How does DummyPacketInterval work?

[Strakapoud]

What happens on the client side? Is it operating system or fbclient who
sends the response?

[Dimitry Sibiryakov]

Strakapoud wrote 20.07.2026 19:27:
> What happens on the client side? Is it operating system or fbclient who sends
> the response?

Firebird client ignores dummy packets. OS sends ACK as usual.
Firebird server responds on dummy packets by dummy packets.

--
WBR, SD.

[Mark Rotteveel]

On 20-07-2026 19:27, Strakapoud wrote:
> What happens on the client side? Is it operating system or fbclient who
> sends the response?

The client will simply consume the message at some point. It does not
send a response. It's about liveness check of TCP/IP. And it's pretty
much not needed any way, as Firebird also uses SO_KEEPALIVE, which works
similar, but on a lower level.

Mark
--
Mark Rotteveel

[Strakapoud]

When I test KeepAlive used by OS than it works, i.e. when the connection
between fb server and client pc dies it is correctly detected and ended
(it disappears in mon$attachments).
When I test DummyPacketInterval it works correctly too.

Unfortunately, this sometimes doesn't work for our customers.
They have set both DummyPacketInterval to 2 minutes and use defult 2
hour KeepAliveTime,
yet sometimes Firebird does not notice that the client process does not
exist even for several hous.
What can be the reason?
What can I do to enhance dead-client detection?

I.


Dne 20.07.2026 v 22:56 'Mark Rotteveel' via firebird-support napsal(a):