5G(NR)无线网络中APN及分配过程

APN是(AccessPointName)的简写，也就是接入点名称。它是终端在无线互联网的网关(或锚定点)，UE(移动终端)通过接入点(APN)后，才可能访问核心网络，进行数据服务连接。1.APN分配

在无线网络中APN是根据UE的请求，由网络为其分配。APN是UE设置(请求)和网络配置的结合，终端和网络都参与了APN的赋值；

如果APN赋值不正确，终端将不能连接上网；商用电话一般都是根据SIM卡、终端和网络匹配在终端中存储APN。

*现网中个别用户投诉不能上网大多是由于私自更改APN，而网络不支持所致；2.APN分配过程

APN的分配协议和过程非常简单，只需两步就可完成；其分别如下：

2.1

UE-->Network：PDN

ConnectivityRequest（终端请求一个特定APN）2.2

UE<--Network：ActivateDefaultEPSBearerContextRequest(激活包括上下文的默认承载和网络定义一个APN）3.APN分配示例3.1默认APN分配

默认APN的分配包括在RRC+NAS消息中，其过程如下：i)RRC:RRCConnectionSetupComplete+NAS:AttachRequest+

ESM:PDNConnectivityRequestii)RRC:RRCConnectionReconfiguration+NAS:AttachAccept+

NAS:ActivateDefaultEPSBearerContextReq

APN分配的NAS（请求）消息<PDNConnectivityRequest:DefaultAPN>

NASEPSsessionmanagementmessages:PDNconnectivityrequest(0xd0)0011....=PDNtype:IPv4v6(3)....0001=Requesttype:initialrequest(1)ESMinformationtransferflag

1101....=ElementID:0xd-

....000.=Sparebit(s):0x00

.......1=EIT(ESMinformationtransfer):SecurityprotectedESMinformationtransferrequiredProtocolConfigurationOptions

ElementID:0x27

Length:32

[Linkdirection:MStonetwork(0)]

1.......=Extension:True

ConfigurationProtocol:PPPforusewithIPPDPtypeorIPPDNtype(0)

ProtocolorContainerID:InternetProtocolControlProtocol(0x8021)

Length:0x10(16)

PPPIPControlProtocol

Code:ConfigurationRequest(1)

Identifier:0(0x00)

Length:16

Options:(12bytes),PrimaryDNSServerIPAddress,SecondaryDNSServerIPAddress

PrimaryDNSServerIPAddress:0.0.0.0

Type:PrimaryDNSServerIPAddress(129)

Length:6

PrimaryDNSAddress:0.0.0.0(0.0.0.0)

SecondaryDNSServerIPAddress:0.0.0.0

Type:SecondaryDNSServerIPAddress(131)

Length:6

SecondaryDNSAddress:0.0.0.0(0.0.0.0)

AccessPointName

//UEcanspecifyapredefinednamehere.

//IncaseofdefaultEPSbearer,itiscommonthattheAPNisnotspecified

ProtocolorContainerID:DNSServerIPv4AddressRequest(0x000d)

Length:0x00(0)

ProtocolorContainerID:DNSServerIPv6AddressRequest(0x0003)

Length:0x00(0)

ProtocolorContainerID:IPaddressallocationviaNASsignalling(0x000a)

Length:0x00(0)

ProtocolorContainerID:IPv4LinkMTURequest(0x0010)

Length:0x00(0)默认承载激活请求（默认APN）<ActivateDefaultEPSBearerContextRequest:DefaultAPN>

NASEPSsessionmanagementmessages:ActivatedefaultEPSbearercontextrequest(0xc1)EPSqualityofservice

Length:1

QualityofServiceClassIdentifier(QCI):QCI9(9)AccessPointName

Length:8

APN:

internet

//NetworkAssignsaspecificAPNNamePDNaddress

Length:13

00000...=Sparebit(s):0x00

PDNtype:IPv4v6(3)

PDNIPv6ifid:0000000000000001

PDNIPv4:192.168.137.2(192.168.137.2)ProtocolConfigurationOptions

ElementID:0x27

Length:8

[Linkdirection:NetworktoMS(1)]

1.......=Extension:True

ConfigurationProtocol:PPPforusewithIPPDPtypeorIPPDNtype(0)

ProtocolorContainerID:InternetProtocolControlProtocol(0x8021)

Length:0x04(4)

PPPIPControlProtocol

Code:ConfigurationNak(3)

Identifier:0(0x00)

Length:43.2

（网络侧）APN分配（Assignmentofadditional

APN）----VOLTE终端在默认承载激活和APN分配后IMSAPN分配

（网络侧）的APN分配是UE默认承载（和APN）激活之后，再由网络侧为其分配（如IMSAPN），其主要包括两步：

i)RRC:ulinformationTransfer

+

ESM:PDNConnectivityRequest

ii)RRC:RRCConnectionReconfiguration+

NAS:ActivateDefaultEPSBearerContextReqAPN连接请求<PDNConnectivityRequest:AdditionalAPN>

NASEPSsessionmanagementmessages:PDNconnectivityrequest(0xd0)0011....=PDNtype:IPv4v6(3)....0001=Requesttype:initialrequest(1)AccessPointName

ElementID:0x28

Length:4

APN:

ims

//UsuallyUErequestPDNwithspecificAPNnameProtocolConfigurationOptions

ElementID:0x27

Length:41

[Linkdirection:MStonetwork(0)]

1.......=Extension:True

ConfigurationProtocol:PPPforusewithIPPDPtypeorIPPDNtype(0)

ProtocolorContainerID:InternetProtocolControlProtocol(0x8021)

Length:0x10(16)

PPPIPControlProtocol

Code:ConfigurationRequest(1)

Identifier:0(0x00)

Length:16

Options:(12bytes),PrimaryDNSServerIPAddress,SecondaryDNSServerIPAddress

PrimaryDNSServerIPAddress:0.0.0.0

Type:PrimaryDNSServerIPAddress(129)

Length:6

PrimaryDNSAddress:0.0.0.0(0.0.0.0)

SecondaryDNSServerIPAddress:0.0.0.0

Type:SecondaryDNSServerIPAddress(131)

Length:6

SecondaryDNSAddress:0.0.0.0(0.0.0.0)

ProtocolorContainerID:DNSServerIPv4AddressRequest(0x000d)

Length:0x00(0)

ProtocolorContainerID:DNSServerIPv6AddressRequest(0x0003)

Length:0x00(0)

ProtocolorContainerID:P-CSCFIPv6AddressRequest(0x0001)

Length:0x00(0)

ProtocolorContainerID:P-CSCFIPv4AddressRequest(0x000c)

Length:0x00(0)

ProtocolorContainerID:IPaddressallocationviaNASsignalling(0x000a)

Length:0x00(0)

ProtocolorContainerID:MSSupportofNetworkRequestedBearerControlindicator(0x0005)

Length:0x00(0)

ProtocolorContainerID:IPv4LinkMTURequest(0x0010)

Length:0x00(0)

APN的分配（默认承载激活+APN请求）<ActivateDefaultEPSBearerContextReq:AdditionalAPN>

NASEPSsessionmanagementmessages:ActivatedefaultEPSbearercontextrequest(0xc1)

EPSqualityofservice

Length:1

QualityofServiceClassIdentifier(QCI):QCI9(9)

AccessPointName

Length:4

APN:

ims

//NetworkAllocatethespecificAPNName.ThismayormaynotbethesameasUErequested

PDNaddress

Length:13

00000...=Sparebit(s):0x00

PDNtype:IPv4v6(3)

PDNIPv6ifid:0000000000000011

PDNIPv4:192.168.1.11(192.168.1.11)

LinkedTI-Transactionidentifier

ElementID:0x5d

Length:1

0.......=TIFlag:ThemessageissentfromthesidethatoriginatestheTI

TIvalue:0x02(2)

QualityOfService-NegotiatedQoS

ElementID:0x30

Length:14

00......=Sparebit(s):0

..100...=QualityofServiceDelayclass:Delayclass4(besteffort)(4)

.....011=Reliabilityclass:UnacknowledgedGTP/LLC,AckRLC,Protecteddata(3)

1001....=Peakthroughput:Upto256000octet/s(9)

....0...=Sparebit(s):0

.....010=Precedenceclass:Normalpriority(2)

000.....=Sparebit(s):0

...01010=Meanthroughput:100000octet/h(10)

100.....=Trafficclass:Backgroundclass(4)

...10...=Deliveryorder:Withoutdeliveryorder('no')(2)

.....011=DeliveryoferroneousSDUs:ErroneousSDUsarenotdelivered('No')(3)

MaximumSDUsize:1500octets(150)

Maximumbitrateforuplink:64kbps(64)

Maximumbitratefordownlink:384kbps(104)

0111....=ResidualBitErrorRate(BER):1*10-5(7)

....0100=SDUerrorratio:1*10-4(4)

000000..=Transferdelay:Subscribedtransferdelay/reserved(0)

......00=Traffichandlingpriority:Subscribedtraffichandlingpriority/Reserved(0)

Guaranteedbitrateforuplink:64kbps(64)

Guaranteedbitratefordownlink:568kbps(127)

000.....=Sparebit(s):0

...0....=Signallingindication:Notoptimisedforsignallingtraffic

....0000=Sourcestatisticsdescription:unknown(0)

Maximumbitratefordownlink(extended):UsethevalueindicatedbytheMaximumbitratefordownlink(0)

Guaranteedbitratefordownlink(extended):UsethevalueindicatedbytheGuaranteedbitratefordownlink(0)

LLCServiceAccessPointIdentifier-NegotiatedLLCSAPI

ElementID:0x32

0000....=Sparebit(s):0

....0011=LLCSAPI:SAPI3(3)

RadioPriority

1000....=ElementID:0x8-

RadioPriority(PDPorSMS):prioritylevel1(highest)(1)

ProtocolConfigurationOptions

ElementID:0x27

Length:72

[Linkdirection:NetworktoMS(1)]

1.......=Extension:True

ConfigurationProtocol:PPPforusewithIPPDPtypeorIPPDNtype(0)

ProtocolorContainerID:InternetProtocolControlProtocol(0x8021)

Length:0x10(16)

PPPIPControlProtocol

Code:ConfigurationNak(3)

Identifier:0(0x00)

Length:16

Options:(12bytes),PrimaryDNSServerIPAddress,SecondaryDNSServerIPAddress

PrimaryDNSServerIPAddress:10.211.64.87

Type:PrimaryDNSServerIPAddress(129)

Length:6

PrimaryDNSAddress:10.211.64.87(10.211.64.87)

SecondaryDNSServerIPAddress:10.211.64.87

Type:SecondaryDNSServerIPAddress(131)

Length:6

SecondaryDNSAddress:10.211.64.87(10.211.64.87)

ProtocolorContainerID:DNSServerIPv4Address(0x000d)

Length:0x04(4)

IPv4:10.211.64.87

ProtocolorContainerID:DNSServerIPv6Address(0x0003)

Length:0x10(16)

IPv6:2001:0:0:1::2

ProtocolorContainerID:P-CSCFIPv6Address(0x0001)

Length:0x10(16)

IPv6:2001:0:0:1::2

ProtocolorContainerID:P-CSCFIPv4Address(0x000c)

Length:0x04(4)

IPv4:192.168.1.24.S1接口上APN传输协议

APN是终端(UE)与核心网络协商分配，在5G(NR)NSA网络中相关消息通过S1链路（SA网络是在NG接口中）在基站与核心网之间传递；消息内容如下：

4.1

初始建立NAS消息<UplinkNASTransport>S1ApplicationProtocol

S1AP-PDU:initiatingMessage(0)

initiatingMessage

procedureCode:id-uplinkNASTransport(13)

criticality:ignore(1)

value

UplinkNASTransport

protocolIEs:5items

Item0:id-MME-UE-S1AP-ID

ProtocolIE-Field

id:id-MME-UE-S1AP-ID(0)

criticality:reject(0)

value

MME-UE-S1AP-ID:....

Item1:id-eNB-UE-S1AP-ID

ProtocolIE-Field

id:id-eNB-UE-S1AP-ID(8)

criticality:reject(0)

value

ENB-UE-S1AP-ID:3

Item2:id-NAS-PDU

ProtocolIE-Field

id:id-NAS-PDU(26)

criticality:reject(0)

value

NAS-PDU:27a8ccdcee7e024eda2808016e05697370736e

Non-Access-Stratum(NAS)PDU

0010....=Securityheadertype:Integrityprotectedandciphered(2)

....0111=Protocoldiscriminator:EPSmobilitymanagementmessages(0x07)

Messageauthenticationcode:0xa8ccdcee

Sequencenumber:126

0000....=EPSbeareridentity:NoEPSbeareridentityassigned(0)

....0010=Protocoldiscriminator:EPSsessionmanagementmessages(0x02)

Proceduretransactionidentity:78

NASEPSsessionmanagementmessages:ESMinformationresponse(0xda)

AccessPointName

ElementID:0x28

Length:8

APN:

testapn

Item3:id-EUTRAN-CGI

ProtocolIE-Field

id:id-EUTRAN-CGI(100)

criticality:ignore(1)

value

EUTRAN-CGI

...

Item4:id-TAI

ProtocolIE-Field

id:id-TAI(67)

criticality:ignore(1)

value

TAI

...4.2初始上下文建立请求<

InitialContextSetupRequest>S1ApplicationProtocol

S1AP-PDU:initiatingMessage(0)

initiatingMessage

procedureCode:id-InitialContextSetup(9)

criticality:reject(0)

value

InitialContextSetupRequest

protocolIEs:8items

Item0:id-MME-UE-S1AP-ID

ProtocolIE-Field

id:id-MME-UE-S1AP-ID(0)

criticality:reject(0)

value

MME-UE-S1AP-ID:...

Item1:id-eNB-UE-S1AP-ID

ProtocolIE-Field

id:id-eNB-UE-S1AP-ID(8)

criticality:reject(0)

value

ENB-UE-S1AP-ID:3

Item2:id-uEaggregateMaximumBitrate

ProtocolIE-Field

id:id-uEaggregateMaximumBitrate(66)

criticality:reject(0)

value

UEAggregateMaximumBitrate

uEaggregateMaximumBitRateDL:201943030

uEaggregateMaximumBitRateUL:201943030

Item3:id-E-RABToBeSetupListCtxtSUReq

ProtocolIE-Field

id:id-E-RABToBeSetupListCtxtSUReq(24)

criticality:reject(0)

value

E-RABToBeSetupListCtxtSUReq:1item

Item0:id-E-RABToBeSetupItemCtxtSUReq

ProtocolIE-SingleContainer

id:id-E-RABToBeSetupItemCtxtSUReq(52)

criticality:reject(0)

value

E-RABToBeSetupItemCtxtSUReq

e-RAB-ID:5

e-RABlevelQoSParameters

qCI:9

allocationRetentionPriority

priorityLevel:Unknown(12)

pre-emptionCapability:shall-not-trigger-pre-emption(0)

pre-emptionVulnerability:pre-emptable(1)

0.......ExtensionPresentBit:False

transportLayerAddress:0a9bb99c

transportLayerAddress(IPv4):xxx.xxx.xxx.xxx(xxx.xxx.xxx.xxx)

gTP-TEID:...

nAS-PDU:...

Non-Access-Stratum(NAS)PDU

0010....=Securityheadertype:

Integrityprotectedandciphered(2)

....0111=Protocoldiscriminator:

EPSmobilitymanagementmessages(0x07)

Messageauthenticationcode:0x5e7a308b

Sequencenumber:76

0000....=Securityheadertype:

PlainNASmessage,notsecurityprotected(0)

....0111=Protocoldiscriminator:

EPSmobilitymanagementmessages(0x07)

NASEPSMobilityManagementMessageType:Attachaccept(0x42)

0000....=Sparehalfoctet:0

....0...=Sparebit(s):0x00

.....001=Attachresult:EPSonly(1)

GPRSTimer-T3412value

...

Trackingareaidentitylist-TAIlist

...

ESMmessagecontainer

Length:83

ESMmessagecontainercontents:...

0101....=EPSbeareridentity:

EPSbeareridentityvalue5(5)

....0010=Protocoldiscriminator:

EPSsessionmanagementmessages(0x02)

Proceduretransactionidentity:78

NASEPSsessionmanagementmessages:

ActivatedefaultEPSbearercontextrequest(0xc1)

EPSqualityofservice

Length:1

QualityofServiceClassIdentifier(QCI):QCI9(9)

AccessPointName

Length:8

APN:

testapn

PDNaddress

Length:5

00000...=Sparebit(s):0x00

PDNtype:IPv4(1)

PDNIPv4:xxx.xxx.xxx.xxx(xxx.xxx.xxx.xxx)

APNaggregatemaximumbitrate

ElementID:0x5e

Length:6

APN-AMBRfordownlink:8640kbps

APN-AMBRforuplink:8640kbps

APN-AMBRfordownlink(extended):44Mbps

APN-AMBRforuplink(extended):44Mbps

APN-AMBRfordownlink(extended-2):256Mbps

TotalAPN-AMBRfordownlink:308.640Mbps

APN-AMBRforuplink(extended-2):256Mbps

TotalAPN-AMBRforuplink:308.640Mbps

ProtocolConfigurationOptions

....

EPSmobileidentity-GUTI

ElementID:0x50

Length:11

....0...=odd/evenindic:0

.....110=Typeofidentity:GUTI(6)

MobileCountryCode(MCC):001

MobileNetworkCode(MNC):01

MMEGroupID:32774

MMECode:33

M-TMSI:0xc071bb09

EMMcause

ElementID:0x53

Cause:CSdomainnotavailable(18)

GPRSTimer-T3402value

...

GPRSTimer-T3423value

...

PLMNList-EquivalentPLMNs-2PLMNs

ElementID:0x4a

Length:6

PLMN[1]

MobileCountryCode(MCC):001

PLMN[2]

MobileCountryCode(MCC):01

EPSnetworkfeaturesupport

ElementID:0x64

Length:1

....

Additionalupdateresult