Re: [B.A.T.M.A.N.] lost connection to a client / Q: transglobal-table

Antonio Quartulli
2013-11-01T14:39:03Z

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On Fri, Nov 01, 2013 at 03:33:05PM +0100, Bastian Bittorf wrote:
> * Antonio Quartulli <antonio@meshcoding.com> [01.11.2013 13:53]:
> > > here the transglobal-table in the master, my laptop is '00:21:6a:32:7c:1c'
> >
> > what is master?
>
> the node which has internet connectitvity / default gateway.
>
> >
> > > the interesting thing is, that my laptop seems to be reachable via
> > > *:02:22 and *:00:13 - the 2nd entry has no hash (?), but 'batctl t 00:21:6a:32:7c:1c'
> > > outputs *:00:13 as originator. from the topology, it is impossible to be
> > > near this node, so no roaming can happen AND i can see on my laptop,
> > > that there was no roaming. the situation recovers without interaction after some
> > > minutes. the transglobal table does not change, but 'batctl t 00:21:6a:32:7c:1c'
> > > outputs the correct *:02:22
> > >
> >
> > Here[1] you have an explanation about the translation table output.
>
> thanks, this help: so [.W.] means:
> "this client is connected to the node through a wireless device"

It also explains why you have more than one entry for the same client and why.

>
> Client (TTVN) Originator (Curr TTVN) (CRC ) Flags
> * 00:21:6a:32:7c:1c ( 4) via 02:00:ca:b1:02:22 ( 5) (0x6456) * [.W.]
> + 00:21:6a:32:7c:1c ( 5) via 02:00:ca:b1:00:13 ( 5) [.W.]
>
> but i can be sure, that may laptop "00:21:6a:32:7c:1c" was never connected to '02:00:ca:b1:00:13'.
> both nodes are not connected via cable and are nodes in hybrid-mode (ap+adhoc).
> no special tricks, 'only' macvlan. BLA2 is active on all nodes.
>
> the again: why does batman-adv think, that the client (my laptop) is/was
> reachable over 02:00:ca:b1:00:13 - the laptop was never there? a hash-collision?

No. This happens when bat0 on one node and bat0 on the other are bridged
together. The common scenario for this is that you have the two nodes connected
to an Ethernet switch and you have bat0 bridged into this LAN. At this point the
"two bat0s" will get in touch with each other. Like the first picture in this
page[1].

The "only" macvlan thing is probably something we should try to investigate
further :-)
You are the first reporting strange issues like this and the fact that this
happens quite often means that there is something in the network setup that is
triggering this problem.

Do you mind explaining a bit more in details how you structured the node? (which
interface is bridged with what, where macvlan is connected).

Can you also provide the output of "batctl bbt" ?

>
> what i also see now:
> a laptop is connected via wifi to NodeA, but i ask the 'transglobal'
> table, batman-adv says it is on another location and 'batctl tr $lapop'
> also works. explaining it:
>
> NodeA = 192.168.99.1/16 ~~~ Laptop with 192.168.222.51/16
>
> (air)
>
> NodeB = 192.168.222.1/16
>
> The Laptop is connected to Node A, but has an IP from Node B.
> batman-adv thinks that the Laptop is on NodeB, but in fact it
> is on NodeA. Why is this? On Node A 'wlan0' is bridged to bat0.
>

I guess you roamed from NodeB to NodeA ? Is the entry in the global table
followed by a "R"

Cheers,

[1] http://www.open-mesh.org/projects/batman-adv/wiki/Bridge-loop-avoidance-II

--
Antonio Quartulli

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