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Added intelligent AMF selection at gNB #731

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Added intelligent AMF selection at gNB #731

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2da35a6
added intelligent AMF selection at gNB
prateekbhaisora Sep 23, 2024
90c4026
Merge pull request #1 from prateekbhaisora/feature/intelligent-amf-se…
priyanshs Sep 23, 2024
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4 changes: 2 additions & 2 deletions src/gnb/ngap/management.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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, const int32_t &requestedSliceType)
{
auto *ctx = new NgapUeContext(ueId);
ctx->amfUeNgapId = -1;
Expand All @@ -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
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45 changes: 42 additions & 3 deletions src/gnb/ngap/nas.cpp
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Expand Up @@ -20,13 +20,52 @@
#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) {
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Could you explain why the modification is needed for the original PDU

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@prateekbhaisora prateekbhaisora Oct 30, 2024 •
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Yes sure. In the current implementation, the UE is removing the information elements (including slice information), before sending the NAS PDU to gNB [ RemoveCleartextIEs() ]. gNB then selects one AMF blindly and forwards the request to the selected AMF.

Now, to support intelligent AMF selection based on slice type, I have prevented removal of slice info from the PDU, when the UE sends it. Now, at the gNB end, the gNB uses this slice info., to select an appropriate AMF. Before forwarding the PDU to AMF, I had to remove the slice information from the PDU at gNB, else it leads to a "Unsupported Message Type received" error on AMF end.

nas::RegistrationRequest *regRequest = nullptr;
int32_t requestedSliceType = -1;
auto m_data = nasPdu.getData();
OctetView octetView(m_data.data(), m_data.size());
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<int32_t>(regRequest->requestedNSSAI->sNssais[0].sst.getValue());
}
}
}
}
}
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))
Expand All @@ -35,7 +74,7 @@ void NgapTask::handleInitialNasTransport(int ueId, const OctetString &nasPdu, in
return;
}

createUeContext(ueId);
createUeContext(ueId, requestedSliceType);

auto *ueCtx = findUeContext(ueId);
if (ueCtx == nullptr)
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15 changes: 11 additions & 4 deletions src/gnb/ngap/nnsf.cpp
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Expand Up @@ -11,11 +11,18 @@
namespace nr::gnb
{

NgapAmfContext *NgapTask::selectAmf(int ueId)
NgapAmfContext *NgapTask::selectAmf(int ueId, const 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) {
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Please use lower-case for SingleSlice and SingleSlice. Because they are loop variables.

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I see. Will do that.

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Please rename const auto &PlmnSupport to const auto &plmnSupport

and

const auto &SingleSlice to const auto &singleSlice

And please replace const int32_t &requestedSliceType to just int32_t requestedSliceType

for (const auto &SingleSlice : PlmnSupport->sliceSupportList.slices) {
int32_t supportedSliceType = static_cast<int32_t>(SingleSlice.sst.getValue());
if (supportedSliceType == requestedSliceType) {
return amf.second;
}
}
}
}
return nullptr;
}

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6 changes: 3 additions & 3 deletions src/gnb/ngap/task.hpp
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Expand Up @@ -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, const int32_t &requestedSliceType);
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Also make just int32_t requestedSliceType

NgapUeContext *findUeContext(int ctxId);
NgapUeContext *findUeByRanId(int64_t ranUeNgapId);
NgapUeContext *findUeByAmfId(int64_t amfUeNgapId);
Expand All @@ -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);
Expand All @@ -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, const int32_t &requestedSliceType);
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Same thing please

NgapAmfContext *selectNewAmfForReAllocation(int ueId, int initiatedAmfId, int amfSetId);

/* Radio resource control */
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1 change: 0 additions & 1 deletion src/ue/nas/mm/messaging.cpp
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Expand Up @@ -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;
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Could you explain this remove?

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This is to prevent the UE from removing Slice information, before sending the NAS PDU. It is in reference to the comment here.

regReq.requestedDrxParameters = std::nullopt;
regReq.uesUsageSetting = std::nullopt;
regReq.updateType = std::nullopt;
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5 changes: 5 additions & 0 deletions src/utils/octet.hpp
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Expand Up @@ -25,6 +25,11 @@ struct octet
{
}

inline uint8_t getValue() const
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Please remove this function.

You can directly cast to uint8_t in order to convert octet to uint8_t

uint8_t aaa = (uint8_t)bbb;

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@prateekbhaisora prateekbhaisora Oct 30, 2024 •
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I have used the getValue() getter method here as value is a private variable of struct octet and this appeared to me as the most appropriate way to access the value variable from outside, i.e., in the extractSliceInfoAndModifyPdu method. Please let me know, if there is a more recommended way.

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octet has a special converter for uint8_t. Please directly use this converter, and remove the getValue().

Example:

octet someOctet = ....
uint8_t someUint8 = (uint8_t)someOctet

{
return value;
}

/* no explicit */ octet(int32_t value) noexcept : value(static_cast<uint8_t>(value & 0xFF))
{
}
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5 changes: 5 additions & 0 deletions src/utils/octet_string.hpp
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Expand Up @@ -25,6 +25,11 @@ class OctetString
{
}

const std::vector<uint8_t>& getData() const
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data is already present. Please remove this method.

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@prateekbhaisora prateekbhaisora Oct 30, 2024 •
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I believe I used this getter() as m_data was a private member of the Octetstring class and for extractSliceInfoAndModifyPdu(), I needed the data from NAS PDU. Please let me know, if there is a more suitable alternative.

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Yes m_data is private, however we have public data() function. Please use data() function instead.

{
return m_data;
}

explicit OctetString(std::vector<uint8_t> &&data) : m_data(std::move(data))
{
}
Expand Down