Community discussions

MikroTik App
 
lrmax
just joined
Topic Author
Posts: 1
Joined: Wed Mar 08, 2023 6:50 pm

Bridging ProfiNET / other ethertypes

Wed Mar 08, 2023 6:57 pm

We have a lab setup where we want to have a bridge for profinet. However, I don't think this issue is related to profinet itself, but being an uncommon ethertype.

In short, profinet packets are ethernet frames with ethertype set to 0x8892. Payload doesn't really matter since it shouldn't be handled by the bridge.

The setup we have is a RouterBoard hEX where two ports are bridged. Preferrably bridged to a a vlan on a third port too later.

When I send profinet packets on one of the ports, I expect them to end up in the other port, given that the destination mac address on the packet is correct, but it doesn't.

I can correctly see the frames when enabling the packet sniffer on the port itself as incoming packets, but I can not see the frames when enabling the packet sniffer on the bridge interface. There I only see the IP frames and some others. Also, I can not see the frames being outputted on the second port.

I assume there is a packet filter filtering unknown ethertypes somewhere, or some option I need to change.

Where do I control which ethertypes that can be forwarded over a bridge?
 
tdw
Forum Guru
Forum Guru
Posts: 1843
Joined: Sat May 05, 2018 11:55 am

Re: Bridging ProfiNET / other ethertypes

Wed Mar 08, 2023 10:24 pm

There is no packet filtering by default. When a bridge has STP enabled it conforms to 802.1D and does not forward packets destined for 01:80:C2:00:00:0X addresses, per the specification. In some cases it is desireable to forward these which can be accomplished by setting protocol-mode=none.

Packets traversing a bridge may be manipulated by the bridge firewall unless hardware-offloading is enabled, in which case switch rules should be used.

Packet sniffing on the bridge itself, i.e. the switch chip to CPU interface, will not yield any results when hardware-offloading is enabled for unicast packets between ports where the destination address has be learnt by the switch FDB, see https://help.mikrotik.com/docs/display/ ... adedPacket

Who is online

Users browsing this forum: Bing [Bot] and 57 guests