GTP connection

[lakehalwalid]

hello ,
while configuring my EPC , i had a good response from the Gx interface ( PGW and PCRF are connected , and communicating ) .
But i have some issues with the other nodes , for example the S5 interface , i followed the documentation , but when i try to see in my wireshark , there no GTP messages , here are my configuration files :

[acetcom]

Hi @lakehalwalid

PGW is selected based on MME configuration or HSS db info.

The easiest way to choose a PGW is to set it up in MME configuration file(mme.yaml). However, if the PGW IP is set in the HSS subscriber information, the MME selects the PGW using the subscriber information instead of the configuration file.

Now I have only the sgw/pgw configuration file so I can't figure out why the S5 GTP is not working properly. If you can share wireshark pcap, it may help to solve the problem.

Thanks!
Sukchan

[lakehalwalid]

thank you a lot for your answer ,
I am not using a subscriber yet , i am just testing the EPC , so i guess the MME has to select the PGW in the conf file
this is the mme.yaml file:

and this is the .pcac :

s5-v3.pcap.zip

[acetcom]

There seems to be no problem in the configuration file regarding PGW access.

By the way, there is no signal message in the shared pcap. Can you capture and send the packet for s1ap, diameter, gtpv2 again?

Thanks!

[lakehalwalid]

yes that's the problem , there is no signal message , i was wondering if the s1ap interface is the problem , because i didn't configure it yet ,
her is the capture :
all.pcap.zip
NB: the first pcap , all nodes were stoped only the pgw and sgw were running , in this one all nodes are up

thank you !

[acetcom]

MME-HSS and PGW-PCRF send/receive a diameter message when starting for the first time. This processes are independent of eNB/UE

First, it is recommended to check whether the MME and the eNB are properly connected. You don't have to specify s1ap or you can choose a specific address. If nothing is specified in s1ap, Open5GS is designed to listen to all external IP addresses.

You can check which address is listening through the MME log file as show below.

$ ./install/bin/open5gs-mmed 
Open5GS daemon v1.3.0-8-gfae425b+

07/20 10:02:06.564: [app] INFO: Configuration: '/home/acetcom/Documents/git/open5gs/install/etc/open5gs/mme.yaml' (../src/main.c:54)
07/20 10:02:06.564: [app] INFO: File Logging: '/home/acetcom/Documents/git/open5gs/install/var/log/open5gs/mme.log' (../src/main.c:57)
07/20 10:02:06.609: [app] INFO: MME initialize...done (../src/mme/app-init.c:33)
07/20 10:02:06.609: [gtp] INFO: gtp_server() [192.168.0.11]:2123 (../lib/gtp/path.c:32)
07/20 10:02:06.609: [gtp] INFO: gtp_server() [172.19.0.1]:2123 (../lib/gtp/path.c:32)
07/20 10:02:06.609: [gtp] INFO: gtp_server() [172.17.0.1]:2123 (../lib/gtp/path.c:32)
07/20 10:02:06.609: [gtp] INFO: gtp_server() [2601:144:4100:a220:ad89:fcf1:f7e5:f680]:2123 (../lib/gtp/path.c:32)
07/20 10:02:06.609: [gtp] INFO: gtp_server() [2601:144:4100:a220:c643:4b3a:b0ee:c446]:2123 (../lib/gtp/path.c:32)
07/20 10:02:06.609: [gtp] INFO: gtp_connect() [127.0.0.2]:2123 (../lib/gtp/path.c:59)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [192.168.0.11]:36412 (../src/mme/s1ap-sctp.c:57)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [172.19.0.1]:36412 (../src/mme/s1ap-sctp.c:57)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [172.17.0.1]:36412 (../src/mme/s1ap-sctp.c:57)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [2601:144:4100:a220:ad89:fcf1:f7e5:f680]:36412 (../src/mme/s1ap-sctp.c:57)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [2601:144:4100:a220:c643:4b3a:b0ee:c446]:36412 (../src/mme/s1ap-sctp.c:57)
tp.c:57)
07/20 10:02:06.609: [mme] INFO: s1ap_server() [2601:144:4100:a220:c643:4b3a:b0ee:c446]:36412 (../src/mme/s1ap-sctp.c:57)

Good luck with you!

[lakehalwalid]

okay i'll do it thank you ,
and do you know why i don't have gtp messages , in the pcap , knowing that the configuration is correct ?

[acetcom]

GTP-C messages that can be used without UE/eNB connectivity may be ECHO-REQ/RSP. If another SGW/PGW products initiates ECHO-REQ requests, Open5GS will respond to ECHO-RSP. However, Open5GS is not designed to initiate ECHO-REQ first. Therefore you cannot see any GTP-C messages.

Please let me know if my standard understanding is wrong.

P.S.
If the UE/eNB try to connect normally, the GTP-C message can be captured on wireshark as below.
gtp.pcapng.tar.gz

Thanks!
Sukchan

[lakehalwalid]

so if i understood , i can't see gtp messages unless i configure/use an eNB ?

[acetcom]

Yes!

[lakehalwalid]

thanks a lot for your help !

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