TEKELEC - DRA_Diameter and DSR Overview.pdf

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Overview

EAGLE XG

Diameter and Diameter Signaling Router

Carlos Arias Fernandez

Tekelec. For What’s Next.

March 2012



Agenda

› Diameter Overview

› Use of Diameter in LTE/IMS/3G

› DSR Use Cases

Core Relay/Proxy 3G/LTE/IMS

S6/S9 Roaming Proxy (Diameter Edge Agent) LTE/IMS

Policy Proxy 3G/LTE/IMS (Gx/Gxx/Rx/S9)

HSS Proxy LTE/IMS (S6/Cx/Dx/Sh/Dh)

Charging Proxy 3G/LTE/IMS (Rf/Gy/Ro)

Tekelec Confidential2 I Tekelec. For What’s Next.



Diameter



Session Management

› Diameter and SIP become the dominant signaling protocols

› SCTP “point-to-point” connections remain

Mobility and Subscriber Management

Application and Session Control



Diameter Comparison to SS7


Characteristic SS7 Diameter

Routing › Each message independently routed

› Answer message does not contain

routing info and follows same path

as associated request

Signaling network management

(SNM) and Congestion control

› Network-wide

› Dedicated SNM msgs

› Route around failed paths

› Congestion levels and traffic

priorities defined

› Hop-by-hop

› No dedicated SNM msgs

› Failures „discovered‟ with each new

request

› Relies on reliable transport

› No defined traffic priorities

Subscriber number based routing › GTT can be used by upper layers

› Specialized, app-specific proxies

required

DRA for PCRF

HSS address resolution for EPC and

IMS

Robustness› Wide-scale deployment; years of

experience

› Early days; lots of prove-in still

required



Example Diameter Message – Update Location

6 I Tekelec. For What’s Next.

MME

AAA

HSS

Update LocationS6a





MME

AAAHSS

Update LocationS6a





MME

AAAHSS

Update LocationS6a



Use of Diameter in LTE/IMS/3G



Selected Diameter Interfaces in 3G, LTE and IMS

Interface Endpoints

S6a MME HSS

S6d HSS vSGSN (Rel 8)

S13 MME EIR

S9 hPCRF vPCRF

Rx PCRF AF, P-CSCF

Gx PGW PCRF

Gy PGW OCF

Gz PGW OFCF

Cx I/S-CSCF HSS

Sh AF, IP-SM-GW HSS

Rf P/I/S-CSCF, AF OFCF

Ro S-CSCF, AF OCF

Rc OCF ABMF

Re OCF RF



Selected Diameter Interfaces in LTE (EPC) and IMS

Foreign LTE Domain

Home LTE/IMS Domain

Foreign GPRS Domain

S13

S6a S9S6d

GxGz

Gy

Cx

Sh

Rx

Ro

Rf

Rc Re

EIR

vMME vPCRF

PGW

AF

ABMF RF

OFCF

MAP-Diam

IWF

vSGSN

vS4-SGSN

OCF

EPC Equipment

Check

AS Access

to HSS

IMS PCC

IMS

Charging

EPC

Charging

IMS

Registration

EPC Mobility

Management

MME

I/S-CSCFPCRF

P-CSCF

IP-SM-GWAAAHSS

SLF

Gr

Policy

SPR

Sh

Tekelec Confidential11 | Tekelec. For What's Next.



Diameter Agents in 3GPP and GSMA

› 3GPP TR 29.909 – Diameter-based

protocols usages and recommendations

in 3GPP

Defines need for Diameter infrastructure

to simplify the S6 and S9 network

› 3GPP TS 23.203 – Policy and charging

control architecture

Defines Diameter routing agent to direct

all messages for the same IP-CAN

session to the same PCRF

› GSMA PRD IR.88 – LTE Roaming

Guidelines

Defines need for a Diameter agent at the

point of network demarcation


Border Diameter

Relay Pool

Inter-operator Diameter

Infrastructure

Inner Diameter

Relay Pool

S4

SGSN

vPCRF

VPMN HPMN

Proxy

Agent

hPCRF

Proxy

Agent

S6a

S6d

S9

GRX/IPX

S-GW

P-GW

Non-3GPP

GW

ePDG

AF

Gx, Gxa, Gxb, Gxc, Rx

Diameter (PCRF) realm

DRADRA

Diameter (PCRF) realm

DRADRA

PLMN

MME MME MME

MME

PCRF

PCRF

HSS

HSS



Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network

VisibilityCentralized

Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Network-wide

PCRF Binding

Roaming

Steering

MAP/Diameter

Interworking

HSS/MME/PCRFTopology Hiding

IPsec

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)

Policy Proxy

3G/LTE/IMS

(Gx/Gxx/Rx/S9)

Roaming Proxy

LTE/IMS

(S6/S9)

HSS Proxy

LTE/IMS

(S6/Cx/Dx/Sh/Dh)

14 I Tekelec. For What’s Next. Tekelec Confidential

OCS/OFCS

Session-based

Routing

Charging Proxy

3G/LTE/IMS

(Rf/Gy/Ro)

OCS/OFCS

Topology HidingPCRF

Topology Hiding

Tekelec DSR - A Multi-application Diameter Agent

HSSOCS/OFCS

PCRF

Agent

GGSN

PGWMME CSCF

Other

Networks

IMS HSS

Address

Resolution

LTE HSS

Address

Resolution

HSS

Topology Hiding OCS/OFCS

Address

Resolution



Core Relay/Proxy 3G/LTE/IMS

Use Cases



Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)


Core Relay



Scalability and connection Management



Use Case - 3G Mobile Data Architecture


Gx+ and Gy

DRALB

DRALB

DRALB

DRALB

DRALB

DRALB

SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

10 PCRF‟s/Site

8 SBCF‟s/Site

10 PCRF‟s/Site

8 SBCF‟s/Site

10 PCRF‟s/Site

8 SBCF‟s/Site

Load balancers

can vary from

connection

balancers to

specialized

Diameter proxies

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

PCRF

PCRF

PCRF

PCRF

PCRF

PCRF



Use Case - 3G Mobile Data Net with Diameter Relay


SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

10 PCRF‟s/Site

8 SBCF‟s/Site

10 PCRF‟s/Site

8 SBCF‟s/Site

10 PCRF‟s/Site

8 SBCF‟s/Site

Enables future

separation of SBCF

and ABMF via

Diameter

interconnect

Addresses connection

limitations at GGSN

Eliminates need for

load balancers in front

of PCRFs and SBCFs

SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

PCRF

PCRF

PCRF

PCRF

PCRF

PCRF

DSR

DSR



One Region Initial Configuration

MME

MME

MME

HSS Mated Pair

HSS1-Site A

HSS1-Site B

DSR

DSR

• Assumes 2M capacity of MME

• Assumes 6M capacity of HHS

• 4 MME-DSR connections -

NEVER NEED TO CHANGE

• 4 DSR-HSSFE connections -

ONLY CHANGE W ITH HSS

ARCH/CAPACITY CHANGES,

NOT WITH MME CHANGES

MME

MME

MME

FE

FE

DB

DB

HSS Mated Pair

HSS1-Site A

HSS1-Site B

DB

DB

FE

FE




Expand Region to 2 HSS’s with HSS DRA

MME

MME

MME

HSS Mated Pair

HSS1-Site A

HSS1-Site B

Required new connections

Potential new connections to

reduce HSS FE Relay load

DB

DB

HSS Mated Pair

HSS2-Site A

HSS2-Site B

DB

DB

MME

MME

MME

FE

FE

FE

FE




Expand Region to 2 HSS’s with DSR

MME

MME

MME

HSS Mated Pair

HSS1-Site A

HSS1-Site B


DB

DB

HSS Mated Pair

HSS2-Site A

HSS2-Site B

DB

DB

MME

MME

MME

DSR

DSR

FE

FE

FE

FE




Expand Region to 3 HSS’s with HSS DRA

MME

MME

MME

HSS Mated Pair

HSS1-Site A

HSS1-Site B


Potential new connections to

reduce HSS FE Relay load

DB

DB

HSS Mated Pair

HSS2-Site A

HSS2-Site B

DB

DB

MME

MME

MME

H S S M a t e d P ai r

HSS3-Site A

HSS3-Site B

DB

DB

MME

MME

MME

FE

FE

FE

FE

FE

FE




Expand Region to 3 HSS’s with DSR

MME

MME

MME


MME

MME

MME

DSR

DSR


HSS2-Site A

HSS2-Site B

DB

DB

H S S M a t e

d P ai r

HSS1-Site A

HSS1-Site B

DB

DB


HSS3-Site A

HSS3-Site B

DB

DB

MME

MME

MME

FE

FE

FE

FE

FE

FE




The HSS Mesh - Network View

Site 1-ABC

HSSA HSSB HSSC

Site 2-ABC

HSSA HSSB HSSC

S i t e 1 - M N O

H S S M

H S S N

H S S O

S i t e2 -DE F

H S S D

H S S E

H S S F

Site 1-JKL

HSSJ HSSK HSSL

Site 2-GHI

HSSG HSSH HSSI

This blue lines represent one HSS‟s

connections to all other HSS‟s but its

mate (28 connections assuming only asingle connection between HSS‟s is

sufficient). All HSS‟s will have at least one

connection to all other HSS‟s except it‟s

mate, for a minimum of 840 connections

for 15 mated pairs of HSS‟s.




The DSR Mesh - Network View

Site 1-ABC

HSSA HSSB HSSC

Site 2-ABC

HSSA HSSB HSSC

S i t e 1 - M N O

H S S M

H S S N

H S S O

S i t e2 -DE F

H S S D

H S S E

H S S F

Site 1-JKL

HSSJ HSSK HSSL

Site 2-GHI

HSSG HSSH HSSI

DSR DSR

DSR DSR

D S R D

S R

This blue lines represent one DSR‟s

connections to all other DSR‟s (9

connections assuming only a singleconnection between DSR‟s is

sufficient). All DSR‟s will have at least

one connection to all other DSR‟s, for

a minimum of 90 connections for 5

mated pairs of DSR‟s.




Message Handling

DSR R ti T bl



DSR Routing Tables

› An important feature of DSR is the ability to support local applications such as PolicyDRA and HSS Address Resolution in 3GPP networks.

› Local applications may be invoked when a Request message is first received from a

downstream peer, prior to invoking message routing to an upstream peer. To facilitatethis two step process, two routing table have been defined:

Application Routing Table (ART) - contains a prioritized list of user-configurable routing ruleswhich define which local applications to invoke and in which order based upon messagecontent

Peer Routing Table (PRT) - contains a prioritized list of user-configurable routing rules whichdefine where to route a message to an upstream peer based upon message content

A PRT rule can be associated with a Route List which contains a prioritized list of peers usedto route a Request message.

Peer

N-1

Peer

N+1

Appl-1 Appl-2

ApplicationRouting

Table

Peer Routing

Table

RouteList

Table

(2) (3)

(4) (5) (6)

UpstreamDownstream DSR

(1)

Request

28 I Tekelec. For What’s Next.Tekelec Confidential

DSR R ti R t R ti P t



DSR Routing – Request Routing Parameters

› DSR allows the operator to define routing rules based on combinationsof the following data elements:

Destination-Realm (leading/trailing characters, exact match or wildcard)

Destination-Host (leading/trailing characters, exact match, wildcard orpresence/absence)

Application-ID (exact match or wildcard).

› In addition to the above, the following data elements are supported in

DSR to facilitate screening, application invocation, and enhancedrouting:

Command-Code (exact match or wildcard)

Origin-Realm (leading/trailing characters, exact match or wildcard)

Origin-Host (leading/trailing characters, exact match or wildcard)

› DSR allows the operator to prioritize rules for cases where a DiameterRequest may match multiple user defined rules


E l P R ti i RT d R t Li t



Example – Peer Routing using RT and Route Lists

Routing Table (RT)

Dest-Realm* Orig-Realm* Appl ID* Dest-Host* Orig-Host*Cmd-

Code*Action

Route List

NamePri

opco1.com homeop.com Don‟t care Don‟t care Don‟t care Route toPeer HUB_NW 1

opco2.com homeop.com Don‟t care Don‟t care Don‟t careRoute to

Peer OPCO2_NW 1

homeop.com opco1.com 43 Don‟t care Don‟t careRoute to

Peer HSS1 1

homeop.com opco2.com 65 Don‟t care Don‟t careRoute to

Peer MME2 1

Don‟t care Don‟t care Don‟t care Don‟t care Don‟t care Send Answer“X”

--- 99

Route List Table

Route List Name Route Name Pri Weight

HUB_NW HUB_PEER1 1 60




OPCO2_NW OPCO2_PEER1 1 100

OPCO2_NW OPCO2_PEER2 2 100

HHS1 HSS1_SRV1 1 100

MME1 MME1_SRV1 1 100

MME1 MME1_SRV2 2 100

Active Route Group

Standby Route Group


M lti l R t G i R t Li t C t l Vi



Multiple Route Groups in a Route List – Conceptual View

Peer1

Peer2

Peer3

Peer4

Peer5

Peer6

Peer7

W=40

W=30

W=30

W=60

W=40

W=50

W=50

Route Group-1

(Routes with Pri=1)

Route Group-2(Routes with Pri=2)

Route Group-3(Routes with Pri=3)

DSR

Route List-1

Route Group-1

Route Group-2

Route-1, Pri=1, Wt=40, Peer=1


Route-1, Pri=2, Wt=60, Peer=4Route-2, Pri=2, Wt=40, Peer=5

Route Group-3





R t M R R ti B d St d d Di t



Client

Target

DSR

Server

DSR

Agent

Agent

1

3

2

4

56

Client

DSR

Server

DSR

Target

DSR

DSR

12

4

5

Client

Target

DSR

Server

DSR

Agent

Agent

12

3

45

Timeout

Request Message Re-Routing – Beyond Standard Diameter

Alternate Routing on Answer

Configurable per Result Code

Alternate routing on transport failure

Connection failure occurs aftermessage 3 has been sent

T-bit set on re-routed message towarn of possible duplicate

Alternate routing on timeout

No response received formessage 2

T-bit set on re-routed message towarn of possible duplicate

3




DIAMETER Mediation

Di t R l E i



Diameter Rules Engine

MME IP Cloud

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HSS FEDiameter

Variant 1Diameter

Variant 2

Mediation and Advanced Routing

Not My Fault Not My Fault

Diameter Mediation via Rules Engine



Diameter Mediation via Rules Engine

Peer

N-1

Peer

N+1

Local

Appl

ART/PRTRoute

List Table

(2) (3)

(4) (5)

DSR

(1)

Request

Answer

Processing

(6) Answer (8) Answer

In-line 3rd

Party App

Off-line

3rd Party App

(4‟)

Conditions logically AND‟d or OR‟d:

• Origin/Destination Host/Realm

presence, value match, partialvalue/range match

• Header fields (Appl-ID, CmdCode,

flags, etc.) value match

• Application specific AVPs

presence, value match, partial

value/range match

Actions:

• Add AVP

• Delete AVP

• Modify AVP• Modify header field

• Route to Local App

• Route to Peer via Route-List

• Send Answer with specified

Result-Code

• Copy message/session

Diameter Rules Engine

trigger points – trigger

one or more tasks, with

priority


Mediation Conditions



Mediation – Conditions

› The DSR must evaluate conditions provisioned by the operator

before attempting to perform mediation

› The conditions can be “ ANDed” and include checking for

Origin-Host/Realm (begins with, ends with, any or exact match)

Destination-Host/Realm (begins with, ends with, any, present, absent

or exact match)

Command Code (exact match or any)

Application ID ( exact match or any)

If the request traversed a certain host (i.e hostname present in route-

record)

If the request includes a certain AVP (check attribute name) If the request does not include a certain AVP (check attribute name)

Ability to check for the value of a certain AVP

And so on…


Mediation Actions Supported



Mediation – Actions Supported

› Add AVP

The Attribute Value can be specified or derived based on anotherattribute value present in the message

› Delete AVP

The AVP code (Attribute Name or free format) is specified by theoperator

• Delete specific instance or all instances

› Modify Header – CC, Appl-ID, Flags› Modify AVP code (Attribute Name)

› Modify AVP flags – Set/Reset/Toggle

› Modify Value of a specific AVP code

The AVP code is specified by the operator

The Attribute Value can be specified or can be derived based on itscurrent value or derived from another attribute value present in themessage




3rd Party Application Support





Peer

N-1

Peer

N+1

PeerRoutingTable

RouteList

Table

(2)

(3) (4)

UpstreamDownstream

DSR

(1)

Request

AnswerProcessing

(5) Answer (6) Answer

In-line3rd Party

Appl

Off-line3rd Party

Appl

Receives a copy ofcomplete Diameter

message and performs

processing

Several options for App

server:

• Redirect server

• Special redirect server

returning encapsulated msg

• B2BUA

• Proxy/Relay (requires

special processing at DSR to

suppress loop detection)

(3‟)


In line App Server as a Special Proxy/Relay



In-line App Server as a Special Proxy/Relay

The DAS routes the original

request, perhaps with

modifications, back through theDSR

The new request (msg #3) has a

new Hop-by-Hop ID

The End-to-End ID is unchangedby the DAS

To prevent loop detection, the

DAS does NOT add DSR to the

“Route-Record” before sending

out msg #3 The DAS must maintain

transaction state and relay the

answer msg #6

DSR

DAS

1

2

3

4

5

6

7

8


In line App Server as a Special Redirect Server



In-line App Server as a Special Redirect Server

This method is used when theDAS wants to drop out of the Answer path

This is a future case, post DSR 2.0

The DAS returns a Redirectresponse with the original,perhaps modified, Request

encapsulated (in a mutuallyagreed AVP)

The DSR extracts theencapsulated Request and routesit, factoring the Ingress Peer (i.e.DAS) into the routing decision

The DAS will not see the Answermsg #5

DSR

DAS

1

2

4

5

3

6


In-line App Server as a B2BUA



In-line App Server as a B2BUA

DAS responds with an Answerto an incoming Request and

originates a new Request

The hop-by-hop id and more

importantly the End-to-End id in

the inbound and outboundRequests are different

The two Requests are only

logically related at the DAS

Supported in DSR 2.0

DSR

DAS

1

2

3

4

5

6

7

8


In-line App Server as a Standard Redirect Server



In-line App Server as a Standard Redirect Server

DAS responds with an

Answer (Result-Code 3006)to an incoming request

The Answer includes a

“Redirect-Host” AVP

indicating the destination

host the message should berouted towards

The DSR uses the contents

of the “Redirect-Host” AVP to

route the Request

Supported post DSR 2.0

DSR

DAS

1

2

4

5

3

6


Off-line App Server



Off-line App Server

DAS receives copy of

Request (1‟) and, optionally,

the associated Answer (4‟)

DSR does not maintain

transaction state for copied

Requests (any Answers

received from DAS are

discarded)

Supported post DSR 2.0DSR

DAS

1

1‟

2

34

4‟




Peer Overload and Flow Control

Remote Congestion Control



Remote Congestion Control

› Peer Transport Congestion Control via the transmit queue

When queue level exceeds a user-configurablethreshold, the transport connection is markedcongested

New Requests must use an alternate route

Answer messages are unaffected› Peer Transport Congestion Control using Answers

Answer contains the DIAMETER_TOO_BUSY Result-Code

Optionally mark connection congested for a user-configurable time

Answer messages are unaffected


Message Throttling



Message Throttling

› To assist with prevention of Diameter peer overload, DSR

provides a method for throttling the volume of DiameterRequest traffic sent to peers based on Request content.

› For example, a registration storm resulting from an HSS failure

could result in the remaining HSS nodes becoming

overloaded.

In this scenario, having the capability to throttle the rate of certain

message types routed to the HSS may effectively prevent the HSS

from becoming overloaded.

Selection of the traffic to be throttled leverages the Peer Routing

Table (PRT) described earlier, allowing a combination of Appl-ID,

Command-Code, Destination-Realm, Destination-Host, Origin-

Realm, and Origin-Host.




Diameter Intelligence Hub

Network Visibility

Diameter Intelligence Hub Features



Diameter Intelligence Hub Features

› Tracing Trace nodal transactions across DSR and between other network elements (e.g., other

DSRs, HSSs, MMEs)

Full decode of Diameter payload Display trace output in ladder diagram

Extensive tracing filters available (e.g., IMSI, SGSN, etc.)

› Data Feed of xDR records NFS and (S)FTP supported

Correlated records can be exported to any external server

› Filtering View actual traffic as xDRs

Filter through traffic to pinpoint issues

› Alarms Alarm forwarding for DIH system alarms via SNMP/email

› Configuration and provisioning

Web-based GUI providing security, configuration, and application access for DIH› Collection and Storage Create and store unique records for each desired transaction (PDUs, xDRs)

52 | Tekelec. For What's Next. Tekelec Confidential



S6/S9 Roaming Proxy (Diameter Edge Agent) LTE/IMS

Use Cases

S6/S9 Roaming Proxy (Diameter Edge Agent)



Roaming

Steering

MAP/Diameter

Interworking

HSS/MME/PCRF

Topology Hiding

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)

Roaming Proxy

LTE/IMS

(S6/S9)


S6/S9 Roaming Proxy (Diameter Edge Agent)

Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

MME Topology Hiding (MME Binding)



MME Topology Hiding (MME Binding)

2) Update-Location-Request

• Origin_Host = MME_Public

• Origin_Realm = Op1.NET

• Destination_Realm = Op2.NET• User-Name = IMSI_1

Current

Serving

MME

Previous

Serving

MME

IMSI

MME1 MME2 IMSI_1


• Origin_Host = MME1


• Destination_Realm = Op2.NET

• User-Name = IMSI_1

Gateway

DSR

MME 1 MME 2

MME <> IMSI

Mapping

HSS

DSR replaces MME ID with genericID and saves the mapping of

IMSI <> Current MME and

Previous MME. Mapping must

be shared with mate(s) as well.


MME Topology Hiding



2) Cancel-Location-Request• Origin_Host = HSS1

• Origin_Realm =Op2.NET

• Destination Host = MME2

• Destination Relam = Op1.NET• User-Name = IMSI_1

3) Cancel-Location-Answer





• Origin_Host = MME_Public



1) Cancel-Location-Request

• Origin_Host = HSS1• Origin_Realm =Op2.NET

• Destination Host = MME_Public

• Destination Relam = Op1.NET


MME Topology Hiding

Gateway

DSRMME 1 MME 2

MME <> IMSI

Mapping

HSS


Current

Serving

MME

Previous

Serving

MME

IMSI

MME1 MME2 IMSI_1

HSS Topology Hiding



HSS Topology Hiding

IMSI HSS

IMSI_1 HSS _1






Gateway

DSR MME 1

HSS 1 HSS 2

3) Update-Location-Answer

• Origin_Host = HSS1




• Origin_Host = HSS_Public







• Destination_Host = HSS1


DSR replaces HSS ID

with generic ID. The

mapping of IMSI <> HSS

is provisioned.


HSS Topology Hiding



HSS Topology Hiding

IMSI HSS

IMSI_1 HSS _1

Gateway

DSR MME 1

HSS 1 HSS 2

1) Purge-UE-Request

• Origin_Host = MME1• Origin_Realm =Op2.NET

• Destination Host = HSS1



1) Purge-UE-Request


• Origin_Realm =Op12NET

• Destination Host = HSS_Public



Roaming Steering



g g


› Assumes operator has preferred roaming partner(s) for LTE roaming, such that it

is desirable for roaming subscribers to attach to the preferred visited network

whenever possible.› It may not be feasible to attach to a preferred network due to limited coverage, in

which case roaming on a non-preferred VPLMN can be allowed.

Roaming Area

Preferred Visited

PLMN

Non-

Preferred Visited

PLMN Allow LTE

roaming if sub is

in preferred

coverage

Prevent sub from

roaming into non-

preferred

networks

Example Flow - Preferred network



p


Non-Preferred

Visited

PLMN

Rules

HSSHome PLMN

DSR

Preferred

VisitedPLMN

MME

MME

eNode B

eNode B

Roaming

Subscriber

Diameter: ULR

Trigger on

Registration

events with

PLMN ID

Event to SubscriberSpecific Rules DB

Using

Subscriber

Profile

PLMN ID

making

Roaming

Decision

DSR to

allow

registration

ULA to HSS

Example Flow - Not a Preferred network



p


Non-Preferred

Visited

PLMN

Rules

HSSHome PLMN

DSR

Preferred

VisitedPLMN

MME

MME

eNode B

eNode B

Roaming

Subscriber

Diameter: ULR

Trigger on

Registration

events with

PLMN ID

Event to SubscriberSpecific Rules DB

Using

Subscriber

Profile

PLMN ID

making

Roaming

Decision

DSR to not

allow

registration

› Registration on non-preferred network can be allowed after configured # of failed attempts

› If there is other Roaming Agreement with the HPMN covering other Radio Access Technology(RAT) it could return a RAT_NOT_ALLOWED (5421) error to the MME

› If there is no Roaming Agreement between HPMN and VPMN it can sendROAMING_NOT_ALLOWED (5004)

USA Tier 1 Operator - MAP-Diameter IWF Use Case



p

SGSN

DRA

GWDRA

SGSN

SGSN

Visited Net Home Net

HAR

S6d

S6d

Gr

S6d

LTE subs

3G subs

AT&T subs

roaming under

3G coverage

3G subs

SRP3G subs

LTE subs

IWF

LTE subs

LTE subs

› DSR will do address resolution on incoming S6d message and direct it to the HLR

for non-LTE capable subs, requiring Diam -> MAP conversion.

› Other use cases will arise.


MAP-Diameter Interworking Function



g

Example – Au thentic at ion request init iated by SGSN for UMTS/GERAN sub

DSRM-D IWF

vSGSN

1) MAP Send_Auth_Info

•Requesting node type = SGSN

SCCP

•CdPA=MGT

•CgPA=SGSN ID

AAAHSS

3) Auth-Info-Request

•Orig-Host=SGSN ID

•Req-UTRAN/GERAN -Auth-Info

4) Auth-Info-Answer

•Orig-Host=HSS ID

• Auth-Info=UTRAN vector

5) MAP Send_Auth_Info ack

• Auth set list=UTRAN vector

SCCP

•CdPA=SGSN ID

•CgPA=HSS ID

1. This covers the case where vSGSN doesn‟t know the HSS for the sub. Assumes the IMSI of the LTE-capable sub

is in a specific range that can be distinguished from non-LTE capable subs. Assumes Requesting node type =

MME/SGSN will not be used.

2. In the SS7 net, MGT or DSR ID can be used to GT route to DSR. It is assumed that IMSI is not sufficient.

3. DSR will be required to do HSS address resolution if necessary.


2) MAP Send_Auth_Info

•Requesting node type = SGSN

SCCP

•CdPA=MGT, IMSI or DSR ID

•CgPA=SGSN ID

6) MAP Send_Auth_Info ack

• Auth set list=UTRAN vector

SCCP

•CdPA=SGSN ID

•CgPA=HSS ID

SS7




g

Example – Cancel location request init iated by HSS for UMTS/GERAN sub

DSR

M-D IWFvSGSN AAAHSS

1) Cancel-Location-Request

•Orig-Host=HSS ID

•Dest-Host=SGSN ID


•Orig-Host=SGSN ID

2) MAP Cancel_Location

SCCP

•CdPA=SGSN ID

•CgPA=HSS ID


4) MAP Cancel_Location ack

SCCP

•CdPA=HSS ID

•CgPA=SGSN ID

SS7

3) MAP Cancel_Location

SCCP

•CdPA=SGSN ID•CgPA=HSS ID

5) MAP Cancel_Location ack

SCCP

•CdPA=HSS ID

•CgPA=SGSN ID




g

Example – Update Location initiated by SGSN

DSRM-D IWF

SGSN

Dialogue Continuation

UpdateGprsLocation

AAAHSS

ULR

ULA

UpdateGprsLocation ack

› “Dialogue Continuation” consists of the exchange of one or more InsertSubscriberData messages if

subscriber data is included in the ULA . If trace data is included in the ULA, the DSR sends an

ActivateTraceMode message to the SGSN.




Policy Proxy 3G/LTE/IMS (Gx/Gxx/Rx/S9)

Use Cases

Policy Network Scaling



Network-wide

PCRF Binding

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)

Policy Proxy

3G/LTE/IMS

(Gx/Gxx/Rx/S9)


PCRF

Topology Hiding

Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Standard 3GPP Diameter Routing Agent (DRA)



› Provides the standard 3GPP DRA

functionality

› Selects PCRF based on a load

balancing algorithm

› Same PCRF (MPE) within one

realm is selected for all user‟s

sessions› Acts by default as a Diameter proxy

with regards to Rx, Gx and Gxx

› Can act as DRA and/or Diameter

base proxy/relay agent based on

routing table configuration


Gxx

GGSN/

PGW

Rx

Gx

PCRFHSGW/SGW

DSR(DRA)

P-CSCF

DSR Policy Scalability & Binding Overview



› The DSR Policy Binding is a

feature capability of the DSR.

The DSR sits between the PCEFand the PCRFs in the network

› DSR Policy Binding Benefits:

Session correlation – The DSR

Policy Binding routes sessions for

the same UE to the same PCRF

Load balancing – The DSR Policy

Binding can balance transaction

load across PCRFs

Scalability – The DSR Policy

Binding allows the PCRFs toscale across sites by adding

hardware


DSR

PCRF PCRF PCRF

PCEF

Site1

DSR

PCRF PCRF PCRF

Site2

DSR Policy Binding Message Flow



1. The DSR Policy Binding receivesa message from a PCEF

2. The DSR Policy Binding makes arouting decision for the incomingmessage

› New UE – route to an PCRF basedon the load balancing algorithm

› Existing UE – route to the PCRF

that is already handling sessionsfor this UE

3. The DSR Policy Binding sends themessage to the appropriate PCRF

4. The PCRF processes themessage and sends the response

to the DSR Policy Binding

5. The DSR Policy Binding sends theresponse to the PCEF

1

32


DSR

PCRF PCRF PCRF

PCEF

Site1

DSR

PCRF PCRF PCRF

Site2

4

5

Policy Binding Across a DSR Pair



› Multiple DSRs serving one

Diameter realm act as one

logical DRA function ensuring

the same PCRF is selected forall user‟s sessions

› DRMA protocol: Diameter

Routing Management

Application – proprietary

Diameter application used for

inter-DRA communication

about load and topology

› Gateway DSRs supportroaming interfaces

› S9 policy/charging roaming

interface support to be added

when needed

Region 2

Region 1

DRMA

PCRF

P-CSCF

P-CSCF

IPX

PGW/

HSGW

PCRF

GatewayDSR

DSR

PGW/

HSGW

DSR

DRA

DRA

To/From Other

Networks

Policy Binding Across Multiple Pairs



Region 2

Region 1› Subscriber Binding Repository

(SBR) added to each DRA to

retain binding information

› SBRs share binding information

with each other in real time

› Gateway DSR can be added to

the DRA pool to optimize S9

routing

DSR

DRA

PCRF

P-CSCF

P-CSCF

IPX

PGW/

HSGW

PGW/

HSGW

DSR

DRA

PCRF

DSR

DSR

GatewayDSR

Region 4

Region 3PCRF

PCRF

P-CSCF

PGW/

HSGW

P-CSCF

PGW/

HSGW

DRA

DRA

Subscriber Binding Repository

Replication

Diameter

Separate DRAs and Core DSRs




Region 2

Region 1

DRMA

S6

› Core DSR nodes support S6a/d

interfaces to support internal

network scalability

› Gateway DSRs support

roaming interfaces

› Separate DSRs deployed to

serve as 3GPP Diameter

Routing Agents (DRA),

dedicated to PCRF binding

function for the network

› Multiple DSRs serving oneDiameter realm act as one

logical DRA function ensuring

the same PCRF is selected for

all user‟s sessions

› DRMA protocol: Diameter

Routing Management

Application – proprietary

Diameter application used for

inter-DRA communication

about load and topology

DSR

DRA

PCRF

P-CSCF

P-CSCF

IPX

PGW/

HSGW

MME

PGW/

HSGW

DSR

DRA

S6

PCRF MME

DSR

To/From Other

NetworksDSR

GatewayDSR

HSS

HSS

DSR Incorporates DRA Functionality




› Core DSR nodes support DRA

function and S6a/d interfaces to

support internal network

scalability

› Gateway DSRs support

roaming interfaces

› Other charging and IMS

interfaces are also supported,

but not shown

› S9 policy/charging roaming

interface support to be addedwhen needed

Region 2

Region 1

DRMA

S6

PCRF

P-CSCF

P-CSCF

IPX

PGW/

HSGW

MME

S6

PCRF MME

GatewayDSR

DSR

PGW/

HSGW

DSR

DRA

DRA

To/From Other

Networks

HSS

HSS

UE attach – PCRF selected



DSR NE

DSRGGSN PCRFRoaming

Agent

Gx CCR

SBR Response

Binding, looks for

existing bind

SBR Query

DSR Selects PCRFGx CCR

Gx CCA

Gx CCA

Gx CCR

Binding Persist Message

Binding found

SBR Response

SBR Query

Gx CCR

Gx CCA

Binding Update

Gx CCA

SBRPGW




HSS Proxy LTE/IMS (S6/Cx/Dx/Sh/Dh)

Use Cases

HSS Access Network Scaling



IMS HSS

Address

Resolution

LTE HSS Address

Resolution

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)

HSS Proxy

LTE/IMS

(S6/Cx/Dx/Sh/Dh)


HSS

Topology Hiding

Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Internal S6a Network without Agents




HSS BE HSS BE HSS BE HSS BEMulti-HSS

› This shows the SCTP/Diametermesh created by just 6 MMEs and

4 HSSs, with 2 front ends per HSS

› Actual networks may have many

more MMEs and HSSs

Single HSS

› This shows a single HSS option

with all data for all subscribers in a

single backend

› Each MME could connect to just 2

front ends in order to partially

reduce the mesh, as shown

› However, HSS FE capacity mustbe hand-managed (e.g. where to

connect the next MME?, what

happens when traffic on one MME

grows disproportionately?, etc.)

HSS BE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

MME MME MME MME MME MME


Simplified S6a/S6d Network



MME MME MME

Operator_N

HSS BE HSS BE HSS BE HSS BE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

HSS

FE

Operator_2

Operator_3Roaming Hub

Provider

MMEMME

MME

MMEMME

MME

MMEMME

MME

HSS

HSS

HSS

HSS

HSS

HSS

HSS

HSS

HSS

Diameter

Agent

Diameter

Agent

Diameter

Agent


Diameter

Agent

Interconnect to

Foreign Realms for

Roaming

Mapping of subscribers

to HSS, if needed.

Diameter Agent

significantly reduces

total number of

connections

Congestion Control

protects HSS

from overloadDiameter

Agent

USA Tier 1 Core Use Case - Regional S6a Architecture



MME


Region 3

Operator_NOperator_1

Roaming Hub

DSR

DSRDSR

FE FE

FE FE

Region 4

Region 1

FE FE

Region 5

Region 2

FE FE

FE FE

DSR

DSR


MME

MME

MME

DSR

DSR

MME

DSR Edge

Agent

DSR

HSS

HSS

HSS

HSS

HSS

HSS

USA Tier 1 Core Use Case



84

SDM segment 2

SDM segment 1

DRA/SLF1 DRA/SLF2 DRA/SLF4

Colorado

SpringsCincinnati

Azusa Southlake Branchburg

DRA/SLF5 DRA/SLF6

DRA/SLF3

Full Mesh DRA network

SDM segment 3

DRA/SLF7 DRA/SLF8

Site 6 Site 7

Full Mesh DRA network

West Area Northeast Area

Midwest Area

DRA Network

South Area

› LTE network experienced rolling outage of HSS Front Ends (NSN-Apertio) triggered by single faulty MME.

› Adding DSR (DRA) to: 1) use message throttling to protect HSS FEs, and 2) use address resolution (SLF)

to split HSS data across new segments and introduce new HSS vendor(s).

HSS Topology Hiding



IMSI HSS

IMSI_1 HSS _1






Gateway

DSR MME 1

HSS 1HSS 2


• Origin_Host = HSS1




• Origin_Host = HSS_Public







• Destination_Host = HSS1


DSR replaces HSS ID

with generic ID. The

mapping of IMSI <> HSS

is provisioned.


HSS Topology Hiding



IMSI HSS

IMSI_1 HSS _1

Gateway

DSR MME 1

HSS 1 HSS 2

1) Purge-UE-Request

• Origin_Host = MME1• Origin_Realm =Op2.NET

• Destination Host = HSS1



1) Purge-UE-Request


• Origin_Realm =Op12NET

• Destination Host = HSS_Public



HSS Resolution for LTE Mobility Management



4. Update-Location-Answer › All fields same as msg3

3. Update-Location-Answer › Origin-Realm= epc.mnc015.mcc234.3gppnetwork.org

› Origin-Host= HSS2

Visited PMN

(MNC=123; MCC=567)

Home PMN

(MNC=15; MCC=234)

1. Update-Location-Request

› Destination-Realm= epc.mnc015.mcc234.3gppnetwork.org

› Origin-Host= MME1

› Origin-Realm= epc.mnc123.mcc567.3gppnetwork.org

› User-Name= 234150999999999

2. Update-Location-Request

› Destination-Host= HSS2

› All other fields same as msg1

vMME DSR

› Initial Update-Location message will contain pre-defined Destination-Realm constructed based on IMSI in the User-Name AVP, according to 3GPP TS 23.003

› DSR performs address resolution on message 1 and inserts Destination-Host associated with the IMSI, which is HSS2

in this example

› Subsequent messages are host routed, since the MME and HSS now know the identity of each other

HSS1

HSS3

HSS2


IMS Subscription Locator Function



Invite

DSR

Scenario 1 – HSS Provides (redirect) SLF Function

Location-Info-Request (Public-ID)

Location-Info-Answer (Server Name= HSS2)


Location-Info-Answer (Destination Server)

Invite

Scenario 2 – DSR Provides (relay) SLF Function

DSR


Location-Info-Answer (Destination Server)


> Less messages

> Reduced delay

> Less HSS and CSCF

processing

S-CSCF

S-CSCF

HSS1 HSS2

HSS1 HSS2




Charging Proxy 3G/LTE/IMS (Rf/Gy/Ro)

Use Cases

Charging Network Scaling



Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)


OCS/OFCS

Session-based

Routing

Charging Proxy

3G/LTE/IMS

(Rf/Gy/Ro)

OCS/OFCS

Topology Hiding

OCS/OFCS

Address

Resolution

Reference Model for 3G Online Charging



OCS

Online Charging

Functions (OCF)


Recharging

Server

OSS – Post

Processing

SystemRo

Ro

Ro

Ro

Gy

Ge

(CAP)

Ga

Re

Rc Rr

Bo

Session

Based

Charging

Function

(SBCF)

Event

Based

ChargingFunction

(EBCF)Rating

Function

Charging

Gateway

Function

AccountBalance

Mgt

Function

MSC

GGSN

SIP AS

Service

Nodes

IMS

MRFC

IMS

Gtwy

Use Case – Offline/Online Charging Network Scaling




Site 1

OFCF OFCF OFCF

PGW GGSN

OFCF OFCF OFCF. . .

SGW

OFCF

Site 2

OFCF OFCF OFCF

GGSN PGW

OFCF OFCF OFCF. . .

SGW

OFCF

DSRCharging Proxy

DSRCharging Proxy

Adding GW/CSCF/TAS

is transparent to OFCFs

Adding OFCFs is

transparent to

GW/CSCF/TAS

Significant reduction

in number of

connections

CSCF/

TAS

CSCF/

TAS

Common/centralized :

OFCF load-balancing Rf network intelligence

Rf troubleshooting

Topology hiding drives

the need for session

stateful routing

GzRf

3G Mobile GGSN - OCS




SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

8 SBCF‟s/Site

8 SBCF‟s/Site

8 SBCF‟s/Site

Enables future

separation of SBCF

and ABMF viaDiameter

interconnect

Addresses connection

limitations at GGSN

Eliminates need for

load balancers in front

of OCS SBCF/ABMF

SBCF/ABMF

SBCF/ABMF

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

GGSN

DSR

DSR



Summary

Tekelec Confidential

Tekelec DSR - A Multi-application Diameter Agent



Scalability and

Connection

Management

Centralized

Routing and

Load Sharing

Network


Failover Models

TCP/SCTP

Interworking

Diameter

Variant

Mediation

Network-wide

PCRF Binding

Roaming

Steering

MAP/Diameter

Interworking

HSS/MME/PCRF

Topology Hiding

IPsec

Core Relay/Proxy

3G/LTE/IMS

(all interfaces)

Policy Proxy

3G/LTE/IMS

(Gx/Gxx/Rx/S9)

Roaming Proxy

LTE/IMS

(S6/S9)

HSS Proxy

LTE/IMS

(S6/Cx/Dx/Sh/Dh)


OCS/OFCS

Session-based

Routing

Charging Proxy

3G/LTE/IMS

(Rf/Gy/Ro)

OCS/OFCS

Topology HidingPCRF

Topology Hiding

HSSOCS/OFCS

PCRF

Agent

GGSN

PGWMME CSCF

Other

Networks

IMS HSS

Address

Resolution

LTE HSS Address

Resolution

HSS

Topology Hiding OCS/OFCS

Address

Resolution

Diameter Network with DSR



Foreign LTE Domain

Home LTE/IMS Domain

Foreign GPRS Domain

ABMF RF

vSGSN

vS4-SGSN

vPCRF

Diameter

Agent

vMME

Diameter

Agent

IP-SM-GW

PGW

OCF

AF

OFCF

Ease of interworking› Mediation of Diameter variants

› SCTP-TCP interworking

› MAP-Diameter interworking

› IPv4-IPv6 interworking

Simple, secure network

interconnect

› Single point of interconnect› Access control

› Topology hiding

Improved network visibility› Generate reports and track KPIs

› Diagnose network problems

› Probeless monitoring

› Auto-config of perf. mgmt. system

› Capture encrytped messages

Simplified addressing› HSS address resolution and SLF

(subscriber mapping to HSS)› Maximizes HSS utilization and

allows for HSS arch flexibility

› Policy DRA for PCRF scalability

› On-line charging addr resolution

SS7

I/S-CSCF

PCRF

P-CSCFMME

EIR AAAHSS

Reduced network complexity› Adding endpoints requires

changes to agent only› Load balancing and

congestion/network mgmt.

handled by agent

DSR

HSS Res SBR




Thank You




Backup Slides


Acronyms




ABMF Account Balance Mgmt. Function

AF Application Function

CSCF Call Session Control Function

DNS Domain Name System

DRA Diameter Routing Agent

EIR Equipment Identity Register

EPC Evolved Packet Core

GGSN Gateway GPRS Support Node

GRX GPRS Roaming eXchange

HSS Home Subscriber Server

IMC Inter-MP Communication

IMS IP Multimedia Subsystem

IPX IP Packet eXchange

IWF InterWorking Function

LTE Long Term Evolution

MME Mobility Management Entity

OCF Online Charging Function

OFCF Offline Charging Function

PCRF Policy and Charging Rules Function

PDN Packet Data Network

PGW PDN GateWay

RF Rating Function

SB Service Broker

SBCF Session Based Charging Function

SCTP Stream Control Transmission Protocol

SGSN Serving GPRS Support Node

SGW Serving GateWay

SLF Subscription Locator Function

SSR SIP Signaling Router

TCP Transmission Control Protocol

TLS Transport Layer Security

UE User Equipment

References



› IETF 3588bis – Diameter Base Protocol

› 3GPP TS 29.272 – Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN)

related interfaces based on Diameter protocol

› GSMA PRD IR.88 – “LTE Roaming Guidelines”

› 3GPP TS 23.003 – UMTS; Numbering, addressing and identification

› 3GPP TR 29.909 – Diameter-based protocols usage and recommendations in 3GPP

› 3GPP TS 33.210 – 3G Security; Network Domain Security; IP network layer security

› 3GPP TS 23.204 – Support of Short Message Service (SMS) over generic 3GPP Internet Protocol

(IP) access

› 3GPP TR 29.805 – InterWorking Function (IWF) between MAP based and Diameter based

interfaces

› 3GPP TS 29.305 – InterWorking Function (IWF) between MAP based and Diameter based

interfaces

› 3GPP TS 23.292 – IP Multimedia Subsystem (IMS) centralized services; Stage 2

› 3GPP TS 23.203 – Policy and charging control architecture

› 3GPP TS 29.109 - “Zh and Zn Interfaces based on the Diameter protocol”

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