tunneling L2 tagged traffic over IP

[Victor Sudakov]

Nikos Vassiliadis wrote:
> > I have two interfaces in a bridge:
> >
> > # ifconfig bridge0
> > bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
> >          ether 02:d7:d7:0d:ff:00
> >          inet 10.14.133.20 netmask 0xffffffc0 broadcast 10.14.133.63
> >          nd6 options=9<PERFORMNUD,IFDISABLED>
> >          id 00:00:00:00:00:00 priority 61440 hellotime 2 fwddelay 15
> >          maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
> >          root id 00:00:00:00:00:00 priority 61440 ifcost 0 port 0
> >          member: vr0 flags=1c3<LEARNING,DISCOVER,AUTOEDGE,PTP,AUTOPTP>
> >                  ifmaxaddr 0 port 6 priority 128 path cost 200000
> >          member: tap0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> >                  ifmaxaddr 0 port 11 priority 128 path cost 2000000
> > #
> >
> > "tcpdump -i vr0 stp" sees incoming STP traffic while "tcpdump -i tap0 stp"
> > sees none no matter if net.link.bridge.pfil_onlyip is "1" or "0".
> >
> > I see however some IP6, IPX (!) and CDP frames.
> >
> 
> STP frames are not forwarded. As well as other special frames:
> 
> >                 /*
> >                  * Check if its a reserved multicast address, any address
> >                  * listed in 802.1D section 7.12.6 may not be forwarded by the
> >                  * bridge.
> >                  * This is currently 01-80-C2-00-00-00 to 01-80-C2-00-00-0F
> >                  */
> 
> FreeBSD does that unconditionally. That could probably be a tunable:)
> If you have a "simple" ethernet bridge (without STP) you should
> forward STP frames. I guess a patch would be welcome!

That's from src/sys/net/if_bridge.c

Fine. Maybe there are other ways to tunnel Ethernet without relying on
if_bridge ?

Besides, I also need to tunnel 802.1q tagged frames, so if_bridge is
unsuitable anyway.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru