OSPF and mass route deletion

[Gruber Gerold]

Am 18.07.2015 um 10:54 schrieb Andrew:
> 18.07.2015 00:36, Ondrej Zajicek пишет:
>> On Tue, Jul 14, 2015 at 10:20:22AM +0300, Andrew wrote:
>>> When routes are deleted (for ex., terminating a lot of PPP tunnels
>>> for some
>>> reason in same time), it seems like each removed route is sent into
>>> separate
>>> OSPF packet that causes troubles with OSPF in some cases (for ex.,
>>> there's
>>> troubles with old quagga).
>>>
>>> Is there a possibility to add some rate-limiting (for ex., limit to 10
>>> messages per second), and aggregate separate 'route deleted' messages
>>> to one
>>> packet?
>> AFAIK, multiple flush LSAs can be packed to one LSA when flushed together
>> (i.e. the routes are deleted together), but there is no time-limit. If
>> these routes are deleted as separate (but immediate) events, then it is
>> possible that the OSPF packet with just one flushed LSA  is sent before
>> waiting for next route delete (and therefore next flushed LSA.
>>
> Maybe it'll be good to add some delay (for ex., 10ms) before flush LSA
> will be sent?
please allow me to quote in this context:
Am 08.06.2015 um 13:18 schrieb Ondrej Zajicek:
> On Mon, Jun 08, 2015 at 12:36:07PM +0200, Gruber Gerold wrote:
>> please allow me to add the pointer to the also wished "noise
>> suppression" in OSPF, where a delay between appearance or disappearance
>> of a route and it's propagation to the neighbours would also improve the
>> stability of the landscape and lower the "noise" caused by flapping
>> routes. (Cisco boxes behave this way, from our observations.)
>
> Hi
>
> This is AFAIK fixed in 1.5.0 - LSAs are originated at most once per
> MinLSInterval (5 s).
>

So if there is a "time trigger" for sending LSAs: should it not be
possible to filter (in the sense drop vanish/reappear pairs) or
aggregate multiple changes into one LSA message, as Andrew suggests?

Best regards

Gerold