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- switching decision - widely depends on the switch model. This block controls all the switching-related tasks, like host learning, packet forwarding, filtering, rate-limiting, VLAN tagging/untagging, mirroring, etc. Certain switch configurations can alter the packet flow;
- switch-cpu port - a special purpose switch port for communication between the main CPU and other switch ports. Note that the switch-cpu port does not show up anywhere on RouterOS except for the switch menu, none of the software-related configurations (e.g. interface-list) can be applied to this port. Packets that reach the CPU are automatically associated with the physical in-interface.
The hardware offloading, however, does not restrict a device to only hardware limited features, rather it is possible to take advantage of the hardware and software processing at the same time. This does require a profound understanding of how packets travel through the switch chip and when exactly they are passed to the main CPU.
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Switch features found in the "/interface/ethernet/switch" menu and its sub-menus, like ACL rules, mirroring, ingress/egress rate limiters, QoS, and L3HW (except inter-VLAN routing) may not rely on bridge hardware offloading. Therefore, they can potentially be applied to interfaces not configured within a hardware-offloaded bridge. |
Switch Forward
We will further discuss a packet flow when bridge hardware offloading is enabled and a packet is forwarded between two switched ports on a single switch chip. This is the most common and also the simplest example:
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