asr5000/5500 platform and support for lte/epc...

ASR5000/5500 platform and support for LTE/EPC network BRKSPM-2888

Aravind Balakrishnan

Network Consulting Engineer

© 2014 Cisco and/or its affiliates. All rights reserved. BRKSPM-2888 Cisco Public

Agenda

1. Evolution and Requirements for LTE

2. Functionality of E-UTRAN and EPC elements

3. EPS bearers and characteristics

4. End-to-End QoS and Policy Management

5. Call Flows

6. Integration of EPS into GERAN/UMTS

7. Inter-RAT Handovers

8. ASR 5x00 Service Offerings

9. Introduction to VoLTE

10.SaMOG – Accessing EPC via non-3GPP RAN

3


What is LTE?

3GPP LTE is the name given to a project within the 3GPP to improve the UMTS mobile phone standard to cope with future technology evolutions

Evolution - LTE

Motivation

– User demand for higher data rates and QoS

– Cost reduction (CAPEX/OPEX)

– Avoid unnecessary fragmentation of technologies for paired and unpaired band operation

– Continuity of competitiveness for the future

Goals:

– Increase peak data rates while lowering costs and improving services

– Improve spectral efficiency and make use of new spectrum opportunities

4

– Integration with other open standards


Low latency

Mobility

Spectrum Flexibility

Coexistence and inter-working with 3GPP RAN

Although an evolution of UMTS, the LTE air interface is a completely new system

The architecture resulting from this work is called EPS and comprises E-UTRAN on the access side and EPC on the core side

Requirements for LTE

5


Evolved Packet System

E-UTRAN consists of a collection of eNodeBs

The mobile packet core consists of 3 nodes – MME, SGW and PGW

The core nodes interact with supporting elements – HSS, PCRF, OCS etc.

6

E-UTRAN

EPC Network

EPS Network


E-UTRAN:

– Co-existence and interworking with 3GPP RAT

– E-UTRAN Terminals should be able to support measurement of, and handover from/to, both 3GPP UTRA and 3GPP GERAN systems

– The interruption time during a handover of real-time and non-real time services between E-UTRAN and UTRAN/GERAN be less than 300 msec and 500 msec respectively

EPC:

– Provide higher data rates, lower latency, high level of security and enhanced QoS

– Support a variety of different access systems (existing and future), ensuring mobility & service continuity between them

– Support access system selection based on a combination of operator policies, user preference and access network conditions

– Provide capabilities for co-existence with legacy systems and migration to the EPS

Requirements: E-UTRAN and EPC

7

Functionality of E-UTRAN and EPC elements


Performs ciphering/deciphering of the user plane (UP) data

IP header compression/decompression and encryption of user data stream

Routing of user plane data towards SGW

Scheduling and transmission of ETWS messages (originated from the MME)

Scheduling and transmission of broadcast information (originated from the MME or O&M)

User P

lane

Role of eNodeB

9

Contro

l Pla

ne

Radio Resource Management

Measurement and measurement reporting configuration for mobility and scheduling

Scheduling and transmission of paging messages (originated from the MME)

Functionally, eNodeB acts as a layer 2 bridge between UE and the EPC

MME selection and load (re)balancing

9


eNodeB: Protocol Stack, Interfaces

10

Control Plane User Plane


Role of MME

11

NAS Signaling and security

Authentication and Authorization

Checking UEs against EIR database

Managing Subscription Profile

Mobility Management

Bearer management

Selection of SGW, PGW, MME and SGSN

Allocation of GUTIs to UEs

Roaming

Support for Single Radio VCC and CS Fallback

Support for SMS via SGs interface

Support for PWS message transmission

Lawful Interception of signaling traffic


MME: Protocol Stack and Interfaces

12

Control Plane


Role of SGW

13

Routing and forwarding

– DSCP marking based on bearer QCI

– Idle mode DL packet buffering and initiation of network triggered service request procedure

Bearer Binding & Event Reporting Function (BBERF)

Terminates interface towards the E-UTRAN

S5/S8 interface based on GTP or PMIP

Mobility anchor for Inter-eNodeB handover

Inter-3GPP handover (terminating S4)

Non-3GPP access

Lawful Intercept

Charging


SGW: Protocol Stack and Interfaces

14



Per-user based packet filtering/inspection (by e.g. deep packet inspection)

SGi termination

DSCP marking based on QCI of EPS bearer

Lawful Interception

Role of PGW

15

IP Anchor point

Accounting

Radius/Diameter based Authentication and Authorization

Act as PCEF

DHCP related functions


PGW: Protocol Stack and Interfaces

16



Key LTE Identifiers

17

IMSI – International Mobile Subscriber Identity

TAI – Tracing Area Identity

GUTI – Globally Unique Temporary Identity ECGI – E-UTRAN Cell Global Identifier

IMEI – International Mobile Station Equipment Identity

IMEISV – IMEI and Software Version Number

EPS Bearers and Characteristics


EPS Bearer Service Architecture

There are three kinds of bearers in LTE:

– Radio bearer

– S1 bearer

– S5/S8 bearer

19


EPS bearer and Bearer types

EPS bearer is a logical aggregate of one or more IP flows (aka SDF)

20

All SDFs within a bearer receive same level of QoS

Bearers can be categorized based on QoS requirements

– Default Bearer

– Dedicated Bearer

TFTs at both UE and PGW are responsible for distributing SDFs between EPC bearers

Dedicated bearers are established when IP flows that require specific packet forwarding treatment are started

Dedicated bearers can be:

– Non-GBR

– GBR

Default bearers are always non-GBR bearers


Characteristics of bearers

Non-GBR Bearer

– May have a MBR

– Has associated ARP and QCI

– Service must be prepared to experience congestion related packet loss

– Can remain established for long periods of time as transmission resources are not reserved

– Precedence of service dropping over service blocking in congestion situation

– Stay up (no reserved resources)

21

GBR Bearer

– Specified GBR and MBR Note: In 3GPP Rel 8, MBR=GBR

– Has associated ARP and QCI

– Service will not experience congestion related packet loss (provided the user traffic is compliant to the agreed GBR QoS)

– GBR bearers are established on demand as transmission resources are allocated and reserved during the admission control function

– Precedence of service blocking over service dropping in congestion situations

– Inactivity timers are used to control air interface and S1 interface to free up resources

QoS and Policy Management


PCRF: Policy Management

Multiple services, each with a different QoS requirement compete for radio and core resources

23

Policy management is critical in three closely-related areas:

– Limiting network congestion

– Enhancing service quality

– Monetizing services

Policy management is carried out on bearers


PCRF Rules

24


QoS Concepts and Parameters

A bearer has 4 QoS parameters

– QCI – QoS Class identifier User Plane treatment

– ARP – Allocation Retention Priority Control Plane treatment

– GBR and MBR for GBR bearers Used for real time services only

– APN-AMBR and UE-AMBR for non-GBR bearers

25

ARP is stored in the subscriber profile (HSS) on a per APN basis and consists of:

– Priority Level – Values 1 to 15

– Pre-emption Capability flag: Enable/Disable (applicable to the bearer that is being established)

– Pre-emption Vulnerability flag: Enable/Disable (applicable to bearers that is already established)

AMBR is stored in the HSS

– For non-GBR bearers only

– Used for rate capping

– APN-AMBR defined per subscriber and APN and known only to the gateway

– UE-AMBR defined per subscriber and known to both gateway and RAN


QoS in Radio and Transport

QoS need to be maintained in Radio and transport domains

RRM QoS

– QoS Class differentiation via QCIs

– Rate capping via UE-AMBR

Transport QoS

– DSCP marking on IP layer

– Ethernet priority bits (IEEE 802.1p) and/or VLAN ID's (IEEE 802.1q) are used on Ethernet layer

26


End-to-End QoS

LTE supports “end-to-end” QoS

Traffic Flow Template (TFT) consist of:

– Identifier of the packet filter

– Precedence of the packet filter

– Direction – UL/DL

– Filter (Eg: Pattern matching on IP 5-tuple, optional DPI)

27


Standardized QCI characteristics

28

Source: 3GPP TS 23.203

LTE Call Flows


Initial LTE Attach – Slide 1/3

30

Establish RRC connection

Initial Attach Request Download Auth vectors

Authentication Procedure

Agree on integrity and ciphering algorithms



31

Download UE subscription profile

Interact with policy control server

Interact with online charging server

Allocate PDN IP address and accept the connection

Based on UE subscription profile and local policy, initiate establishment of PDN connection



32

Allocate GUTI and accept the Attach

Notify SGW of the eNodeb FTEID

Update HSS with the name of the APN, PDN IP and PGW IP


Detach from LTE

33

Integration of EPS into existing GERAN/UMTS


Initial overlay deployment

35


Inter-RAT via Gn/Gp

36


Mobility: LTE UTRAN/GERAN

Cell Reselection:

– LTE to UTRAN/GERAN – UE sends RAU

– UTRAN/GERAN to LTE – UE sends TAU

SRNS Relocation and Handover:

– LTE to 3G – Source eNodeB sends HO Required (Target RNC ID) to Source MME

– 3G to LTE – Source RNC sends Relocation Required (Target ID=RNC ID) to Source SGSN

37


GUTI to P-TMSI mapping

The mapping of the GUTI shall be done to the combination of RAI of GERAN/UTRAN and the P-TMSI:

– E-UTRAN <MCC> maps to GERAN/UTRAN <MCC>

– E-UTRAN <MNC> maps to GERAN/UTRAN <MNC>

– E-UTRAN <MME Group ID> maps to GERAN/UTRAN <LAC>

– E-UTRAN <MME Code> maps to GERAN/UTRAN <RAC> and is also copied into the 8 most significant bits of the NRI field within the P-TMSI

38


P-TMSI to GUTI mapping

The mapping of P-TMSI (TLLI) and RAI in GERAN/UTRAN to GUTI in E-UTRAN shall be performed as follows:

– GERAN/UTRAN <MCC> maps to E-UTRAN <MCC>

– GERAN/UTRAN <MNC> maps to E-UTRAN <MNC>

– GERAN/UTRAN <LAC> maps to E-UTRAN <MME Group ID>

– GERAN/UTRAN <RAC> maps into bit 23 and down to bit 16 of the M-TMSI

– The 8 most significant bits of GERAN/UTRAN <NRI> map to the MME code

– The P-TMSI signature is sent intact to the MME E-UTRAN <MNC> maps to GERAN/UTRAN <MNC>

39


LTE to UMTS Handover – Slide 1/2

40

Target SGSN retrieves the context of UE from source MME

Lets MSC know that the UE is no longer attached to this MME

Notifies the policy server of new RAT


LTE to UMTS Handover – Slide 2/2

41

Downloads the UE credentials

Accept the RAU Update the PDN connection with UMTS QoS


UMTS to LTE Handover – Slide 1/2

42

Target MME retrieves the context of UE from source SGSN

OI=0 and new PGW TEID makes SGW send MBR to PGW


UMTS to LTE Handover – Slide 2/2

43

Download UE LTE subscription

Update MSS that the UE is Attached to LTE

Update the bearer with LTE QoS


Inter-RAT via S3/S4

44

Cisco ASR 5x00 Service Offerings


ASR 5x00 Series Product Evolution

46


Services/Functionality Supported On ASR 5x00

47


Cisco MME differentiation

Heuristic Paging

Signaling – Congestion Control, Load Rebalancing, Attach Rate Throttling, Diameter throttling on S6a

MSC selection using DNS and fallback to alternate MSC on failure to reach selected MSC

Operator CLI command to place one or more MSC servers in maintenance mode (from an Sv perspective)

Support for MSC server pooling for Sv interface

Dynamic GTP echo

Adaptive TAI

MME Restoration

48


Cisco SGW differentiation

Intelligent paging for ISR

DDN throttling for Pre-Rel 10 MMEs

LIPA optimizations

Traffic policing

802.1p marking in addition to DSCP marking

ICSR – Inter-Chassis Session Recovery

Dynamic GTP echo

49


Cisco PGW differentiation

Virtual APN

Local policy for Gx and Gy

Modular P2P detection, DPI, NAT and Firewall

Throttling – GTP, Gx and Gy

Overcharging protection for 3G and 4G

SAE-GW – Collocated SGW/PGW with increased capacity

802.1p and MPLS experimental bits marking

ICSR – Inter-Chassis Session Redundancy

ICSR/SR enhancements for VoLTE

GTP based S2a and S2b

NEMO support

50


ASR 5000 EPC Service Configuration

MME+SGW+PGW

MME+SGW and PGW

MME and SAE-GW

MME, SGW and PGW

51

MME

+

SGW

+

PGW

MME

+

SGW

PGW

SAE-GW MME PGW MME SGW


Methods to deliver Voice and SMS

VoLGA – Voice over LTE Generic Access

CSFB – Circuit Switch Fall Back

VoLTE – Voice over LTE

53


VoLTE – Voice over LTE

54


SIP Call Origination and Setup

55


SIP Call Disconnect

56

Mobile Offloading


Mobile Offloading

Mobile data offloading is the use of complementary, cheaper and more localized network technologies for delivering data originally targeted for cellular networks

Offloading reflects the carriers desire to strike a balance between encouraging more data usage, while easing traffic from airwaves

WiFi and femtocell technologies are the primary technologies used by the industry

EPS supports the use of non-3GPP IP access networks to access the EPC

WiFi could be trusted or untrusted

58


SaMOG – S2a Mobility Over GTPv2

SaMOG provides EPC Access over trusted WLAN

Why SaMOG?

– Efficient use of spectrum

– Network based mobility

– Seamless mobility between 3GPP and WLAN for EPS services with IP address preservation

– Non-seamless WLAN offload

59


SaMOG Components and Reference Model

60

SaMOG Components SaMOG Reference Model


STa Reference Point

TWAN provides the following information to 3GPP AAA server:

– An indication on whether the TWAN supports S2a, non-seamless offload or both

– The SSID selected by the UE to access the TWAN

3GPP AAA server provides TWAN with:

– Whether access to EPC is allowed for the UE on the TWAN

– Default APN used for EPC access

– Subscriber MSISDN

61


TWAN: Protocol Stack

62

Control Plane for Tunnel Mgmt. User Plane


Network Architecture

63


SaMOG: 3GPP Rel 11

The key requirement of 3GPP Rel 11 SaMOG is to keep standard Rel 11 UEs unmodified with respect to Rel 10 or Pre-Rel 10 UEs

The above requirement leads to several limitations:

– Lack of IP address preservation (no IP mobility)

– Terminal cannot indicate an APN when connecting to the WLAN (the terminal is connected to default APN pre-configured on the TWAG or in the service profile on AAA/HSS)

– Terminal cannot establish multiple connections to multiple PDNs

– Terminal cannot access simultaneously resources in the WLAN and the EPC

64


SaMOG: 3GPP Rel 12

The restriction on modification to the UE imposed by 3GPP Rel 12 of SaMOG definition has been removed

With the removal of the above restriction the following additional functionalities becomes possible:

– Multiple simultaneous PDN connections including concurrent connections via 3GPP access and over WLAN

– PDN Connectivity to EPC over Trusted WLAN concurrent with non-seamless WLAN offload (NWSO)

– IP address preservation for a single PDN connection

– UE is capable of signaling the requested APN over Trusted WLAN

65


Initial Attach in WLAN on GTP S2a – Slide 1/2

66


Initial Attach in WLAN on GTP S2a – Slide 2/2 Scenario A

67


Initial Attach in WLAN on GTP S2a – Slide 2/2 Scenario B

68


Reference

69


Call to Action…

Get hands-on experience with the following Walk-in Labs

MIL1413745: ASR5K/ASR5500 CLI and Tools

Meet the Engineer

Jan 29, 2014 – 4:30 pm to 6:00 pm

Jan 30, 2014 – 4:00 pm to 6:00 pm…

Discuss your project’s challenges at the Technical Solutions Clinics

Attend one of the Lunch Time Table Topics, held in the main Catering Hall

Recommended Reading: For reading material and further resources for this session, please visit www.pearson-books.com/CLMilan2014

CL365 -Visit us online after the event for updated PDFs and on-demand session videos. www.CiscoLiveEU.com

71

http://www.pearson-books.com/CLMilan2014



http://www.ciscoliveeu.com/


Call to Action…

Visit the World of Solutions:-

Cisco Campus

Walk-in Labs MIL1413745: ASR5K/ASR5500 CLI and Tools

Technical Solutions Clinics

Meet the Engineer Jan 29, 2014 – 4:30 pm to 6:00 pm

Jan 30, 2014 – 4:00 pm to 6:00 pm…

Lunch Time Table Topics, held in the main Catering Hall

Recommended Reading: For reading material and further resources for this session, please visit www.pearson-books.com/CLMilan2014

72





Complete your online session evaluation

Complete four session evaluations and the overall conference evaluation to receive your Cisco Live T-shirt

Complete Your Online Session Evaluation

74

asr5000/5500 platform and support for lte/epc...

Documents