Hello Simon,
Simon Wunderlich sw@simonwunderlich.de schrieb am 19.02.2016 16:06:03:
- Although having the patch for 1. applied, the backbone gateways
send
claim frames for the devices of their own backbone in rare cases from
time
to time. I could send a patch for this as it is rather easy to check
with
the help of the local tt table (batadv_is_my_client) if it is
reasonable
to send a claim frame for these devices. Again, this patch looks more
like
a workaround to me as I also cannot explain what really triggers the generation of these claim frames.
I don't think this is the right way to solve it - if a client has roamed
to
another device in the mesh, a gateway MUST send a claim. However batadv_is_my_client would probably return true, suggesting that the
client is
local although it is not local anymore.
The problem probably needs to be fixed somewhere else.
- I see again in rare cases looping multicasts for traffic
mesh->backbone->mesh. If I look at the bla debug messages in these
cases I
see, that a backbone gw holding the claim for the source of the
multicast
frame thinks that the client belonging to the source address has
"roamed"
from another mesh node into the backbone network although it didn't.
From
this I conclude that another backbone gw has forwarded the multicast
into
the backbone although it shoudn't have done this (having found no
claim
for the client or erroneously also holding a claim). In this case the backbone gateways seem to be out-of-sync about the actual claim status
for
that client. This effect only lasts a very short time, as the gateway which found the "roaming" client unclaims it and within a few
milliseconds
(depending on the traffic generated by the client) another backbone gw
(or
the same) claims the client again. Of course then the looping of the multicast traffic from the client stops. In my case the sender of the multicast was the bridge interface br0 of a remote mesh node itself.
The
bat0 softinterface was added to that bridge. The looping multicast
then
gave me a "bat0: received packet with own address as source address" message. Furthermore that bat0 interface sent a claim frame for the
mac of
the own bridge (whch is obvious as bat0 received a message from the
mesh
with a mac address not claimed yet....). This claim frame then
produces
another "bat0: received packet ..." message. I currently have no workaround for this 3rd issue as all I can image
to
prevent this will break the "roaming client" scenario for bla. I could even live with this problem as it happens quite seldomly and as it is "self-healing", but it tells my that there might be a sync issue. Do
you
think that my 1st and 2nd point could also relate to the same problem? In the meantime I looked through the code for hours but I am not able
to
find something that could explain the observed problem.
Hmm ... that sounds strange. I don't know if this is related to the your first two points since we are talking about multicast here and the other points were about unicast.
In the meantime after further attempts to debug this I can say that 2. and 3. are somehow related to each other as both seem to happen at the same time. I cannot syncronize the debug messages as they are recorded by two different nodes (a backbone gw A and a normal node B) but it looks as if I first get a packet sent by B which is forwarded into the mesh by gw A again leading to
an unclaim of B (although B hasn't roamed to the backbone). After that A has added B to the local TT. Then A receives a unicast packet from B via the mesh. After this packet I see different other unicast packets sent by devices from the local backbone network of A coming via the bat0 interface erroneously. These packets trigger the generation of claim frames (as described in 2.).
I think the main question here is - if the packet came from the mesh,
why
wasn't there a claim frame?
Maybe two questions could help:
- does this happen in the first minutes after starting/restarting the
mesh?
There is some initial time for bla gateway nodes to detect each other, although this should happen quite fast.
I am aware that this might be a little bit unstable after establishing the mesh. But this normally happens after some minutes of successfull operation of the system (in the order of 10 minutes approximately).
- Do you have some unusual high amount of broadcast/multicast (e.g.
streaming, fieldbus protocol, etc)?
No, only normal IPv4 stuff and sometimes some ARPs. I use normal IPv4 communication to the webinterfaces of my nodes and some normal pings (a packet a second). The nodes itself have IPv6 enabled although I don't use IPv6 but only IPv4 addressing. The multicasts in question are for destination mac 33:33:00:00:00:01 (IPv6) and are sent each 10 seconds by the IPv6 Linux stack.
What might help is to get dumps from the hard interface as well as the
bat0
soft interface and check the corresponding packets when this
problemhappens.
Not sure if this helps and how easy it is to capture dumps ...
Cheers, Simon[Anhang "signature.asc" gelöscht von Andreas Pape/Phoenix
Contact]
.................................................................. PHOENIX CONTACT ELECTRONICS GmbH
Sitz der Gesellschaft / registered office of the company: 31812 Bad Pyrmont USt-Id-Nr.: DE811742156 Amtsgericht Hannover HRB 100528 / district court Hannover HRB 100528 Geschäftsführer / Executive Board: Roland Bent, Dr. Martin Heubeck ___________________________________________________________________ Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren, jegliche anderweitige Verwendung sowie die unbefugte Weitergabe dieser Mail ist nicht gestattet. ---------------------------------------------------------------------------------------------------- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure, distribution or other use of the material or parts thereof is strictly forbidden. ___________________________________________________________________