bridged tap interfaces with stp

[Andrew Thompson]

On Mon, Sep 22, 2008 at 05:00:59PM +0300, Sergey Listopad wrote:
> Hi!
> 
> I am playing with bridge(4) stp feature.
> 
> there are 2 boxes with 7.0-RELEASE-p4.
> 
>       rt1                                                rt2
>  ___________                                 ___________
> |            ____|                               |____            |
> |           |tap1| ------------------------|tap1|          |
> |                   |                               |                   |
> |           |tap2|-------------------------|tap2|          |
> |___________|                               |___________|
> 
> rt1 connected to rt2 with 2 openvpn L2 links (tap).
> 
> tap1 bridged with tap2 on both routers.
> 
> rt1# ifconfig bridge0
> bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>        ether 56:8d:35:75:ee:3f
>        inet 3.3.3.1 netmask 0xffffff00 broadcast 3.3.3.255
>        id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
>        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
>        root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
>        member: tap2 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>        member: tap1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> 
> rt2# ifconfig bridge0
> bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>        ether 3a:af:9d:0f:c1:b9
>        inet 3.3.3.2 netmask 0xffffff00 broadcast 3.3.3.255
>        id 00:00:00:00:00:00 priority 16384 hellotime 2 fwddelay 15
>        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
>        root id 00:00:00:00:00:00 priority 16384 ifcost 0 port 0
>        member: tap2 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>        member: tap1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
> 
> rt1# ping 3.3.3.2
> PING 3.3.3.2 (3.3.3.2): 56 data bytes
> 64 bytes from 3.3.3.2: icmp_seq=0 ttl=64 time=8.144 ms
> 64 bytes from 3.3.3.2: icmp_seq=1 ttl=64 time=4.313 ms
> 64 bytes from 3.3.3.2: icmp_seq=2 ttl=64 time=4.421 ms
> ...
> all works while broadcast
> 
> Then I'd try to enable stp on bridge0 interfaces for automatic disable
> one of redundant links (tap1/tap2).
> rt1# ifconfig bridge0 stp tap1 stp tap2
> rt1# ifconfig bridge0
> bridge0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST>
> metric 0 mtu 1500
>        ether 56:8d:35:75:ee:3f
>        inet 3.3.3.1 netmask 0xffffff00 broadcast 3.3.3.255
>        id 00:1c:c0:39:d6:b9 priority 32768 hellotime 2 fwddelay 15
>        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
>        root id 00:1c:c0:39:d6:b9 priority 32768 ifcost 0 port 0
>        member: tap2 flags=147<LEARNING,DISCOVER,STP,AUTOEDGE,AUTOPTP>
>                port 12 priority 128 path cost 2000000 proto rstp
>                role disabled state discarding
>        member: tap1 flags=147<LEARNING,DISCOVER,STP,AUTOEDGE,AUTOPTP>
>                port 16 priority 128 path cost 2000000 proto rstp
>                role disabled state discarding
> 
> rt2# ifconfig bridge0 stp tap1 stp tap2
> rt2# ifconfig bridge0
> bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
>        ether 3a:af:9d:0f:c1:b9
>        inet 3.3.3.2 netmask 0xffffff00 broadcast 3.3.3.255
>        id 00:1c:c0:39:d6:ad priority 16384 hellotime 2 fwddelay 15
>        maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
>        root id 00:1c:c0:39:d6:ad priority 16384 ifcost 0 port 0
>        member: tap2 flags=147<LEARNING,DISCOVER,STP,AUTOEDGE,AUTOPTP>
>                port 9 priority 128 path cost 2000000 proto rstp
>                role disabled state discarding
>        member: tap1 flags=147<LEARNING,DISCOVER,STP,AUTOEDGE,AUTOPTP>
>                port 8 priority 128 path cost 2000000 proto rstp
>                role disabled state discarding
> 
> But when stp is enabled, it blocks all bridge members, and bridge stop working.
> 
> May be I am misunderstand something with stp?
> At all it is possible to use bridge(4) stp with tap(4)?

This is because tap(4) does not have a media attachment, the spanning
tree code uses this to check if there is a link and obtain the duplex
(see bstp_ifupdstatus). Im not sure what the answer is, maybe ignore
this for pseudo interfaces.


Andrew