problem with vlan interfaces tagging/untagging in a simulated switch box

[Peter Jeremy]

Please don't top-post.

On 2012-Mar-05 13:30:36 +0330, h bagade <bagadeh at gmail.com> wrote:
>on layer 2 switch, ports doesn't have ip addresses and traffic comming
>from a vlan port is tagged and pass through trunk port. this means
>that in our freebsd box which plays the role of switch, no interfaces
>should have ip addresses.

OK.  Sorry, I misunderstood what you were trying to achieve.  I am
using FreeBSD as a router rather than a switch.  That said, I suspect
your problem is that you are misunderstanding how VLAN tagging is
applied.  If a packet flows through a vlan(4) device, the appropriate
tag is removed from incoming (from the network) packets and added to
outgoing (to the network) packets.  Packets flowing through normal
ethernet devies (your ethX) without also flowing through a vlan(4) are
not tagged (and so will appear in the default vlan as far as an
external switch is concerned).  Internally (ie as seen by bridge(4)
instances), packets are not tagged.

The following example diagram shows 3 distinct packet flows:
- packets tagged 5 in trunk1 and 6 in trunk0
- packets tagged 7 in trunk1 and 9 in trunk0
- packets tagged 8 in trunk0 and 10 in trunk2

                 +-- vlan5 --- bridge1 --- vlan6 --+
                 |                                 |
trunk1 --- eth1 -+-  vlan7 --- bridge2 --- vlan9 --+-- eth0 --- trunk0
                                                   |                  
                               bridge3 --- vlan8 --+
                                  |                 
             trunk2 -- eth2 --- vlan10

This would be configured as:
ifconfig vlan5 vlan 5 vlandev eth1
ifconfig vlan6 vlan 6 vlandev eth0
ifconfig vlan7 vlan 7 vlandev eth1
ifconfig vlan8 vlan 8 vlandev eth0
ifconfig vlan9 vlan 9 vlandev eth0
ifconfig vlan10 vlan 10 vlandev eth2
ifconfig bridge1 addm vlan5 addm vlan6
ifconfig bridge2 addm vlan7 addm vlan9
ifconfig bridge3 addm vlan8 addm vlan10

-- 
Peter Jeremy
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