Configuring TCP keep alive and connection lifetime

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Pascal Maugeri

7 May 2010 7 May '10

2:20 p.m.

"kamailio" users@lists.kamailio.org,

I am sorry to ask again about this topic but I don't understand yet how the TCP keep-alive are sent.

With Kamailio 3.0.1 and the following configuration:

tcp_keepalive=yes tcp_keepidle=10 tcp_connection_lifetime=3600

The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle.

But I don't understand why the time between KA is not linear:

first KA is sent 10 seconds after last last TCP message. This is logical and connected with the tcp_keepidle=10 configuration.

then 2nd KA is sent 75 seconds after first KA

Then my client sends some traffic and 23 seconds after last message, a new KA is sent. Another time it was 54 seconds. etc. etc.

Could you explain me where do come from these values of 75 seconds, 23, 54 ?

Everything works well: my client behind NAT is kept connected but I'd like to understand why it does work :-)

Thanks in advance, Pascal

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Henning Westerholt

7 May 7 May

5:28 p.m.

On Friday 07 May 2010, Pascal Maugeri wrote:

...

tcp_keepalive=yes tcp_keepidle=10 tcp_connection_lifetime=3600

The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle.

But I don't understand why the time between KA is not linear: [..] Could you explain me where do come from these values of 75 seconds, 23, 54 ?

Everything works well: my client behind NAT is kept connected but I'd like to understand why it does work :-)

Hi Pascal,

sounds indeed interesting. :-) Perhaps a problem with the internal timers.. Do noticed also other timer related problems, like for internal INVITE 408 replies or similar?

Cheers,

Henning

Pascal Maugeri

9 May 9 May

10:42 a.m.

Thanks for your Henning, at least I will sleep better knowing I am not completly idiot :-))

I haven't noticed related to INVITE timers (such as the 408) because I only make my client behind NAT to register and re-register and verify it is always reachable in time thanks to this TCP keep-alive. Tomorrow I will try to make a couple a calls to see if I get this 408 you mentionned.

Is there a way (either with a parameter or changing source code) a to control the frequency of TCP k.a. ?

Cheers Pascal

2010/5/7 Henning Westerholt henning.westerholt@1und1.de

...

On Friday 07 May 2010, Pascal Maugeri wrote:

...
tcp_keepalive=yes tcp_keepidle=10 tcp_connection_lifetime=3600

The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle.

But I don't understand why the time between KA is not linear: [..] Could you explain me where do come from these values of 75 seconds, 23,

54

...
?

Everything works well: my client behind NAT is kept connected but I'd

like

...
to understand why it does work :-)

Hi Pascal,

sounds indeed interesting. :-) Perhaps a problem with the internal timers.. Do noticed also other timer related problems, like for internal INVITE 408 replies or similar?

Cheers,

Henning

Daniel-Constantin Mierla

10 May 10 May

9:04 a.m.

Hello,

On 5/9/10 12:42 PM, Pascal Maugeri wrote:

...

Thanks for your Henning, at least I will sleep better knowing I am not completly idiot :-))

I haven't noticed related to INVITE timers (such as the 408) because I only make my client behind NAT to register and re-register and verify it is always reachable in time thanks to this TCP keep-alive. Tomorrow I will try to make a couple a calls to see if I get this 408 you mentionned.

Is there a way (either with a parameter or changing source code) a to control the frequency of TCP k.a. ?

Starting with 3.0, most of tcp parameters are changeable at runtime via RPC (you can use sercmd): http://www.kamailio.org/dokuwiki/doku.php/features:new-in-3.0.x#transport_la...

The initial value can be set via global parameters: http://www.kamailio.org/dokuwiki/doku.php/core-cookbook:3.0.x#tcp_parameters

Cheers, Daniel

...

Cheers Pascal

2010/5/7 Henning Westerholt <henning.westerholt@1und1.de mailto:henning.westerholt@1und1.de>

On Friday 07 May 2010, Pascal Maugeri wrote:
> tcp_keepalive=yes
> tcp_keepidle=10
> tcp_connection_lifetime=3600
>
>
> The TCP connection is kept alive and TCP Keep-Alive packets are
sent when
> the TCP connection is idle.
>
> But I don't understand why the time between KA is not linear:
> [..]
> Could you explain me where do come from these values of 75
seconds, 23, 54
>  ?
>
> Everything works well: my client behind NAT is kept connected
but I'd like
> to understand why it does work :-)

Hi Pascal,

sounds indeed interesting. :-) Perhaps a problem with the internal
timers.. Do
noticed also other timer related problems, like for internal
INVITE 408
replies or similar?

Cheers,

Henning

SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

-- Daniel-Constantin Mierla * http://www.asipto.com/ * http://twitter.com/miconda * http://www.linkedin.com/in/danielconstantinmierla

Klaus Darilion

12:33 p.m.

Hi Pascal!

The TCP keepalive is not an application layer keep alive, but Kamailio just sets the SO_KEEPALIVE socket option. The the TCP keep alive is implemented and performed by the operating systems.

Thus, if you want to tweak the TCP keep alive, then you have to tweak the kernel.

regards Klaus

Am 07.05.2010 16:20, schrieb Pascal Maugeri:

...

"kamailio" <users@lists.kamailio.org mailto:users@lists.kamailio.org>,

Hi

I am sorry to ask again about this topic but I don't understand yet how the TCP keep-alive are sent.

With Kamailio 3.0.1 and the following configuration:
tcp_keepalive=yes
tcp_keepidle=10
tcp_connection_lifetime=3600
The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle.

But I don't understand why the time between KA is not linear:

first KA is sent 10 seconds after last last TCP message. This is logical and connected with the tcp_keepidle=10 configuration.

then 2nd KA is sent 75 seconds after first KA

Then my client sends some traffic and 23 seconds after last message, a new KA is sent. Another time it was 54 seconds. etc. etc.

Could you explain me where do come from these values of 75 seconds, 23, 54 ?

Everything works well: my client behind NAT is kept connected but I'd like to understand why it does work :-)

Thanks in advance, Pascal

SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

Pascal Maugeri

11 May 11 May

8:04 a.m.

I just checked these parameters in runtime (using sysctl -a | grep "tcp_keepalive") and I get:

net.ipv4.tcp_keepalive_time = 7200 net.ipv4.tcp_keepalive_probes = 9 net.ipv4.tcp_keepalive_intvl = 75

I recognize the "75" value used in the delay between my k.a. ! It gets clearer :-)

My question is: does kamailio set somewhow (parameter of source code constant definition) this net.ipv4.tcp_keepalive_intvl parameter ? Or should I fine tune myself in the OS kernel configuration ?

Cheers Pascal

On Mon, May 10, 2010 at 2:33 PM, Klaus Darilion < klaus.mailinglists@pernau.at> wrote:

...

Hi Pascal!

The TCP keepalive is not an application layer keep alive, but Kamailio just sets the SO_KEEPALIVE socket option. The the TCP keep alive is implemented and performed by the operating systems.

Thus, if you want to tweak the TCP keep alive, then you have to tweak the kernel.

regards Klaus

Am 07.05.2010 16:20, schrieb Pascal Maugeri:

...
"kamailio" <users@lists.kamailio.org mailto:users@lists.kamailio.org>,

Hi

I am sorry to ask again about this topic but I don't understand yet how the TCP keep-alive are sent.

With Kamailio 3.0.1 and the following configuration:

tcp_keepalive=yes tcp_keepidle=10 tcp_connection_lifetime=3600

The TCP connection is kept alive and TCP Keep-Alive packets are sent when the TCP connection is idle.

But I don't understand why the time between KA is not linear:

first KA is sent 10 seconds after last last TCP message. This is logical and connected with the tcp_keepidle=10 configuration.

then 2nd KA is sent 75 seconds after first KA

Then my client sends some traffic and 23 seconds after last message, a new KA is sent. Another time it was 54 seconds. etc. etc.

Could you explain me where do come from these values of 75 seconds, 23, 54 ?

Everything works well: my client behind NAT is kept connected but I'd like to understand why it does work :-)

Thanks in advance, Pascal

SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

Klaus Darilion

9:55 a.m.

Am 11.05.2010 10:04, schrieb Pascal Maugeri:

...

Hi

I just checked these parameters in runtime (using sysctl -a | grep "tcp_keepalive") and I get:

net.ipv4.tcp_keepalive_time = 7200 net.ipv4.tcp_keepalive_probes = 9 net.ipv4.tcp_keepalive_intvl = 75

I recognize the "75" value used in the delay between my k.a. ! It gets clearer :-)

My question is: does kamailio set somewhow (parameter of source code constant definition) this net.ipv4.tcp_keepalive_intvl parameter ? Or should I fine tune myself in the OS kernel configuration ?

Probably the fastest way is to grep the source code for tcp_keepalive_intvl and similar (tcp_keepidle ...)

regards klaus

...

Cheers Pascal

On Mon, May 10, 2010 at 2:33 PM, Klaus Darilion <klaus.mailinglists@pernau.at mailto:klaus.mailinglists@pernau.at> wrote:

Hi Pascal!

The TCP keepalive is not an application layer keep alive, but
Kamailio just sets the SO_KEEPALIVE socket option. The the TCP keep
alive is implemented and performed by the operating systems.

Thus, if you want to tweak the TCP keep alive, then you have to
tweak the kernel.

regards
Klaus

Am 07.05.2010 16:20, schrieb Pascal Maugeri:

    "kamailio" <users@lists.kamailio.org
    <mailto:users@lists.kamailio.org>
    <mailto:users@lists.kamailio.org
    <mailto:users@lists.kamailio.org>>>,


    Hi

    I am sorry to ask again about this topic but I don't understand
    yet how
    the TCP keep-alive are sent.

    With Kamailio 3.0.1 and the following configuration:

        tcp_keepalive=yes
        tcp_keepidle=10
        tcp_connection_lifetime=3600


    The TCP connection is kept alive and TCP Keep-Alive packets are sent
    when the TCP connection is idle.

    But I don't understand why the time between KA is not linear:

    first KA is sent 10 seconds after last last TCP message. This is
    logical
    and connected with the tcp_keepidle=10 configuration.

    then 2nd KA is sent 75 seconds after first KA

    Then my client sends some traffic and 23 seconds after last
    message, a
    new KA is sent. Another time it was 54 seconds. etc. etc.

    Could you explain me where do come from these values of 75
    seconds, 23, 54 ?

    Everything works well: my client behind NAT is kept connected
    but I'd
    like to understand why it does work :-)

    Thanks in advance,
    Pascal



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participants (4)

Daniel-Constantin Mierla
Henning Westerholt
Klaus Darilion
Pascal Maugeri