G.4.4 EPC

33.1283GPPProtocol and procedures for Lawful Interception (LI)Release 18SecurityStage 3TS

G.4.4.1 The flow-chart

Fgure G.4-3 shows the LIPF logic in determining the host NFs in EPC that have the LI functions for the service type of Data.

Figure G.4-3: LIPF logic for the service type Data in EPC

For the delivery type of IRI + CC, the IRI-POIs, the CC-TFs and the CC-POIs (when EPC is deployed without CUPS) are provisioned. For the delivery type of IRI, the IRI-POIs and the IRI-TFs (when EPC is deployed with CUPS) are provisioned. For the delivery type of CC, the CC-TFs and the CC-POIs (when EPC is deployed without CUPS) are provisioned.

For the LI within the EPC, the CSP may deploy either an SGW-based interception or a PGW-based interception. The LIPF logic in supporting the two deployment options is illustrated in figure G.4-4.

Figure G.4-4: Two deployment options in EPC

The LIPF includes a parameter while provisioning the SGW/SGW-C and PGW/PGW-C.

To PGW/PGW-C, with the SGW based deployment option:

– Provide LI functions only for the targets that are outbound roaming with HR.

SGW/SGW-C, with the PGW based deployment option:

– Provide LI functions only for the targets that are inbound roaming with HR.

The above parameter is needed to avoid both SGW/SGW-C and PGW/PGW-C end up performing the interceptions for the same packet data session.

G.4.4.2 Interception

G.4.4.2.1 PDHR

There are two deployment options for the packet data header reporting. It is expected that the CSP implements one of the two deployment options.

In PDHR option 1, the IRI-POI present in the SGW-U/PGW-U (based on a trigger from IRI-TF present in the SGW-C/PGW-C) or the IRI-POI present in the SGW/PGW generates the xIRI. Accordingly, the IRI-TFs in SGW-C/PGW-C and IRI-POI in SGW/PGW are provisioned.

In PDHR option-2, the CC-POI present in the SGW-U/PGW-U (based on a trigger from CC-TF present in the SGW-C/PGW-C) or the CC-POI present in the SGW/PGW delivers the UP packets as xCC to the MDF3, which in turn, forward the same to the MDF2, and MDF2 would then would generate the IRI messages from the received xCC. Accordingly, the CC-TF in SGW-C/PGW-C, CC-POI in SGW/PGW and the PDHR handling function in MDF3 are provisioned.

G.4.4.2.2 LALS triggering

There are two deployment options for LALS triggering. It is expected that the CSP implements one of the two deployment options.

In LALS triggering option 1, the LTF present in the host NF that has the associated IRI-POI triggers the LI-LCS client. Accordingly, the LTFs in MME, SGW, PGW, SGW-C and PGW-C (when EPC is deployed with CUPS) are provisioned.

In LALS triggering option 2, the LTF present in the MDF2 triggers the LI-LCS Client. Accordingly, the LTF in MDF2 is provisioned.

G.4.4.2.3 SGW/PGW deployment options

For the IRI/CC generation, two deployment options are considered:

– SGW-based.

– PGW-based.

The CSP expected to implement one of the two options.

When SGW/SGW-C is provisioned, if the deployment option is PGW-based approach, then the SGW/SGW-C does not perform an interception unless the target is inbound roaming with HR. Similarly, when the PGW/PGW-C is provisioned, if the deployment option is SGW-based approach, then the PGW/PGW does not perform the interception unless the target is outbound roaming with HR.

G.4.4.2.4 HSS

The HSS is expected to provide the IRI-POI functions in the HPLMN only.

G.4.4.2.5 Summary

Table G.4-2 provides the scope of NF domain that provides the IRI-POI/CC-TF/CC-POI functions for the service type of Data in the EPC for an SGW-based deployment option.

Table G.4-2: Scope of NF domain in EPC providing the LI functions (SGW-based deployment)NFs with LI function

Non-roaming

Roaming with LBO

Roaming with HR

VPLMN

HPLMN

VPLMN

HPLMN

HSS

IRI-POI

n/a

IRI-POI

n/a

IRI-POI

MME

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

SGW

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

SGW

CC-POI

CC-POI

n/a

CC-POI

n/a

PGW

n/a

n/a

n/a

n/a

IRI-POI

PGW

n/a

n/a

n/a

n/a

CC-POI

SGW-C

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

SGW-C

CC-TF

CC-TF

n/a

CC-TF

n/a

SGW-U

CC-POI

CC-POI

n/a

CC-POI

n/a

PGW-C

n/a

n/a

n/a

n/a

IRI-POI

PGW-C

n/a

n/a

n/a

n/a

CC-TF

PGW-U

n/a

n/a

n/a

n/a

CC-POI

PDHR

Option 1

SGW

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

SGW-C

IRI-TF

IRI-TF

n/a

IRI-TF

n/a

SGW-U

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

PGW

n/a

n/a

n/a

n/a

IRI-POI

PGW-C

n/a

n/a

n/a

n/a

IRI-TF

PGW-U

n/a

n/a

n/a

n/a

IRI-POI

Option 2

SGW

CC-POI

CC-POI

n/a

CC-POI

n/a

SGW-C

CC-TF

CC-TF

n/a

CC-TF

n/a

SGW-U

CC-POI

CC-POI

n/a

CC-POI

n/a

PGW

n/a

n/a

n/a

n/a

CC-POI

PGW-C

n/a

n/a

n/a

n/a

CC-TF

PGW-U

n/a

n/a

n/a

n/a

CC-POI

MDF3

PDHR

PDHR

n/a

PDHR

PDHR

LALS triggering

Option 1

SGW

LTF

LTF

n/a

LTF

n/a

SGW-C

LTF

LTF

n/a

LTF

n/a

PGW

n/a

n/a

n/a

n/a

LTF

PGW-C

n/a

n/a

n/a

n/a

LTF

Option 2

MDF2

LTF

LTF

n/a

LTF

LTF

Table G.4-3 provides the scope of NF domain that provides the IRI-POI/CC-TF/CC-POI functions for the service type of Data in the EPC for a PGW-based deployment option.

Table G.4-3: Scope of NF domain in EPC providing the LI functions (PGW-based deployment)

NFs with LI function

Non-roaming

Roaming with LBO

Roaming with HR

VPLMN

HPLMN

VPLMN

HPLMN

HSS

IRI-POI

n/a

IRI-POI

n/a

IRI-POI

MME

IRI-POI

IRI-POI

n/a

IRI-POI

n/a

SGW

n/a

n/a

n/a

IRI-POI

n/a

SGW

n/a

n/a

n/a

CC-POI

n/a

PGW

IRI-POI

IRI-POI

n/a

n/a

IRI-POI

PGW

CC-POI

CC-POI

n/a

n/a

CC-POI

SGW-C

n/a

n/a

n/a

IRI-POI

n/a

SGW-C

n/a

n/a

n/a

CC-TF

n/a

SGW-U

n/a

n/a

n/a

CC-POI

n/a

PGW-C

IRI-POI

IRI-POI

n/a

n/a

IRI-POI

PGW-C

CC-TF

CC-TF

n/a

n/a

CC-TF

PGW-U

CC-POI

CC-POI

n/a

n/a

CC-POI

PDHR

Option 1

SGW

n/a

n/a

n/a

IRI-POI

n/a

SGW-C

n/a

n/a

n/a

IRI-TF

n/a

SGW-U

n/a

n/a

n/a

IRI-POI

n/a

PGW

IRI-POI

IRI-POI

n/a

n/a

IRI-POI

PGW-C

IRI-TF

IRF-TF

n/a

n/a

IRI-TF

PGW-U

IRI-POI

IRI-POI

n/a

n/a

IRI-POI

Option 2

SGW

n/a

n/a

n/a

CC-POI

n/a

SGW-C

n/a

n/a

n/a

CC-TF

n/a

SGW-U

n/a

n/a

n/a

CC-POI

n/a

PGW

CC-POI

CC-POI

n/a

n/a

CC-POI

PGW-C

CC-TF

CC-TF

n/a

n/a

CC-TF

PGW-U

CC-POI

CC-POI

n/a

n/a

CC-POI

MDF3

PDHR

PDHR

n/a

PDHR

PDHR

LALS triggering

Option 1

SGW

n/a

n/a

n/a

LTF

n/a

SGW-C

n/a

n/a

n/a

LTF

n/a

PGW

LTF

LTF

n/a

n/a

LTF

PGW-C

LTF

LTF

n/a

n/a

LTF

Option 2

MDF2

LTF

LTF

n/a

LTF

LTF

NOTE 1: The use of "n/a" in the above table implies that the LI function is not applicable to the NF for the indicated scenario.

NOTE 2: The LIPF is not aware of the above role played by the host NFs in providing the LI functions.

NOTE 3: MDF2, MDF3 and LI-LCS Client which are also involved in providing the LI functions are not shown in the tables above.