Re: [B.A.T.M.A.N.] Questions arised while iplementing NetJSON

[Sven Eckelmann <sven@narfation.org>]

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On Thursday 08 October 2015 09:25:55 Germano Massullo wrote:
> I have some questions about JSONDoc created by command <<batadv-vis
> --format=jsondoc>>
> In jsondoc_commented file there are a few addresses that are not shown
> in ip_addr file. I commented them using
> 
>     # non existing in file ip_addr
> 
> What are exactly the addresses in "clients"? What do they represent?
> The procedure I followed to create the interfaces is available at [1]

These are "clients" from the local translation table. It is like a switch
lookup table but in this case for "client" which are "above" the bat0
device.


---------------------------------------
|   bridge (mac 00:11:22:33:44:55)    |           
|                                     |
| bat0                        eth0    |
|   |                          |      |
----|--------------------------|-------
    |                          |
----|------                    |
| adhoc0  |                    |
----|------                   /|\
    |                        / | \
 ~~~~~~~~~~                 /  |  \
(mesh cloud)               /   |   \
 ~~~~~~~~~~           -----    |    -----------
                     /         |               \
 --------------------    --------------------   --------------------
 | device 1         |    | device 2         |   | device 3         |
 | mac:             |    | mac:             |   | mac:             |
 | 02:ba:de:af:fe:01|    | 02:ba:de:af:fe:02|   | 02:ba:de:af:fe:03|
 --------------------    --------------------   --------------------

So the device below bat0 is adhoc0. The devices "above" bat0 (from which it
gets non-batman-adv traffic) are the bridge and device1, device2, device3.

So the clients should contain:

 * 00:11:22:33:44:55
 * 02:ba:de:af:fe:01
 * 02:ba:de:af:fe:02
 * 02:ba:de:af:fe:03

You can check this also with the command: batctl tl

There is also a global translation table which you can get via: batctl tg.

But now you may say: "hey, I don't use a bridge on top of bat0 - there are no 
other devices above bat0". That may be correct but batman-adv can only find 
these devices by looking at packets coming from "above" and just has to accept 
everything which is coming from there (even forged stuff). But don't forget 
the other source of addresses in there is the multicast table (otherwise the 
multicast optimization from Linus doesn't work). So I would guess that this is 
the result of the other entries.

I think Antonio and Linus can help you to understand it better when you give 
them the output of `batctl tl` + `batctl tg` + `ip maddr show dev bat0`. But 
here is my interpretation:

33:33:00:00:00:01 - (mcast) IPv6 neighbor discovery protocol
33:33:ff:xx:xx:xx - (mcast) some other IPv6 multicast
01:00:5e:00:00:01 - (mcast) IP multicast

Kind regards,
	Sven

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