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Interface in which Diameter Protocol is used?

+4 votes

Can some one provide the list of interfaces of LTE or UMTS in which diameter protocol is used?

posted Nov 29, 2013 by anonymous

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3 Answers

+3 votes

It is a big list, it will be easier to look out for something more specific. Control plane in the packet core uses Diameter almost exclusively. You have Gx, Gxx, Rx, S9 for policy control, Rf and Ro (Gx/Gy) for billing, Cx/Dx etc in IMS and many more..... Between any two functional units (PGW-PCRF, P-CSCF-PCRF, OCS-PGW), you will find Diameter interfaces.

answer Nov 29, 2013 by Rathnakumar Kayyar
+2 votes

It is a very long list about 50+ interfaces used diameter Protocol. LTE has one basic rule, any Query and Response protocol of earlier specifications i.e. SS7/GSM/GPRS/UMTS/CDMA is replaced with diameter with a interface pack. Please find the list of interfaces using diameter which I know -

  1. S6a interface MME - HSS.
  2. Gx between PCEF - PCRF
  3. Rx between PCRF- AF(application function).
  4. Sp between PCRF and SPR(subscriber profile repository).
  5. Gy between PCEF and OCS(online charging system).
  6. Gz between PCEF and OFCS(offline charging system).
  7. S6b - PDG and AAA
  8. S6c - PDG and HPLMN
  9. S6d - HSS and SGSN
  10. s9 - HPCRF and VPCRF
  11. S13 - MME and EIR
answer Nov 29, 2013 by Salil Agrawal
+1 vote

Some of them for AAA (Authentication, Authorization and Accounting in the IMS). First, for Authentication and Authorization:

Cx interface: specified between either an I-CSCF or an S-CSCF and an HSS.
Dx interface: specified between either an I-CSCF or an S-CSCF and an SLF.
Sh interface: specified between either an SIP-AS or an OSA-SCS and an HSS.
Zh interface: specified between an HSS and a BSF.
Zn interface: specified between a BSF and a NAF.

Now, for Accounting, Policy and Charging Control in the IMS:

Rx interface: specified between an AF and a PCRF.
Gx interface: specified between a PCRF and a PCEF.
Gz interface: specified between the PCEF and the OFCS
Ro interface: specified between the OCF and any of the following: IMS-GWF, SIP-AS, MRFC or GGSN.
Rf interface: specified between the CDF and any of the following: MRFC, MGCF, BGCF, SIP-AS, P-CSCF, I-CSCF or S-CSCF.

Between LTE’s EPC and IMS:

S6a interface: specified between an MME and the HSS.
SLs interface: specified between an MME and the E-SMLC
SLg interface: specified between an MME and a GMLC.
SLh interface: specified between an HSS and a GMLC.
S13 interface: specified between an MME and an EIR.

Acronyms used for entities involved in Diameter based interfaces described upwards (in order of appearance):

I-CSCF and S-CSCF: Interrogating and Serving Call Session Control Function.
HSS: Home Subscriber Server.
SLF: Subscriber Location Function
SIP-AS: Session Initiation Protocol - Application Server.
OSA-SCS: Open Service Access – Service Capability Server.
BSF: Bootstrapping Server Functionality.
NAF: Network Application Function (operator-controlled functionality)
AF: Application Function (e.g.: SIP-AS, P-CSCF, etc.).
PCRF: Policy and Charging Rules Function.
P-CSCF: Proxy Call Session Control Function.
PCEF: Policy and Charging Enforcement Function
OCF: Online Charging Function.
IMS-GWF: IMS Gateway Function.
MRFC: Media Resource Function Controller.
GGSN: GPRS Gateway Support Node.
OFCS: Offline Charging System.
MGCF: Media Gateway Control Function.
BGCF: Breakout Gateway Control Functions.
EPC: Evolved Packet Core.
MME: Mobility Management Entity.
E-SMLC: Evolved Serving Mobile Location Center.
GMLC: Gateway Mobile Location Center.
EIR: Equipment Identity Register.

For more, better look at 3GPP TS 23.002 and its internal references regarding Diameter interfaces, i.e.:

3GPP TS 29.272: "Evolved Packet System (EPS); Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) related interfaces based on Diameter protocol".
3GPP TS 29.173: "Location Services (LCS); Diameter-based SLh interface for Control Plane LCS".
3GPP TS 29.336: "Home Subscriber Server (HSS) diameter interfaces for interworking with packet data networks and applications".
3GPP TS 29.337: "Diameter based T4 Interface for communications with packet data networks and applications".
3GPP TS 29.338: "Diameter based protocols to support of SMS capable MMEs".
IETF RFC 4006: "Diameter Credit-Control Application".

answer Dec 1, 2013 by anonymous
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