Thanks for this explanation. This makes a lot of sense and makes it easily understandable!Important thing to understand is what exactly gets offloaded from bridge to switch chip: it's passing frames between ports, attached to switch chip (typically they're either RJ45 or SFP ports, always consult block diagram of particular device), and which are members of same bridge. Additionally switch chip handles adding/stripping VLAN headers in case when port is untagged member of a particular VLAN.
However, anything related to router's IP stack (including vlan interfaces) is entirely processed by CPU (unless device is capable of L3HW offload).
So using bridge with single physical port doesn't allow any offload to hardware (untagged "VLAN" in this case doesn't need any VLAN tag manipulation and adding VLAN tag by switch chip actually means slightly more CPU processing due to use of vlan interface).
Let's evaluate it with e.g. the CCR1009 sfp-sfpplus1 interface. Would you use a bridge for Router-on-a-Stick configuration with multiple VLAN, or would you do it without a bridge?
I understand that the bridge won't gain any HW offload, but does it harm? Is it still best-practice to use a bridge for such a scenario?
Statistics: Posted by tobcon — Tue Jan 07, 2025 8:02 pm