[Bridge] received packet with own address as source address

Nikolay Datchev nik at varna.net
Mon Jan 19 05:55:02 PST 2004


just my $0.02:

ethertap interfaces has fake mac addresses, generated somehow by the
tun/tap driver, and they are same on both sides in your case. Don't know
why.

-- Nikolay Datchev

On Fri, 16 Jan 2004, Christopher S. Aker wrote:

> Hello,
>
> I manage a number of servers all running 2.4 (same problem exists with 2.6).  My
> problem is that since a few bridge versions ago, I've had to modify
> net/bridge/br_fdb.c in the br_fdb_insert() function -- to get rid of the checks
> that produce this error:
>
> Jan 16 10:35:31 host15 kernel: tap_0: received packet with  own address as source
> address
> Jan 16 10:35:33 host15 kernel: tap_0: received packet with  own address as source
> address
>
> My specific setup is: br0 assigned an IP, with eth0 added to the bridge with no
> IP.  I create tap devices, assign them no IP address but a unique MAC.  On the
> other end of each tap device is an UML virtual machine's eth0.   My machines are
> SuperMicro 6013 dual xeon boxes with e1000, and a 5012 box with e100 NICs.  I
> don't believe this is a checksum issue raised a while back.  STP is off.  Settings
> for setfd and sethello make no difference.   As soon as UML brings up its eth0
> interface, the messages appear.
>
> I'm really not a kernel hacker, but I was able to look at previous versions of the
> file and more or less just comment out the "if (unlikely(fdb->is_local))"
> statement.  This is what I've been using for the past few months.  It seems to
> work as it did before this new check was put in place.  But, I still have a
> problem where showmacs displays this for each tap interface:
>
>   2     fe:fd:45:38:ad:f1       no                 4.88
>   2     fe:fd:45:38:ad:f1       yes                0.00
>
> Two entries for the same interface -- a local, non-expiring fdb entry, and a
> non-local expiring fdb entry.  Once the non-local fdb entry times out, the tap
> loses connectivity from the world.  If I log into the host machine locally and
> ping an IP on the TAP interface, it comes back alive.  Same goes for logging into
> the UML's console and pinging the host.  I've had this problem even with the older
> bridge code.  I think all this is related to the real problem.  Looks like
> something isn't detecting traffic as local, or perhaps it needs special handling
> for this case?
>
> Others have been using the identical bridge setup, minus the e100/1000 cards, and
> haven't reported either of these problems.  Any advice would be appreciated.
>
> Regards,
> -Chris
>
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