Re: [B.A.T.M.A.N.] Unterstanding gateway-mode - why do nodes have a "sticky" gateway

[NicoEchániz <nicoechaniz@altermundi.net>]

On 01/03/2013 12:14 PM, Marek Lindner wrote:
> On Thursday, January 03, 2013 23:01:07 Jan Lühr wrote:
>>> Ah! You failed to mention this part in your initial email.
>>>
>>> The behavior is easily explained: batman-adv does not switch gateway
>>> whenever a new gateway is found (even if it is a better gateway) unless
>>> the selection class is on fast or late switching.
>>
>> It is. - Sorry, forgot to mention:
>> Freifunk-b0487acb2d58:~# batctl gw_mode
>> client (selection class: 1)
>>
>> => 1 -> fast connection consider the gateway's advertised  throughput as
>> well as the link quality towards the gateway
> 
> You did mention you were using selection class 1. I was referring to your test 
> in which you turn on/off your best gateway. As I explained in my previous 
> mail: batman-adv does not switch the gateway once it has chosen a gateway 
> unless you select fast or late switching as selection class. Selection class 1 
> does not fall into this category which means a gateway reselection only 
> happens if the currently selected gateway disappears.


Marek, could you please clarify this?

From the man page I don't see an option that would behave as Jan (and I) seem to be expecting it to work. That is: switch to a better gateway - with more bandwidth and comparable link quality - when it's available.


gw_mode|gw [off|client|server] [sel_class|bandwidth]
[...]
              If the node is a gateway client the parameter will decide which
              criterias to consider when the batman-adv module has to choose
              between different internet connections announced by the afore-
              mentioned servers.
                        default: 20 -> late switch (TQ 20)
                       examples:  1 -> fast connection
                                       consider the gateway's advertised
                                       throughput as well as the link quality
                                       towards the gateway
                                 2  -> stable connection
                                       chooses the gateway with the best link
                                       quality and stick with it (ignore the
                                       advertised throughput)
                                 3  -> fast switch connection
                                       chooses the gateway with the best link
                                       quality but switches to another gateway
                                       as soon as a better one is found
                                 XX -> late switch connection
                                       chooses the gateway with the best link
                                       quality but switches to another gateway
                                       as soon as a better one is found which
                                       is at least XX TQ better than the cur-
                                       rently selected gateway (XX has to be a
                                       number between 3 and 256).


Would mode 3 accomplish this fast switching? It doesn't mention if this mode will consider advertised throughput or not; only selection class 1 mentions throughput.


--
NicoEchániz