Merge pull request #731 from spring-iitd/master

Added intelligent AMF selection at gNB
aligungr · Feb 2, 2025 · 5c09fc8 · 5c09fc8
2 parents 7bf0cc9 + 933bca2
commit 5c09fc8
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Showing 5 changed files with 59 additions and 13 deletions.
diff --git a/src/gnb/ngap/management.cpp b/src/gnb/ngap/management.cpp
@@ -33,7 +33,7 @@ void NgapTask::createAmfContext(const GnbAmfConfig &conf)
     m_amfCtx[ctx->ctxId] = ctx;
 }
 
-void NgapTask::createUeContext(int ueId)
+void NgapTask::createUeContext(int ueId, int32_t &requestedSliceType)
 {
     auto *ctx = new NgapUeContext(ueId);
     ctx->amfUeNgapId = -1;
@@ -42,7 +42,7 @@ void NgapTask::createUeContext(int ueId)
     m_ueCtx[ctx->ctxId] = ctx;
 
     // Perform AMF selection
-    auto *amf = selectAmf(ueId);
+    auto *amf = selectAmf(ueId, requestedSliceType);
     if (amf == nullptr)
         m_logger->err("AMF selection for UE[%d] failed. Could not find a suitable AMF.", ueId);
     else

diff --git a/src/gnb/ngap/nas.cpp b/src/gnb/ngap/nas.cpp
@@ -20,13 +20,53 @@
 #include <asn/ngap/ASN_NGAP_ProtocolIE-Field.h>
 #include <asn/ngap/ASN_NGAP_RerouteNASRequest.h>
 #include <asn/ngap/ASN_NGAP_UplinkNASTransport.h>
+#include <ue/nas/enc.hpp>
+#include "encode.hpp"
+#include <stdexcept>
 
 namespace nr::gnb
 {
 
-void NgapTask::handleInitialNasTransport(int ueId, const OctetString &nasPdu, int64_t rrcEstablishmentCause,
-                                         const std::optional<GutiMobileIdentity> &sTmsi)
+int32_t extractSliceInfoAndModifyPdu(OctetString &nasPdu) {
+    nas::RegistrationRequest *regRequest = nullptr;
+    int32_t requestedSliceType = -1;
+    const uint8_t *m_data = nasPdu.data();
+    size_t m_dataLength = nasPdu.length(); 
+    OctetView octetView(m_data, m_dataLength);
+    auto nasMessage = nas::DecodeNasMessage(octetView);  
+    if (nasMessage->epd == nas::EExtendedProtocolDiscriminator::MOBILITY_MANAGEMENT_MESSAGES)
+    {
+        nas::MmMessage *mmMessage = dynamic_cast<nas::MmMessage *>(nasMessage.get());
+        if (mmMessage)
+        {
+            nas::PlainMmMessage *plainMmMessage = dynamic_cast<nas::PlainMmMessage *>(mmMessage);
+            if (plainMmMessage)
+            {
+                regRequest = dynamic_cast<nas::RegistrationRequest *>(plainMmMessage);
+                if (regRequest)
+                {
+                    auto sz = regRequest->requestedNSSAI->sNssais.size();
+                    if (sz > 0) {
+                        requestedSliceType = static_cast<uint8_t>(regRequest->requestedNSSAI->sNssais[0].sst);
+                    }
+                }
+            }
+        }
+    }
+    if (regRequest && regRequest->requestedNSSAI) 
+        regRequest->requestedNSSAI = std::nullopt;  
+
+    OctetString modifiedNasPdu;
+    nas::EncodeNasMessage(*nasMessage, modifiedNasPdu);
+    nasPdu = std::move(modifiedNasPdu);
+    return requestedSliceType;
+}
+
+void NgapTask::handleInitialNasTransport(int ueId, OctetString &nasPdu, int64_t rrcEstablishmentCause,
+                                            const std::optional<GutiMobileIdentity> &sTmsi)
 {
+    int32_t requestedSliceType = extractSliceInfoAndModifyPdu(nasPdu);
+
     m_logger->debug("Initial NAS message received from UE[%d]", ueId);
 
     if (m_ueCtx.count(ueId))
@@ -35,7 +75,7 @@ void NgapTask::handleInitialNasTransport(int ueId, const OctetString &nasPdu, in
         return;
     }
 
-    createUeContext(ueId);
+    createUeContext(ueId, requestedSliceType);
 
     auto *ueCtx = findUeContext(ueId);
     if (ueCtx == nullptr)

diff --git a/src/gnb/ngap/nnsf.cpp b/src/gnb/ngap/nnsf.cpp
@@ -11,11 +11,18 @@
 namespace nr::gnb
 {
 
-NgapAmfContext *NgapTask::selectAmf(int ueId)
+NgapAmfContext *NgapTask::selectAmf(int ueId, int32_t &requestedSliceType)
 {
-    // todo:
-    for (auto &amf : m_amfCtx)
-        return amf.second; // return the first one
+    for (auto &amf : m_amfCtx) {
+        for (const auto &plmnSupport : amf.second->plmnSupportList) {
+            for (const auto &singleSlice : plmnSupport->sliceSupportList.slices) {
+                int32_t supportedSliceType = static_cast<int32_t>(singleSlice.sst);
+                if (supportedSliceType == requestedSliceType) {
+                    return amf.second;
+                }
+            }
+        }
+    }
     return nullptr;
 }
 

diff --git a/src/gnb/ngap/task.hpp b/src/gnb/ngap/task.hpp
@@ -71,7 +71,7 @@ class NgapTask : public NtsTask
     /* Utility functions */
     void createAmfContext(const GnbAmfConfig &config);
     NgapAmfContext *findAmfContext(int ctxId);
-    void createUeContext(int ueId);
+    void createUeContext(int ueId, int32_t &requestedSliceType);
     NgapUeContext *findUeContext(int ctxId);
     NgapUeContext *findUeByRanId(int64_t ranUeNgapId);
     NgapUeContext *findUeByAmfId(int64_t amfUeNgapId);
@@ -98,7 +98,7 @@ class NgapTask : public NtsTask
     bool handleSctpStreamId(int amfId, int stream, const ASN_NGAP_NGAP_PDU &pdu);
 
     /* NAS transport */
-    void handleInitialNasTransport(int ueId, const OctetString &nasPdu, int64_t rrcEstablishmentCause,
+    void handleInitialNasTransport(int ueId, OctetString &nasPdu, int64_t rrcEstablishmentCause,
                                    const std::optional<GutiMobileIdentity> &sTmsi);
     void handleUplinkNasTransport(int ueId, const OctetString &nasPdu);
     void receiveDownlinkNasTransport(int amfId, ASN_NGAP_DownlinkNASTransport *msg);
@@ -118,7 +118,7 @@ class NgapTask : public NtsTask
     void sendContextRelease(int ueId, NgapCause cause);
 
     /* NAS Node Selection */
-    NgapAmfContext *selectAmf(int ueId);
+    NgapAmfContext *selectAmf(int ueId, int32_t &requestedSliceType);
     NgapAmfContext *selectNewAmfForReAllocation(int ueId, int initiatedAmfId, int amfSetId);
 
     /* Radio resource control */

diff --git a/src/ue/nas/mm/messaging.cpp b/src/ue/nas/mm/messaging.cpp
@@ -73,7 +73,6 @@ static void RemoveCleartextIEs(nas::PlainMmMessage &msg, OctetString &&nasMsgCon
         regReq.micoIndication = std::nullopt;
         regReq.networkSlicingIndication = std::nullopt;
         regReq.mmCapability = std::nullopt;
-        regReq.requestedNSSAI = std::nullopt;
         regReq.requestedDrxParameters = std::nullopt;
         regReq.uesUsageSetting = std::nullopt;
         regReq.updateType = std::nullopt;