Re: [B.A.T.M.A.N.] Can b.a.t.m.a.n. be configured to ARP for unknown clients?

["Linus Lüssing" <linus.luessing@c0d3.blue>]

And one more question: How are the IPv4 addresses assigned? Static
configuration or via DHCP? If the latter, what is your current
lease timeout and would it be an option to lower it?

Regards, Linus


On Fri, Dec 29, 2017 at 05:01:23PM +0000, Robert Bates wrote:
> Hello,
> 
> Is it possible to have b.a.t.m.a.n. ARP if packets are received at bat0 for a client which has been removed/deleted due to timeout, and is therefore no longer in the translation tables?
> 
> In one customer application of a product of ours (a mesh AP we've licensed from another vendor/developer, which is based on openWRT/b.a.t.m.a.n.), we are being adversely affected by the 10 minute inactivity timer on transtable_local.   The clients in this customer's network/application are stationary devices which basically do not speak unless spoken to (e.g. when they are polled for data).  They are periodically polled by a management platform, using an upper layer protocol running over TCP.  The problem is that this customer's polling cycle time is variable, and occasionally it is taking longer than 10 minutes between successive polls of a given client/device.  When this happens, that client is of course removed from transtable_local, and transtable_global on the other nodes in the mesh.  Meanwhile, the polling/management platform has a very long ARP cache life, so it never ARPs (and apparently it is not possible on this platform to have the customer implement dynamic, rather than static ARP table entries, in which it would ARP upon polling failure).  So once we get into this state, polls to this client device which has dropped out of the mesh are not possible, and their management platform throws alarms, etc.  To bring it back in service at that point requires an ARP, which the customer is manually triggering with a ping, whenever one of these "outages" occurs.
> 
> We know that the transtable_local inactivity/removal timer value can be extended, and we will probably do that, but we would also like to know if it is possible to have b.a.t.m.a.n. ARP for the removed client in this case.  We prefer this approach, rather than arbitrarily changing the tt_local timer to some value which may not work well in some other customer's network/application.  I know that there is a statistically valid underlying assumption with this 10 minute inactivity timer on transtable_local, that clients will typically be "chatty".  But again, that is not the case in this application, which is a very common one in the industry in which we operate, where clients are very often fixed devices which only respond to explicit queries or commands.  This is a new product and protocol for us, and this could beg the question of whether or not b.a.t.man.-based meshing is the right solution in this type of application.  We believe it can be; it would just be helpful if we can configure it to ARP in this type of scenario.
> 
> Can you please comment on how this might be possible (config or otherwise)?
> 
> Thanks very much,
> Robert Bates
> 
> IMPORTANT NOTICE:  This communication, including any attachments, is the property of FreeWave Technologies, Inc. and may contain proprietary, confidential, or privileged information. Unauthorized use or disclosure of this communication is strictly prohibited and may be unlawful. Information contained herein may be subject to a Proprietary Information / Non-Disclosure Agreement and shall be maintained in confidence and not disclosed to third parties without the written consent of FreeWave Technologies, Inc. If you have received this communication in error, please immediately notify the sender and destroy all copies of the communication and any attachments.