8----TN_SP008_E1_1 GnGp Interface and GTP Protocol

Gn Interface and GTP overviewV1026

ZTE University

CN Team

TN_SP008_E1_1

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Course Objectives

Gn Interface

GTP protocol

GTP’ protocol




Gn/Gp Interface

n Gn/Gp : Between the GSN nodes

n Gn : Between the GSN nodes within the same PLMN

n Gp : Between the GSN nodes in two different PLMNs.

n The two interfaces adopt GTP for communication

Gn Interface




Gn/Gp Interface

GGSNSGSN

Gn、Gp

GTP-U

L2L1

UDP

IP

GTP-U

L2L1

UDP

IP

GTP-C

L2L1

UDP

IP

GTP-C

L2L1

UDP

IP

User Plane

Control Plane

Gn/Gp

Gn Interface




Course Objectives

Gn Interface

GTP protocol

GTP’ protocol




GTP protocol

n GTP－GPRS Tunneling Protocol

ÑFunction: Encapsulate the network layer packet( IP

packet) in order to add current user information

(such as IMSI and TEID etc.) add source GSN IP

and destination GSN IP to tunnel the packet to

destination GSN.

GTP protocol




GTP PACKEGE FORMAT

UDPIP GTP Payload (IP or PPP)

Route between the SGSN and GGSNRoute between the SGSN and GGSN

Identify the GTP’s well known portIdentify the GTP’s well known port

Identify the GTP sessionIdentify the GTP session

Data flows from end mobile OS stack to host/serverData flows from end mobile OS stack to host/server

GTP protocol




GTP head format

Extension header

N-PDNSequence number

TEIDLengthMessage type

Label

PNS FlagE FlagreservedPTversion

8 168 32 16

Optional partMust have part

Port 2123 for GTP-CPort 2152 for GTP-U

GTP protocol




GTP protocol

n GTP protocol is made up of：

ÑPath management

ÑTunnel management

ÑLocation management

ÑMobility management

GTP protocol




Path management

ÑEcho Request: find out if the peer GSN or RNC is alive

ÑEcho Response: a response to a received Echo Request

ÑVersion Not Support: indicates the latest GTP version that the GTP entity on the identified UDP/IP address can support

ÑSupported Extension Headers Notification: indicates a list of supported Extension Headers that the GTP entity on the identified IP address can support

GTP protocol




Echo Request

n Echo RequestÑAn Echo Request may be sent on a path to another

GSN or RNC to find out if the peer GSN or RNC is alive (see section Path Failure). Echo Request messages may be sent for each path in use.

ÑA path is considered to be in use if at least one PDP context uses the path to the other GSN. When and how often an Echo Request message may be sent is implementation specific but an Echo Request shall not be sent more often than every 60 seconds on each path.

GTP protocol




Echo Response

n Echo Response

ÑThe message shall be sent as a response to a

received Echo Request.

GTP protocol




Echo Request / Echo Response

GGSN

Echo Response

Echo Request

SGSN

GTP protocol




n Version Not Support

ÑThis message contains only the GTP header

and indicates the latest GTP version that the

GTP entity on the identified UDP/IP address

can support.

Version Not Support

GTP protocol

GSN GSN

Version not support (V0)

GTP message (V1)




n Supported Extension Headers NotificationÑThis message indicates a list of supported

Extension Headers that the GTP entity on the identified IP address can support. This message is sent only in case a GTP entity was required to interpret a mandatory Extension Header but the GSN or RNC was not yet upgraded to support that extension header. The GTP endpoint at the GSN or RNC sending this message is marked as not enabled to support some extension headers (as derived from the supported extension header list).

Supported Extension Headers Notification

GTP protocol




Tunnel management

n Tunnel management

ÑCreate PDP Context Request

ÑCreate PDP Context Response

ÑUpdate PDP Context Request

ÑUpdate PDP Context Response

ÑDelete PDP Context Request

ÑDelete PDP Context Response

GTP protocol




Tunnel management (cont.)

n Tunnel Management

ÑPDU Notification Request

ÑPDU Notification Response

ÑPDU Notification Reject Request

ÑPDU Notification Reject Response

GTP protocol




GGSN

Create PDP Context Response （reason etc.）

Create PDP Context Request （MSISDN, PDP address, APN, QoS, SGSN

address etc.）

SGSN

Create PDP Context Request /response

GTP protocol




SGSN GGSN

Update PDP Context Request （QoS, SGSN-B address etc.）

Update PDP Context Response （reason etc.）

PDP Update

GTP protocol




Delete PDP Context Response （reason etc）

Delete PDP Context Request

GGSN SGSN

PDP Delete

GTP protocol




SGSN GGSN

PDU Notification Request （PDP address）

HLR

Send Routeing Info for GPRS（IMSI etc）

Send Routeing Info for GPRS Ack （reason，IMSI etc）

PDU Notification Response （reason etc）

Create PDP Context Request （QoS，MSISDN,PDP address，APN,SGSN address etc）

Create PDP Context Response （reason etc）

PDU Notification Request /Response

GTP protocol




PDU Notification reject Request /Response －MS Detached

SGSN GGSN

PDU Notification reject Request（PDPaddress）

HLR

Send Routeing Info for GPRS（IMSI etc）

Send Routeing Info for GPRS Ack（reason， IMSIetc）

PDU Notification reject Response（reason）

GTP protocol




Location Management

n Location Management

ÑSend Routing Information for GPRS Request

ÑSend Routing Information for GPRS Response

ÑFailure Report Request

ÑFailure Report Response

ÑNote MS GPRS Present Request

ÑNote MS GPRS Present Response

GTP protocol




GGSN GTP-MAP Convert GSN

Send Routeing Info for GPRS Request（IMSI etc）

Send Routeing Info for GPRS Response（reason，IMSI etc）

HLR

Send Routeing Info for GPRS Request（IMSI etc）

Send Routeing Info for GPRS Response（reason，IMSI etc）

Send Routing Information for GPRS Request/Response

GTP protocol




GGSN GTP-MAP Convert GSN

Failure Report Request （IMSI etc）

Failure Report Response （reason etc）

HLR

Failure Report Request（IMSI etc）

Failure Report Response （reason etc）

Failure Report Request /Response

GTP protocol




Note MS GPRS Present Request /Response—MS send attach request

GTP protocol

HLRGTP-MAP

Convert GSN

Note MS GPRS Present Request（IMSI，SGSN address etc）

Note MS GPRS Present Response（ reason etc）

GGSN

Note MS GPRS Present Request（IMSI，SGSN address etc）

Note MS GPRS Present Response（ reason etc）




Mobility Management

n Mobility ManagementÑIdentification Request

ÑIdentification Response

ÑSGSN Context Request

ÑSGSN Context Response

ÑSGSN Context Acknowledge

ÑForward Relocation Request

ÑForward Relocation Response

ÑForward Relocation Complete

GTP protocol




Identification Response（reason etc）

Identification Request（RAI，P-TMSI etc）

SGSN-B SGSN-A

Identification Request /Response

GTP protocol




SGSN-B SGSN-A

SGSN Context Response（reason etc）

SGSN Context Request（RAI,TLLI etc）

SGSN Context Acknowledge（reason etc）

SGSN Context Request /Response/Acknowledge

GTP protocol




Course Objectives

Gn Interface

GTP protocol

GTP’ protocol




GTP’ protocol

n GTP’ protocol－used between GSN and CG to transfer

billing data

Ñ Path management: Provide two signals to detect if the path

between GSN and CG is available or not; provide a pair of

redirection signal to establish redundant billing channel

Ñ CDR transfer: provide a pair of signal for normal CDR

transfer (request and response).

GTP’ protocol




n When CG notifies GSN to send CDR

to another CG (within the same

PLMN), when CG needs to conduct

software or hardware maintenance or

when CG discovers system error,

Redirection Command is needed.

n Redirection Request message carries

IE cause code and suggested CG

address

GSN CG

Redirection Request

Redirection Response

Redirection Req/Resp

GTP’ protocol




GSN CG

Data Record Transfer Request

Data Record Transfer Response

Data Record Transfer Req/Resp

n When GSN sends CDRs to

CG or supporting repeated

CDR prevention mechanism,

Data Record Transfer

command will be activated.

GTP’ protocol







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8----TN_SP008_E1_1 GnGp Interface and GTP Protocol