GTP tunnel seems to exist, but No encapsulation when using libgtpnl

This is merely a historical archive of years 2008-2021, before the migration to mailman3.

A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/osmocom-net-gprs@lists.osmocom.org/.

Papa Tana papa.tana101 at gmail.com
Thu Aug 20 16:05:58 UTC 2020


Well, After debugging, it is more likely to have some bug in my code
because finally, it works after several scenario, but for some reason I
don't understand so far, after a moment, the SGSN requests to delete the
pdp context.

So, I was connected with a real sim card for around 1 minute, great!

But I still need a clarification about what to do about echo-response at
GTP-U because I can only handle echo-response at GTP-C because my ggsn
listen in 2123, but I cannot add any message at all like echo-response in
2152 because libgtpnl manage it.

Best Regards,

Le jeu. 20 août 2020 à 12:49, Papa Tana <papa.tana101 at gmail.com> a écrit :

> Hi,
>
> After successfully making libgtpnl works between 02 Linux Host, now I am
> in the step of connecting one Linux Host to a real live SGSN this morning.
>
> I don't have any particular issue at GTP-C side:
>
>  - the Mobile Station registered on 3G network, requests one activate PDP
> context to the SGSN
>  - the SGSN sends to my ggsn a create PDP context
>  - my ggsn accepts it, and answers with all the needed information, such
> as MS_Address, DNS Address 1, DNS address 2, IP of GGSN-C, IP of GGSN-U,
> TEID Control Plane, TEID user plane, .... everything should be OK.
>  - upon receipt of my creade_pdp_context_response accepted, the SGSN now
> try to establish a Tunnel with the given TEID towards my GGSN
>  - but I cannot see anything on my GTPU-side in ggsn, apart of several
> echo-request message from SGSN
>  - Sure, SGSN try to test connectivity to my ggsn GTPU by using
> echo-request, but no response
>  - I don't know maybe because of no response, or because of SGSN alert me
> with an error gtpu-sm-cause-update-ggsn-path-failure, the SGSN decide to
> send a delete request
>
> So I have 02 questions please:
>
>  - 1) At GTP-C, I can implement all messages(echo-response,
> create-response, delete-response) but at GTPU-side, as the port is used by
> libgtpnl, I cannot implement an echo-response at all ==> So, do libgtpnl is
> supposed to answer or not to an echo-response received from a SGSN at
> GTPU-level?
>
>  - 2) When I tried a Linux-to-Linux setup, it worked because I specified
> the ms_addr and sgsn_addr in the 02 Linux Host.
>  But as I cannot configure anything about the tunnel at SGSN-side(done
> automatically by SGSN), I can only create the tunnel at ggsn-side thanks to
> my user space program, by passing the TEID and ms_addr input to libgtpnl.
> Does it mean that libgtpnl only complies with OpenGGSN, ergw, and
> OpenAirInterface but not intended to ber used with a real SGSN?
>
> Thanks for clarifying me,
> Best Regards,
>
>
> Le lun. 10 août 2020 à 23:00, Harald Welte <laforge at osmocom.org> a écrit :
>
>> Hi Papa,
>>
>> On Sat, Aug 08, 2020 at 10:59:24AM +0300, Papa Tana wrote:
>> > It is working now.
>> > Very simple and stupid mistake from my side at network namespace
>> configuration.
>>
>> I'm very happy to hear it's working successfully.  Sometimes I start to
>> doubt
>> if there are problems in the codebase, but the fact that you report you
>> got it
>> to work is a relief in that regard :)
>> --
>> - Harald Welte <laforge at osmocom.org>
>> http://laforge.gnumonks.org/
>>
>> ============================================================================
>> "Privacy in residential applications is a desirable marketing option."
>>                                                   (ETSI EN 300 175-7 Ch.
>> A6)
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/osmocom-net-gprs/attachments/20200820/27f6ad0b/attachment.htm>


More information about the osmocom-net-gprs mailing list