Andrew Thompson wrote:
On Mon, Oct 16, 2006 at 12:15:13PM +0200, Jon Otterholm wrote:
Hi.

I have a bridge setup with a number of vlan IF's as members. After a while traffic destined for one member IF are sent to all member IF's.

From man if_bridge:

    A bridge works like a hub, forwarding traffic from one interface to
    another.  Multicast and broadcast packets are always forwarded to all
interfaces that are part of the bridge. For unicast traffic, the bridge learns which MAC addresses are associated with which interfaces and will
    forward the traffic selectively.

Has anyone else got this problem? How do I debug this?


You should run 'ifconfig bridge0 addr' to print out the forwarding
table, check if the mac address is listed on the correct port.


cheers,
Andrew
They are listed on the correct port but when I read man if_bridge I get
confused:

From man if_bridge:

discover interface
            Mark an interface as a ``discovering'' interface.  When the
            bridge has no address cache entry (either dynamic or
static) for
            the destination address of a packet, the bridge will
forward the
            packet to all member interfaces marked as ``discovering''.
This
            is the default for all interfaces added to a bridge.

Ie if my router doesnt know where to send the traffic all IF's with
discover enabled gets the traffic?

    -discover interface
            Clear the ``discovering'' attribute on a member interface.  For
            packets without the ``discovering'' attribute, the only packets
            forwarded on the interface are broadcast or multicast
packets and
            packets for which the destination address is known to be on the
            interface's segment.

If i set this on customer IF's it allmost works.

    learn interface
            Mark an interface as a ``learning'' interface.  When a packet
            arrives on such an interface, the source address of the
packet is
            entered into the address cache as being a destination
address on
            the interface's segment.  This is the default for all
interfaces
            added to a bridge.

    -learn interface
            Clear the ``learning'' attribute on a member interface.


As I understand this: I would be able to set "-discover" and "learn" on
all member IF's and everything would work. Unicast traffic with non
known destination would not travel to wrong IF's and the bridge fdb
would be updated with new customer mac's. This is almost the case - but
sometimes customers connection fails because the bridge fdb doesn't get
updated.

It seems that when a customer connects (ie starts his computer) with no
active DHCP-lease and the client sends out a DHCPREQUEST (broadcast) it
works like a charm until the bridge fdb entry expires. This could be
solved by setting timeout to 0 - but then I would get a polluted fdb.
For most customers it works all the time but for some it stops working
when the fdb entry expires.

I would like to know how the "learn"-function works and why it doesn't
work with unicast traffic.

/Jon

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