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PFCP Session Modification Response should not have Node ID #597
Description
Describe the bug
PFCP Session Modification Response sent by eUPF contains a Node ID element.
According to TS 129.244 V16.4.0 section 7.5.5.1, Node ID element should not appear in PFCP Session Modification Response.
To Reproduce
Steps to reproduce the behavior:
- Launch eUPF with Open5GS SMF.
- Capture PFCP messages on N4 interface.
- Establish PDU session from UE
- Observe packet traces and SMF logs.
Expected behavior
PFCP Session Modification Response does not contain Node ID element.
Screenshots
Packet trace: 1.pcapng.gz
Offending packet is frame 904:
Packet Forwarding Control Protocol
Flags: 0x21, SEID (S)
Message Type: PFCP Session Establishment Response (51)
Length: 112
SEID: 0x0000000000000434
Sequence Number: 5
Spare: 0
Node ID : IPv4 address: 172.25.194.3
IE Type: Node ID (60)
IE Length: 5
0000 .... = Spare: 0
.... 0000 = Address Type: IPv4 address (0)
IPv4: 172.25.194.3
Cause : Request accepted(success)
F-SEID : SEID: 0x0000000000000002, IPv4 172.25.194.3
Created PDR : [Grouped IE]: PDR ID: 2
Created PDR : [Grouped IE]: PDR ID: 3
Created PDR : [Grouped IE]: PDR ID: 4
[Response To: 903]
[Response Time: 0.001017209 seconds]
Logs
Open5GS SMF logs a warning:
�[32m02/28 18:09:57.808�[0m: [�[33msmf�[0m] �[1;37mDEBUG�[0m: smf_state_operational(): SMF_EVT_N4_MESSAGE (../src/smf/smf-sm.c:87)
�[32m02/28 18:09:57.808�[0m: [�[33mcore�[0m] �[37mTRACE�[0m: PARSE L#0 [Cause] T:19 L:1 I:0 (cls:0 vsz:16) off:0x7fb9200adcd8 (../lib/core/ogs-tlv-msg.c:721)
�[32m02/28 18:09:57.808�[0m: [�[33mcore�[0m] �[1;36mWARNING�[0m: Unknown TLV type [60] (../lib/core/ogs-tlv-msg.c:672)
�[32m02/28 18:09:57.808�[0m: [�[33msmf�[0m] �[1;37mDEBUG�[0m: smf_pfcp_state_associated(): SMF_EVT_N4_MESSAGE (../src/smf/pfcp-sm.c:194)
�[32m02/28 18:09:57.808�[0m: [�[33msmf�[0m] �[1;37mDEBUG�[0m: Session Modification Response [5gc] (../src/smf/n4-handler.c:252)
Environment (please complete the following information):
- OS: Ubuntu 24.04 with Linux kernel 6.8.0-53-lowlatency
- 5GC kind and version: Open5GS based on
gradiant/open5gs:2.7.2Docker image - UPF version: based on
ghcr.io/edgecomllc/eupf:49b160078c5eacbe0b944553b309426fa6910c24Docker image
Additional context
This bug was introduced in #541.
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pirog-spb commentedon Mar 1, 2025
Hi @yoursunny
NodeID in PFCP Session Modification/Deletion Response was added in order to keep interoperability with Nokia CMU(SMF). See #540
-- BR Alex
yoursunny commentedon Mar 3, 2025
According to #540 (comment) , Nokia CMU SMF only reacts on NodeID in PFCP Session Establishment Response.
The spec does not allow NodeID in PFCP Session Modification/Deletion Response, and there's no indication that Nokia CMU SMF requires this field.