Wireshark don't see traffic on UE's control plane in LTE (using srsLTE-emane)

asked 2019-05-10 20:06:55 +0000

andre88
3 ●1 ●1 ●2

Hi! I'm using srsLTE-emane (https://github.com/adjacentlink/srsLT...), an open source software to emulate LTE network, and running Demonstration 1 that you can find here: https://github.com/adjacentlink/emane...

The software creates some LXC containers: one for UE, one for eNB and one for EPC. I have a network 10.88.1.0/24 used for control plane. Each container is linked to this network through a bridge: 10.88.1.100 is the bridge (letce0), 10.88.1.1 is the EPC (backchan0), 10.88.1.21 is the eNB (backchan0), 10.88.1.2 is the UE (backchan0).

With Wireshark I see traffic of control plane on backchan0 of eNB (10.88.1.21), arriving from backchan0 of UE, but I don't see traffic of control plane on backchan0 of UE (10.88.1.2). I'm not able to understand why. Here are the captured files: https://1drv.ms/f/s!AoGMfEcbAULFlKdwl....

Anyone could help me?

Thank you!!

Andrea

answered 2019-05-11 11:35:19 +0000

Pascal Quantin
5846 ●63 ●65

Hi Andrea,

the communication between the eNB and the Core Network (MME for the control pane, SGW for the data plane) is IP based. That's why you can see respectively the SCTP/S1AP and the IP/UDP/GTP-U packets.

But the communication between the UE and the eNB is not IP based over the air. The NAS/RRC control messages are encapsulated in PDCP/RLC/MAC PDUs that are then modulated / demodulated when transmitted over the air. Presumably the protocol used to simulate the air interface is transmitting IQ samples (or something similar) between the UE and eNB, so you cannot see the RRC messages directly. As far as I know srsUE and srsENB have an option to export the MAC PDUs in a pcap file for offline analysis (you can check their documentation for more details). I do not know how / if this can be easily done with those containers.

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Hi Pascal, sorry for the long delay! Your answer was great! This has solved my problem! Thank you very very much! :)

andre88 ( 2019-07-26 14:11:37 +0000 )edit

Glad to know that it helped. Then please consider accepting my answer.

Best regards, Pascal.

Pascal Quantin ( 2019-07-26 15:45:16 +0000 )edit

I think to have already done it... or not?

andre88 ( 2019-07-26 15:58:05 +0000 )edit

Sorry I missed it ;)

Pascal Quantin ( 2019-07-26 16:02:10 +0000 )edit

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Wireshark don't see traffic on UE's control plane in LTE (using srsLTE-emane)

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