20 Aug
2012
20 Aug
'12
9:35 a.m.
That's a very useful feature for updating presence information on behalf
of some clients that do not support presence, or simply crashed.
I will be watching this space for TCP/TLS support :)
Is there any other existing way to achieve this for clients over TCP/TLS?
Cheers,
Yufei
On 20/08/12 09:13, sr-users-request(a)lists.sip-router.org wrote:
------------------------------ Message: 5 Date: Mon,
20 Aug 2012
10:13:12 +0200 From: "Olle E. Johansson" <oej(a)edvina.net> Subject: Re:
[SR-Users] [sr-dev] new feature: option to remove contacts based on
sip nat keepalives To: miconda(a)gmail.com, Development mailing list of
the sip-router project <sr-dev(a)lists.sip-router.org> Cc: "SIP Router -
Kamailio \(OpenSER\) and SIP Express Router \(SER\) - Users Mailing
List" <sr-users(a)lists.sip-router.org> Message-ID:
<1CD23BC5-1002-4A6E-B42B-09C73530DB11(a)edvina.net> Content-Type:
text/plain; charset="us-ascii" 20 aug 2012 kl. 10:06 skrev
Daniel-Constantin Mierla:
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Yufei Tao
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> Hello,
>
> over the weekend I committed the code that allows to remove contacts from location
table if the device does not respond to several attempts of SIP nat keepalives (usually
OPTIONS requests).
>
> The feature works only for SIP over UDP, being the only transport for which
nathelper module sends keepalives (or sip ping requests as written in some docs).
>
> Also, the lack of keepalive reply is tracked only for location records stored in
memory (so it does not work with db only mode for usrloc). This is because the keepalives
are sent stateless, not using tm module, to avoid overloading of timers and shared memory
when dealing with large subscriber base -- therefore the implementation is very
lightweight in using resources, targeting of course scalability. Detection of replies for
keepalives is done based on from tag which carries the internal unique id of the location
contact (which is available from v3.3).
>
> In order to enable this feature you have to set the keepalive_timeout parameter of
nathelper module -- that's the only addition you have to add to a config that sends
SIP nat keepalives. Internally, the modules store the timestamp of the last SIP keepalive
reply (nathelper detects the right reply and calls usrloc API for storing the timestamp in
contact structure in memory).
>
> http://kamailio.org/docs/modules/devel/modules_k/nathelper.html#id2535244
>
> Before sending a new keepalive to a contact, it is checking if the last keepalive
reply is older than keepalive_timeout value and if yes, will lower the expires to 10
seconds (if the expires is higher). There is no special handling of keepalive reply codes,
all of them will update the last keepalive timestamp.
>
> This feature should be useful in mobile networks, to avoid stacking lot of invalid
contacts which could result in lot of branches causing many retransmissions.
>
> There is plant to go for tcp/tls as well and detect when the connection is down, but
looks like no spare time in the near future. However, right now using
set_forward_no_connect() will avoid trying to create new connections for natted uses whose
registration connection is down.
>
On my personal wish list is to have an event route when a registered device
becomes unreachable - like a closed TCP connection for a device behind NAT or failure to
response to NAT pings.
/O