I was wondering on how CAPsMAN implemented the tunneling from non-forwarding cAPs to the CAPsMAN router, and investigating a packet capture, I found the cAP tunneling it’s data in ethernet frames with the protocol number 0x88bc. This isn’t an official protocol, nor is there any info on the protocol format. So I was wondering if either Mikrotik or someone else could at least comment on the overall structure. I already suspect that it’s simply a kind of Ethernet-in-Ethernet encapsulation.
I’d really like to hear some implementation details. Will it be possible to create virtual interfaces using this tunneling protocol in the future? It would certainly be useful for point-to-point (wireless) links.
On a side note: the protocol number 0x88bc might colide with the new-ish “ethernet for plant automation” protocol (EPA).
I noticed this too when looking at bridge traffic using the torch tool. There is 0x88bb and 0x88bc. The former is documented as LWAPP but Mikrotik might do their own thing there. I haven’t looked at any of them in Wireshark.
http://www.networksorcery.com/enp/protocol/lwapp.htm (0x88bb)
http://www.networksorcery.com/enp/rfc/rfc5412.txt
I’ll add that with the CRS3xx series switches you can use this to prioritise non-local-forward CAPSMAN traffic using an ACL rule. On one CRS354 switch I have:
/interface ethernet switch rule
add comment="Prioritise CAPSMAN PCP3" mac-protocol=0x88BB new-vlan-priority=3 \
ports="ether25,ether34,ether26,ether27,ether28,ether29,ether30,ether32,ether\
33,ether31,ether9" switch=switch1
add comment="Prioritise CAPSMAN PCP3" mac-protocol=0x88BC new-vlan-priority=3 \
ports="ether25,ether34,ether26,ether27,ether28,ether29,ether30,ether32,ether\
33,ether31,ether9" switch=switch1
All the interfaces listed have a CAPMANs AP and one is the CAPSMAN controller where all the traffic originates from. All going well the CAPSMAN frames will get priority on this switch!