiFi must be bridged with CPU bridge.

In a nutshell = hardware switch is the fastest, but has the fewest features.

Thanks !!! your replyes were very usefull.
Leandro.

Thanks Zerobyte! Very helpful

are vlans proccesed in the cpu or in the switch chip directly ?

are vlans proccesed in the cpu or in the switch chip directly ?

VLANs can be handled at both the switch chip and the CPU. The switch chips are VLAN-aware so you can support multiple logical switches on a single piece of hardware. To route between VLANs, though, you have to make the CPU aware of the VLANs and set up an address on each VLAN at the CPU.