GTP Interoperability for 2G and 3G Networks

Learn how to control GTP information elements by selectively removing R6, R7, R8, and R9 IEs to optimize roaming interoperability and minimize unnecessary overhead.

The GTP is defined by the third-generation partnership project (3GPP) standards to carry GPRS within third generation (3G) or fourth generation (4G) networks. The information elements (IEs) provide information about GTP tunnels, such as creation, modification, deletion, and status. The IEs are included in all GTP control message packets.

GTP Information Elements

Information elements (IEs) are included in all GTP control message packets. These IEs carry information related to GTP tunnels, such as tunnel creation, modification, deletion, and status. Junos OS supports information elements consistent with Third-Generation Partnership Project (3GPP) Releases 6, 7, 8, and 9. If operators in your network use earlier 3GPP releases, you can reduce network overhead by restricting control messages that contain unsupported IEs. If a new information element is introduced, GTP messages are not dropped. GTP forwards the messages even if it encounters unknown or unsupported IEs.

R6, R7, R8, and R9 Information Elements Removal

The 3GPP R6, R7, R8, and R9 information elements removal feature helps maintain interoperability during roaming between Second-Generation Partnership Project (2GPP) and 3GPP networks.

You can configure a GTP-aware Juniper Networks device that resides at the border between a Public Land Mobile Network (PLMN) and a GPRS Roaming Exchange (GRX) and acts as a Gp firewall to remove 3GPP-specific attributes from the GTP packet header when packets enter a 2GPP network.

The device can be configured to remove the following information elements from GTP messages before forwarding them to the Gateway GPRS Support Node (GGSN):

RAT
RAI
Common Flags
ULI
MS Time Zone
IMEI-SV
Access Point Name (APN) Restriction

Supported R6, R7, R8, and R9 Information Elements

Junos OS supports all 3GPP R6 IEs for GTP), as listed in Table 1.

Table 1: Supported Information Elements
IE Type Value	Information Element
1	Cause
2	International Mobile Subscriber Identity (IMSI)
3	Routing Area Identity (RAI)
4	Temporary Logical Link Identity (TLLI)
5	Packet TMSI (P-TMSI)
8	Reordering Required
9	Authentication Triplet
11	MAP Cause
12	P-TMSI Signature
13	MS Validated
14	Recovery
15	Selection Mode
16	Tunnel Endpoint Identifier Data I
17	Tunnel Endpoint Identifier Control Plane
18	Tunnel Endpoint Identifier Data II
19	Teardown ID
20	NSAPI
21	RANAP Cause
22	RAB Context
23	Radio Priority SMS
24	Radio Priority
25	Packet Flow ID
26	Charging Characteristics
27	Trace Reference
28	Trace Type
29	MS Not Reachable Reason
127	Charging ID
128	End User Address
129	MM Context
130	PDP Context
131	Access Point Name
132	Protocol Configuration Options
133	GSN Address
134	MS International PSTN/ISDN Number (MSISDN)
135	Quality of Service Profile
136	Authentication Quintuplet
137	Traffic Flow Template
138	Target Identification
139	UTRAN Transparent Container
140	RAB Setup Information
141	Extension Header Type List
142	Trigger Id
143	OMC Identity
144	RAN Transparent Container
145	PDP Context Prioritization
146	Additional RAB Setup Information
147	SGSN Number
148	Common Flags
149	APN Restriction
150	Radio Priority LCS
151	RAT Type
152	User Location Information
153	MS Time Zone
154	IMEI-SV
155	CAMEL Charging Information Container
156	MBMS UE Context
157	Temporary Mobile Group Identity (TMGI)
158	RIM Routing Address
159	MBMS Protocol Configuration Options
160	MBMS Service Area
161	Source TNC PDCP context Information
162	Additional Trace Information
163	Hop Counter
164	Selected PLMN ID
165	MBMS Session Identifier
166	MBMS2G/3G Indicator
167	Enhanced NSAPI
168	MBMS Session Duration
169	Additional MBMS Trace Information
173	BSS Container
174	Cell Identification
175	PDU Numbers
176	BSSGP Cause
178	RIM Routing Address Discriminator
179	List of setup PFCS
180	PS Hand-over XID Parameters
188	Reliable INTER RAT HANDOVER INFO
251	Charging Gateway Address
255	Private Extension

Junos OS supports all 3GPP R7 IEs for GTP, as listed in Table 2.

Table 2: Supported Information Elements
IE Type Value	Information Element
172	PS Handover Request Context
181	MS Info Change Reporting Action
182	Direct Tunnel Flags
183	Correlation-ID
184	Bearer Control Mode

Junos OS supports all 3GPP R8 IEs for GTP, as listed in Table 3.

Table 3: Supported Information Elements
IE Type Value	Information Element
189	RFSP Index

Junos OS supports all 3GPP R9 IEs for GTP, as listed in Table 4.

Table 4: Supported Information Elements
IE Type Value	Information Element
190	Fully Qualified Domain Name (FQDN)
191	Evolved Allocation/Retention Priority 1
192	Evolved Allocation/Retention Priority 2
193	Extended Common Flags
194	User CSG Information (UCI)
195	CSG Information Reporting Action
196	CSG ID
197	CSG Membership Indication (CMI)
198	Aggregate Maximum Bit Rate (AMBR)

Example: Remove R6, R7, R8, and R9 Information Elements from GTP Messages

This example shows how to remove R6 information elements from GTP messages.

Requirements
Overview
Configuration

Requirements

No special configuration beyond device initialization is required before configuring this feature.

Overview

In this example, you configure the Gp interface of the security device to remove newly added R6 IEs (RAT, Common Flags, ULI, IMEI-SV, MS Time Zone, and APN restrictions) from the GTP message.

Configuration

Step-by-Step Procedure

To remove R6 information elements from GTP messages:

Specify the GTP profile.

Specify the information element.

If you are done configuring the device, commit the configuration.

ON THIS PAGE