Ethernet switch device driver

Question

Hi

We're designing a network device based around SoC, which contains MIPS core and 5-ports switch core, connected to the CPU via internal MII port.

Device driver provided by a chip vendor represents 5-port switch as a single inteface from the OS perspective; the driver also supports VLAN and currently it splits 5 ports in two VLAN groups. On evaluation board this scheme somehow works, with a combination of software bridge, software vlans and firewall rules.

Homwever we are planning to make use of external 24-ports switch, and it will be connected to the SoC via two ports of the internal switch, and those two ports will serve as WAN and LAN ports respectively and should be able to have IP addresses, so our design will look different from a reference design. Therefore I see no other way rather then make these five internal ports look as distinct interfaces form the point of view of the OS.

Then it would allow assign these interface WAN and LAN addresses, and put interfaces of the external switch in corresponding VLAN groups.

Would this mechanism do you think work or not? And second, if I make these distinct interfaces, will it force any switching to be done in software rather then in hardware?

Thanks.

Answer 1

From Linux kernel point of view you can do this, i.e. create a few network device drivers which will be connected to the same physical device, i.e. your switch. However, the way to disable switching in HW is very... well, HW dependent. Check your switch documentation.