LTE Roaming Design and Deploymentd2zmdbbm9feqrf.cloudfront.net/2013/usa/pdf/BRKSPM-2008.pdf · LTE Roaming Design and Deployment BRKSPM-2008 Prakash Suthar, [email protected]

LTE Roaming Design and Deployment BRKSPM-2008

Prakash Suthar, [email protected]

Senior Solutions Architect

mailto:[email protected]

© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKSPM-2008

What is Roaming all about?

3

Mobile Users Perspective

Make my phone work everywhere

Keep my data going, I need more

Make me feel home

Mobile Provider Perspective

Keep my subscribers happy

Grow my business

Show me the MONEY


Topics

2G/3G and LTE Roaming Overview

Roaming Transport Network

2G/3G Roaming Transport (GPRX Exchange)

LTE Roaming Transport (IP Exchange)

LTE Roaming Design

3G/LTE Inter-working Roaming Scenarios

Local Breakout and Home Routed

VoLTE Roaming

LTE Roaming Deployments

Roaming Reference Documents

4

2G/3G and LTE Roaming Overview


GRX GRX

PLMN

PS Core

VPLMN

PS Core

Roaming in 2G/3G Networks

Voice calls handled in the VPLMN

lower delays, optimized routing

Roaming entitlement verified from home HLR

VPLMN

CS Core

HPLMN

CS Core

Other

Network Voice call

Subscription

management

UE

Internet

UE

Data session

Different approach for voice (CS) and data (PS)

Data traffic home-routed to HPLMN

Policy, QoS and service control in the HPLMN

Longer delay for data

6


Roaming in LTE Networks

IPX

VPLMN

HPLMN

LTE/EPC and all-IP evolution brings new challenges

IPX - IP Exchange, HPLMN – Home Public Land

Voice calls handled in the VPLMN

lower delays, optimized routing

Roaming entitlement verified from home HLR

Data traffic routing determined based upon type of services (APN)

Internet APN & delay sensitive Apps can be served locally from VPLMN

Billing & mediation negotiated through IPX providers

QoS is most critical

For VoLTE capable UE, voice call routing (local/home routed) depend upon roaming agreements

7


PDNs

LTE Roaming Scenario Multiple Entities, Different Requirements

Transport

EPC

MME/SGSN SGW

PCRF

Voice Service

CS Net

PGW

EPC

HSS

PCRF

PGW

Local policy

IMS/CS roaming

DNS Diameter

Security

Security

VPLMN IPX/GRX HPLMN

QoS & Policy

Node Selection

Diameter Routing

Security

Transport

Security

IMS

Voice Services

CS Net IMS

R

A

N

U

E

DNS Diameter

DNS Diameter Billing

R

A

N

U

E

Policy

8

Roaming Transport Network


GPRS Roaming Interconnect: Two Alternatives

BG

SGSN

BG

SGSN

GGSN GGSN

Intra-PLMN Backbone Intra-PLMN Backbone

Gi Gp Gi

PLMN A PLMN B

Internet

Inter-PLMN GRX

Backbone

Internet based Roaming

Direct links using public internet

SGSN, GGSN have public IP

addresses

Provides more optimal routing

Concern for QoS, security

Inter-PLMN Roaming

Needs Inter-PLMN GPRS Backbone

QoS, security SLA managed by GRX

provider

GRX provides value added services

SGSN, GGSN can have

public/private IP addresses

ISP ISP

Home

Services

Local

Services

10


GPRS Roaming Exchange (GRX) Dedicated network brokering among roaming providers.

Normally use BGP MPLS VPN network

Provide secured IP transport, SS7, SIGTRAN among roaming Partner

Value added services – MMS, SMS, voice mail etc.

Roaming

Broker

PLMN2 (Visited)

PLMN1 (Home)

GGSN

SGSN

Roam DNS

Roam DNS

BG

BG

PLMN3

SGSN

Roam DNS

BG

GRX

R

R

R

Roaming

Agreement

SLA

SLA

SLA

Roaming

Agreement

Roaming

Agreement

Root DNS

11

GSMA IR.34,40,88


Roaming Transport – IP Exchange (IPX) for LTE

12

IP Exchange


Routing in GRX/IPX Network


GRX/IPX Provider

GRX/IPX Provider

GRX/IPX Provider

EPC-MNO1

EPC-MNO3

EPC-MNO2

L3VPN/Routed Network

L3 VPN/Routed Network

MP-BGP VPN


GRX/IPX provider uses BGP community to advertise/control routes

GRX/IPX provider uses “Hot Potatoes” concept to route traffic to nearest peering point

Roaming Partners control routes learned/advertised at GRX router

QoS is managed among GRX/IPX provider to meet E2E SLA requirements

13

DNS DRA EPC

DNS DRA EPC

DNS DRA EPC

GSMA IR.34,40,88




GRX/IPX Provider

GRX/IPX Provider

GRX/IPX Provider

EPC-MNO1

EPC-MNO3

EPC-MNO2


L3 VPN/Routed Network

MP-BGP VPN


GRX firewall is normally deployed by large service providers

GRX firewall is configured to allow only specific routes

For GRX/IPX transport over public internet, site-to-site VPN is deployed (IPSec will add overhead ~25%)

14

DNS DRA EPC

DNS DRA EPC

DNS DRA EPC

GSMA IR.34,40,88


IP Exchange (IPX) Transport

Layer1,2,3 transport is same in GRX & IPX.

Dedicated GRX peering point with roaming providers/Exchanges (syniverse, Aicent, AMS-IX etc.)

Layer-3 routing to control routes

BGP routing for route control & best path

Dual Stack IPv4 and IPv6 Transport

QoS alignments

Multi Protocol BGP with community filtering

GRX/IPX Providers should not act as a transit.

15

GSMA IR.34,40,88


IP Exchange (IPX) Requirements

HSS – Home Subscriber System, PCRF – Policy Control Charging Function

Different Protocols

Diameter routing (edge, proxy)

IPX Proxy Service

Managed E2E QoS and SLA

Value Added Services

Mediation & billing CDR for all Apps

Different signalling

Diameter (HSS, PCRF)

SIGTRAN for messaging etc.

16

GSMA IR.34,40,88

So what are key difference between GRX and IPX

Can I upgrade my GRX network to support IPX?


IP Exchange (IPX) Proxy Service

Proxy service enable inter-working of different services on bilateral basis

Help to route control & user plane packets

Proxy Services Examples

Session-based accounting including CDR

Implement Black list/White list

Security functions (such as access control)

IPv4 / IPv6 transition/translation

Handle overlapping IP addresses

Media protocol conversion / transcoding

Ability to trace the originator

17

GSMA IR.34,40,88

LTE Roaming Design


LTE Roaming Control & User Plane

Gx, S9, S6a (SCTP, Diameter)

S5, S8 (GTP)

S11 (GTP)

S1-MME (SCTP, S1AP)

Proper routing of control plane message are most crucial to maintain same user experience while roaming

19

S5

S1-U (GTP)


IPX Provider

3GPP Architecture for LTE Roaming (TS 23.401)

All data traffic from visited network is routed to home

Diameter interfaces inter-PLMN: S6a, S6d, S9

2G/3G and LTE interworking

S6a

HSS

S8

S3 S1 - MME

S10

UTRAN

GERAN SGSN

MME

S11 Serving

Gateway UE

“ LTE - Uu ” E - UTRAN

S12

HPLMN

VPLMN

PCRF Gx Rx

SGi Operator’s IP

Services

PDN Gateway

S 1 - U

S4

Home-Routed

20


IPX Provider

3GPP Architecture for LTE Roaming (TS 23.401)

Selectively some APN are routed to home network

Default internet traffic and other delay sensitive Apps and locally broken

Diameter interfaces inter-PLMN: S6a, S6d, S9

2G/3G and LTE interworking

Local Breakout

S6a

HSS

S 5

S3 S1 - MME

S10

GERAN

UTRAN

S G SN

MME

S11

Serving G ateway UE

" LTE - Uu" E - UTRAN

S4

HPLMN

VPLMN

V - PCRF

Gx

SGi

PDN G ateway

S1 - U

H - PCRF

S9

Home Operator’s IP

Services

Rx

Visited operator PDN

S12

21


LTE Roaming with 2G/3G – Design Considerations

LTE is not deployed everywhere – Need to factor different scenarios

Different roaming agreements may be needed for 2G/3G and LTE

LTE-Only

2G/3G-Only

2G/3G and LTE

Different core network capabilities may be available in HPLMN and VPLMN

Gn-SGSN vs. S4-SGSN

SAE Gateway (SGW, PGW, GGSN etc.)

User plane options - GTP vs. PMIP

Voice Options - CSFB vs. VoLTE

22


Multiple Options with S4SGSN

S4-SGSN deployment happen gradually. Roaming design should factor legacy interfaces

S6d or 3GPP-Rel-8 Gr required to enable EPS sessions over S4

– 3GPP Rel-7 Gr would work for PDP Context over Gn/Gp

Both Gn/Gp and S4 can be used towards the GGSN/PGW

HLR/HSS PGW/

GGSN

S4SGSN

HPLMN

VPLMN

MME

SGW

S8 Gp Gr

S4

S3/Gn

S11 S6d or Gr?

Gp or

S4/S8?

S6d

23


Roaming Scenario-1: Roaming Gateways

HPMN only has PGW as the gateway

for roaming, 2G/3G Access via Gp

interface

HPMN has both GGSN and PGW as

the gateway for roaming, 2G/3G

Access via Gp interface

24


Roaming Scenario-2: Roaming Gateways

HPMN has only PGW as the gateway

for roaming, 2G/3G Access via S8

interface

HPMN has both PGW and GGSN as

the gateway for roaming, 2G/3G

Access via S8 or Gp interface

25


Roaming Scenario-3: LTE only on one side

No LTE on visited Network No LTE on Home Network

26


LTE Roaming Diameter Routing Design

GRX /IPX

DIAMETER

ROUTING

AGENT

DIAMETER

EDGE

AGENT

S4-SGSN

MME

V-PCRF

HSS

H-PCRF

V-PLMN H-PLMN

S6a

S6d

S9

S6a

S9

S6dDIAMETER

EDGE

AGENT

DIAMETER

ROUTING

AGENT

Diameter routing is handled by Diameter Edge (DEA) and Diameter Routing Agent (DRA) Diameter Proxy or Relay for multiple applications (S6a, S6d, S9) Node discovery (e.g. find the HSS in the HPLMN) Routing, scalability and availability Easy interoperability (e.g. AVP manipulation) Security, including network hiding and encryption Roaming Steering should be aligned with analogous SS7 mechanisms

27


Diameter Function – Relay, Proxy, Edge

Diameter Edge Agent

Used at edge of network for inter-

service provider diameter routing

Advertises the Relay application

ID to the outer Diameter peers.

Hide topology of service provider.

Make inter PLMN routing is

independent from inner diameter

messages

Edge agent should be able to

relay or proxy all applications

supported by the PLMN to inner

proxies, inner relays or inner

destination agents CER - Capability Exchange Request

CEA - Capability Exchange Answer

28


G

R

X

Node Selection - DNS Discovery of SGW and PGW

PLMN A (V-PLMN) PLMN B (H-PLMN) MCC= 123, MNC = 456

MME

UE

DNS

SGW

HSS

PGW

Attach Request

(IMSI 123456xxxxxxxxx) (VPLMN_ADDR_NOT_ALLOWED, HPLMN service not barred)

NAPTR internet.apn.epc.mnc456.mcc123.3gpp…

PGW_name x-3gpp-pgw:x-s8-gtp

Home

routed MCC/MN

from IMSI DNS resolving APN FQDN

via authoritative DNS for

HPLMN

SGW Discovery via TAI FQDN NAPTR selection criteria

in the MME

S8

S6a

DNS

Create Session Request

Subscriber

of PLMN B

roaming in

PLMN A

Local DNS

of PLMN A

GRX’s DNS is

authoritative for other

domains

29


Roaming DNS Architecture

The VPLMN does not administer the domains of roaming partners – Realms, APN FQDNs, etc. in the HPLMN

GSMA IR.67 defines Inter-PLMN DNS for GPRS, EPC, IMS, etc – .gprs for GPRS, .3gpppnetwork.org for EPC

The DNS Resolver in the vPLMN relies on the Master Root to find the Authoritative DNS for the HPLMN domain

Inter-PLMN DNS with GRX/roaming partners

Inter-PLMN DNS

is required

GSMA IR.67

30

VoLTE Roaming


VoLTE Roaming Framework

32

GSMA IR.65


VoLTE Roaming Scenario-2

33

GSMA IR.65

VoLTE capable UE roam to visited network. During node selection visited SGW resolve to PGW/SSGSN.

Visited PGW/GGSN is anchoring point for VoLTE call. SGi traffic is routed to visited P-CSCF

Visited P-CSCF forward traffic to S-CSCF for home PLMN IMS network

Second leg of VoLTE call is located by home S-CSCF

We need IMS interworking between VPLMN and HPLMN

Local breakout. Using visited P-CSCF and Home S-CSCF



34

GSMA IR.65

VoLTE capable UE roam to visited network. During node selection visited SGW resolve to visited PGW/SSGSN.

Visited PGW/GGSN is anchoring point for VoLTE call. SGi traffic is routed to home P-CSCF by using IPX/GRX transport

Home P-CSCF forward traffic to S-CSCF for home PLMN IMS network.


We do not need IMS interworking between VPLMN and HPLMN

Local breakout. Using Home P-CSCF and S-CSCF



35

GSMA IR.65

VoLTE capable UE roam to visited network. During node selection visited SGW resolve to home PGW/SSGSN.

Home PGW/GGSN is anchoring point for VoLTE call. SGi traffic is routed to home P-CSCF.

Home P-CSCF forward traffic to S-CSCF for home PLMN by using VoLTE Core.


Home routed. Using Home P-CSCF and S-CSCF


Complex VoLTE Scenarios

36

VoLTE signaling (SIP) is exchanged between VPLMN and HPLMN

Media is routed directly. UE need public IP addresses

Inter-working between home VoLTE is must


SMS over SGs in LTE Roaming

37

LTE UE supporting SMS over SG

SMS is delivered LTE access without forcing UE to fall back to overlay 2G/3G accesses.

MME will use SG interface for SMS delivery


Voice over CSFB in LTE Roaming

38

LTE UE supporting voice over CSFB

For voice termination paging is done

over SG interface

UE is redirected to overlay 2G/3G for

voice termination




40

Roaming Requirements

Roaming Design

IPX Provider Selection

Lab Inter-op Testing

Roaming FOA

Roaming Deployments

LTE roaming has topline business

Requirements aligned with standards

Identify gaps (Roaming partner, IPX)

Inter-operability testing

Test, Retest and Test Again

Billing, mediation, correlation

Security compliance

Feedback &

ad

justm

ents

Additio

nal ro

am

ing f

eatu

res


Sunday (23 June)

TECSPM-2003 Cisco Mobile Packet Core (4 Hrs Tectorial) 01:00-05:00 PM

Monday (24 June)

BRKSPM-2010 M2M for Mobility Networks 08:00-09:30 AM

LTRSPM-2002 Implementing Service Provider WiFi (4 Hrs hands on lab) 01:00-05:00 PM

BRKSPM-2001 Deploying Service Provider Wi-Fi 01:00-03:00 PM

Tuesday (25 June)

BRKSPM-2009 Small Cell Technologies 08:00- 09:30 AM

BRKSPM-2002 Design & Deployment of ASR5500 as SAE Gateways 12:30 -2:30 PM

BRKSPM-2008 LTE Roaming Design and Deployment 03:00 -04:30 PM

Wednesday (26 June)

CCSSPM-2002 Emerging Methods for Monetizing 4G Networks 08:30 -09:30 AM

BRKSPM-2004 Unified MPLS transport and synchronization in mobile networks 01:30 -03:30 PM

BSASPM-1012 Mobile Service Provider Smartphone Signaling Challenges 01:30 -02:30 PM

BRKSPM2005 LTE Policy and Charging Control Architecture 04:00 -06:00 PM

Thursday (27 June)

BRKSPM-2007 High Density WiFi networks for Stadiums and Large Public Venues 08:00 -09:30 AM

TECSPM-2001 IPv6 LTE/EPC Design and Migration (4 Hrs Tectorial) 08:00-12:00 PM

BRKSPM-2013 Integrating Satellite RANs and the Mobile Packet Core 10:00 -11:30 AM

BRKSPM-2003 Cisco SON Architecture 12:30 -02:00 PM

CCSSPM-2001 SP WiFi Case Study by Cox Communications 01:00 -02:00 PM

TECSPM-2002 Cisco VoLTE Solutions (4 Hrs Tectorial) 01:00 -05:00 PM

BRKSPM-2006 Monetization Architecture for Service Provider 04:00 -06:00 PM

SP Mobility Sessions

41

https://www.ciscolive2013.com/content/sessionDetail.do?SESSION_ID=12335





















































LTE Roaming References

IR33 GPRS Roaming Guidelines

IR34 Inter-PLMN Backbone Guidelines

IR40 Guidelines for IPv4 Addressing and AS Numbering

IR61 WLAN Roaming Guidelines

IR65 IMS Roaming Guidelines

IR67 DNS/ENUM Guidelines for Service Providers & GRX/IPX Providers”

IR77 Inter-Operator IP Backbone Security Requirements

IR88 LTE Roaming Guidelines

IR92 VoLTE Roaming Guidelines

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