MPLS in Mobile Backhaul

MPLS in Mobile Backhaul

MR-234 Issue 2

May 2010 Luyuan Fang Broadband Forum Ambassador Cisco Systems

Doug Hunt Broadband Forum Ambassador Alcatel-Lucent

2

Agenda

1.  Introduction to the Broadband Forum 2.  MPLS in Mobile Backhaul

  Issues, trends and enablers of the transition to IP/MPLS in evolving backhaul architectures

3.  MPLS Basics   MPLS fit and operation in the mobile backhaul network and the

support of end-to-end SLAs, QoS, and high availability features 4.  MPLS Pseudowires

  For legacy network migration (TDM and ATM), LTE support (IP/Ethernet) and their operation in MPLS backhaul networks

5.  MPLS OAM and Protection   Operations, Administration and Management (OAM) capabilities of IP/

MPLS backhaul networks 11.  Packet Synchronization and Timing 12.  MPLS Mobile Backhaul Initiative – MMBI 13.  Summary

3

MPLS in Mobile Backhaul Tutorial Contributors

  Matthew Bocci – Alcatel-Lucent   Rao Cherukuri – Juniper Networks   Dave Christophe – Alcatel-Lucent   Sultan Dawood – Cisco Systems   Doug Hunt – Alcatel-Lucent   Fabien Le Clech – France Telecom   Drew Rexrode – Verizon   Nikhil Shah – Juniper Networks   Dave Sinicrope – Ericsson

4

We are the United Broadband Forum http://www.broadband-forum.org

  The Broadband Forum is the central organization driving broadband solutions and empowering converged packet networks worldwide to better meet the needs of vendors, service providers and their customers.

  We develop multi-service broadband packet networking specifications addressing interoperability, architecture and management. Our work enables home, business and converged broadband services, encompassing customer, access and backbone networks.

5

The BroadbandSuite Goals and Focus

The BroadbandSuite is broken down into three major domains:   BroadbandManagement

–  Goal – enhance network management capabilities and enable an intelligent, programmable control layer that unifies diverse networks

–  Focus - empower service providers to deliver and efficiently maintain personalized services that enhance the subscriber experience

  BroadbandNetwork –  Goal - establish network architecture specifications to support current

and emerging services and applications –  Focus - deliver access, aggregation and core specifications that

provide inherent interoperability, quality, scalability and resiliency capabilities from end-to-end

  BroadbandUser –  Goal - Define unified networking standards by establishing a common

set of CPE capabilities within the business, home and mobile environments

–  Focus - Simplify the service delivery process by developing common devices’ identification, activation, configuration and maintenance specifications

broadband-forum.org

6

Broadband Forum Scope

PARTNER APPLICATION

FUNCTION

PARTNER CONTROL FUNCTION

IDENTITY

BILLING

OSS TR-126 IPTV Quality of Experience

TR-176 DSL Profiles for IPTV

Quality of Experience TR-069 (CWMP)

Identity, Accounting and Policy Operations and Network Management

DSL Quality Management

TR-069 ACS Management

CWMP TR-069

Edge Aggregation

Content Network

VoD

TV

SIP

Multi-Service Core Access

Mobile Network

BS

C

RN

C

SG

W

P2P E-FTTx

GPON

EPON

DSL

Multi Service Architecture & Requirements Certification, Test and Interoperability

TR-101, TR-156 Ethernet

Aggregation

Network TR-144 Multi Service Requirements

IP/MPLS

broadband-forum.org

7

We don’t work alone Coordinated industry efforts maximize value with minimum overlap

broadband-forum.org


Issues, trends and enablers of the

transition to IP/MPLS in evolving backhaul

architectures

9

State of the Market

  Voice and text messages drive majority of current revenue –  Price competition –  Reduction or flattening of growth in

minutes per subscriber in markets such as North America

–  Subscribers granted ability to customize phones

  Initial 4G (LTE/WiMAX) trials/deployments –  Significantly expand data capacity to enable new devices,

services and applications ARPU growth –  1st generation wireless network built as a data network –  Focus on reducing cost per bit

Declining average revenue per user (ARPU)

10

Requirement: DL: 100 Mbps UL: 50 Mbps

DL: 153 kbps UL: 153 kbps

DL: 2.4 Mbps UL: 153 kbps

DL: 3.1 Mbps UL: 1.8 Mbps

DL: 3.1-73 Mbps UL: 1.8-27 Mbps

Evolution to LTE is all about services

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

CDMA2000 1X

EV-DO Rev A

EV-DO Rev B

CDMA2000 1xEV-DO

Broadband data VOD, MOD

High-speed Internet

Enterprise applications

Voice High-speed data Picture/Video

Email Web browsing

Real-time apps

Video telephony, VoIP,PTx,

Interactive gaming,

Multimedia

Broadband Real-time Applications

Multimedia, VoIP, Video Delivery,

Advanced IMS



DL: 1.8-7.2 Mbps UL: 384Kbps

GSM GPRS

HSDPA Rel 5

UMTS (W-CDMA) R99


EDGE

DL: 7.2 Mbps UL: 5.2 Mbps

HSUPA Rel 6

Target: DL: 40 Mbps UL: 10 Mbps

LTE HSPA+ Rel 7

Phase 2

HSPA+ Rel 8

Phase 1

CDMA

WCDMA

Services

IP/Ethernet TDM (SONET/SDH, PDH) FR, HDLC, ATM/IMA

TRANSPORT

Requirement: DL: 100 Mbps UL: 50 Mbps

LTE

11

Data revenue for mobile operators

  Mobile Data revenue (as % of total ARPU) is growing   Mobile broadband data traffic is growing much faster than

corresponding revenue growth

12

From 2G/3G to LTE: Towards all-IP, simplified network architecture

Evolved Packet Core = end-to-end IP transformation of mobile core

New, all-IP mobile core network introduced with LTE   End-to-end IP   Clear delineation of control plane and data plane   Simplified architecture: flat-IP architecture with a single core

What is EPC ?

LTE+EPC

eNode B (eNB)

IP channel

CDMA / EVDO

GSM / GPRS

EDGE

UMTS

HSPA

Evolved Packet Core

(All-IP)

IP channel Packet Switched

Core

PSTN

Other mobile

networks

VPN

Internet

Voice

Channels

GGSN HA

SGSN PDSN

MGW

MSC

BSC / RNC

Circuit Switched Core (Voice)

BTS

Node B

Softswitch GMSC

2G/3G

Transport (backhaul and backbone)

Broadband Forum focus areas for backhaul

13

State of market : LTE

 Large number of cell sites will support mix of 2G, 3G and 4G (LTE/WiMAX) RAN types

 Worldwide LTE subscribers will cross 200 millions by 2014 Source: Infonetics, Q3. 2009, ABI research

14

Backhaul connections Growth (By Technology Type)

Source: Infonetics, 2008

  Operators migrating mobile backhaul to converged, packet-based architectures

  Microwave used extensively in Europe and Asia

Worldwide Mobile Backhaul New Connectivity by Technology

 Multiple options for backhaul transport

 Varies based on geography, availability, volume, inter/ intra carrier relationships

15

Business and technical Drivers for Mobile backhaul evolution

 Expense of the Mobile backhaul is sizable portion of overall OPEX of Mobile operator

 Fix the legacy backhaul bottleneck (Scale)  Solution need to support co-existence of 2G, 3G

and 4G base stations on the same cell site.  Future Proof: Path to 4G, Next Generation

Networks  Address network synchronization

16

LTE Deployment requires evolution of backhaul transport

  LTE is built on an all-IP flat architecture – compared to 3G and previous generations of mobile technology it has

–  A more direct data and control path between the mobile user and the core network

–  Base stations (called eNBs) with additional functionality – including direct communication of client data and control plane traffic between eNBs

  Transport Implications –  Favors more flexible backhaul mesh, such as architectures that do not need to

transverse the aggregation points –  To support transport of latency-sensitive traffic between eNBs, need a backhaul

architecture that minimizes latency –  MPLS at the aggregation points is one of the likely solutions to this challenge

LTE+EPC

eNB

IP channel Evolved Packet Core

(All-IP) Transport (backhaul

and backbone)

eNB

17

LTE Deployment requires evolution of backhaul transport (continued)

  Flatter IP architecture requires smooth interworking between previously separate mobile backhaul and backbone transport networks

–  VPN scaling: LTE enabled eNB user plane by-passes RNC, connects directly to PS-Core

–  Scope of E2E network planning, traffic engineering, transport SLA monitoring increases (e.g. high availability, stringent E2E QoS is no longer broken up into segments with mobile NEs between each)

LTE+EPC

eNB

IP channel Evolved Packet Core

(All-IP) Transport (backhaul

and backbone)

eNB

18

 MPLS is THE unifying technology for various backhaul types

 MPLS is proven in Service Provider deployments globally – it delivers on its promises

 MPLS adds carrier-grade capabilities –  Scalability - millions of users/end points –  Resiliency - high availability including rapid restoration –  Manageability – ease of troubleshooting & provisioning –  Traffic Engineering plus QoS – predictable network behavior –  Multiservice – support for 2G, 3G ATM and IP RAN (e.g. LTE,

WiMAX) and co-existence with other types of traffic e.g. residential

–  Virtualization – VPNs to ensure separation of OAM from signaling / bearer planes, partitioning of multi-operator traffic

Why MPLS?

19

  Backhaul requires co-existence of multiple transport options –  MPLS is proven mechanism to support ATM, TDM, Ethernet, HDLC emulation

(Pseudowires) –  Allows legacy RAN equipment to continue to be utilized (CAPEX protection)

while leveraging the advantages of new packet transport networks   Packet Backhaul needs to support multi-media traffic

–  Voice/VoIP, Video, SMS, –  MPLS –TE enables advanced QoS capability –  Improved network utilization, Better ROI

  Reliability is critical –  MPLS offers faster convergence and interoperable mechanisms for failure

detection and recovery   Backhaul is increasingly becoming a strategic asset

–  MPLS at cell site enabled carriers to offer new revenue generating services (i.e. L2/L3 VPNs)

Why IP/MPLS in Mobile Backhaul?

Scalability

IP/MPLS

Resiliency Multi-Service Manageability TE/QOS

20

IP/MPLS Backbone Radio Access Network

Multi-phase MPLS migration into RAN Transport

Hub Cell Site

2G – TDM/IP 3G – ATM/IP

Phase 1

WiMAX - Enet

MPLS “edge”

MTSO

Converged IP/MPLS

Backbone

TDM/IP ATM/IP Enet

BSC RNC WAC

TDM ATM PPP Enet µwave (PDH channels)

Separate transmission facilities for different

technologies

ATM T1/E1

Copper

PPP T1/E1

Copper

TDM T1/E1

Copper

Enet/PPP T1/E1

Copper

Central Aggregation, Consolidation,

Service Routing

LTE - Enet

Aggregation via

SDH/SONET

ATM Aggregation

Overlay

TDM PPP SDH/SONET

Fiber

ATM Enet

TDM PPP ATM Enet µwave (SDH ch)

Enet Fiber

21



Hub Cell Site


Phase 2

WiMAX - Enet

MPLS Aggregation

for all Technologies

MPLS Ethernet ch µwave

MPLS Ethernet

fiber

MPLS “edge”

MTSO

Converged IP/MPLS

Backbone

TDM/IP ATM/IP Enet

BSC RNC WAC

MPLS SDH/SONET

fiber

TDM ATM PPP Enet µwave (PDH channels)

Separate transmission facilities for different

technologies Common facility for

all traffic

TDM PPP ATM Enet

TDM PPP ATM Enet

TDM PPP ATM Enet

ATM T1/E1

Copper

PPP T1/E1

Copper

TDM T1/E1

Copper

Enet/PPP T1/E1

Copper

Central Aggregation, Consolidation,

Service Routing

LTE - Enet

22



Hub Cell Site


Phase 3

WiMAX - Enet

MPLS “edge”

MTSO

Converged IP/MPLS

Backbone

TDM/IP ATM/IP Enet

BSC RNC WAC

Router

TDM ATM MPLS

Ethernet ch µwave

Enet

TDM ATM MPLS

Ethernet fiber

Enet

TDM ATM MPLS

SDH/SONET fiber

Enet

Common facility for all traffic

TDM MPLS

Ethernet ch µwave

Enet

TDM MPLS

Ethernet fiber

Enet

TDM MPLS

SDH/SONET fiber

Enet

Common facility for all traffic

IP

IP

ATM

ATM

IP ATM

MPLS Aggregation


MPLS Aggregation


IP/MPLS is agnostic to transmission techniques in Access

LTE - Enet

23 23

Mobile Backhaul Standards Landscape

  3GPP –  RAN definition and specification – definition of the RAN and its interfaces

  Broadband Forum –  MMBI – architecture of mobile backhaul transport support with MPLS –  WT-145 – next generation broadband network architecture to support

mobile backhaul –  Certification – certification of MPLS technologies to support mobile

backhaul transport –  Tutorials and Marketing – education on MPLS in mobile backhaul

transport and issues   Metro Ethernet Forum

–  MBH Phase I and II – Metro Ethernet services and interfaces required to support mobile backhaul

–  MBH Marketing and Tutorial – education on Ethernet in mobile backhaul transport and issues

  ITU-T SG 15 –  Adaptive & Differential Clock Synchronization specification

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What is MMBI ?

  MPLS in Mobile Backhaul Initiative –  Work item embraced by the Broadband Forum –  Defining role IP/MPLS technologies in Mobile backhaul

(including LTE)

  IP/MPLS Forum launched the industry wide initiative in 2Q 2007 and the Broadband Forum continues that work –  Framework and Requirements Technical Spec: IP/MPLS

Forum 20.0.0 –  Detailed technical specs are ongoing work –  MPLS in Mobile Backhaul Certification Program

  Pilot phase on TDM over MPLS complete   ATM over MPLS in development   Ethernet and IP over MPLS (future work item)

25

What MMBI aims to solve/facilitate ?

  Faster mobile broadband deployment –  HSPA/HSPA+/LTE, EV-DO, LTE

  Enhanced experience for mobile users with new data services and application, along with voice –  Location based service, VoIP, gaming, etc

  Future-proof investments   Improve mobile operator’s bottom line and simplify

operations –  Converging technology specific backhaul networks to single

multi-service packet infrastructure –  Based on proven benefits of IP/MPLS while leveraging cost-

benefits of Ethernet

26

MMBI Reference Architecture (more on this later)

Terminology WCDMA/ UMTS

CDMA 2000/1x LTE

Base Station Node-B BTS eNB Base Station Controller RNC BSC A GW

Circuit Edge devices MSC MSC - Packet Edge devices SGSN, GGSN PDSN PDN GW

Technology Data Services GSM/UMTS EDGE, GPRS, HSPA

CDMA CDMA2000, 1xRTT, EV-DO

4G LTE

HDLC TNL

HDLC TNL

Mobile Aggregation Site Gateway

IP TNL

ATM TNL TDM TNL

IP TNL

ATM TNL

TDM TNL

Aggregation network

BS Access Aggregation

Access network xDSL,

microwave, Leased

Line, GPON,

Optical Eth

Access Node

Cell Site Gateway

Edge Node IP/

MPLS Core

mobile networ

k

Core

Iur

Abis A

Iub

Iub/S1

Iub

RC

Iu-CS Iu-PS

MPLS transport network

Gb Iu-PS

Iu-CS A Gb Abis MSC 3G

SGSN 3G

SGSN 2G

MSC 2G

Abis Abis

Edge Node

Edge Node

Edge Node

Iub/S1

S5/S8A

MPLS PE function could be integrated into the BS (BTS/Node B/BS)/RC

PDN GW

S5/S8A

RAN

MPLS Basics

MPLS operation in the mobile backhaul network

Support of end-to-end SLAs, QoS, and high availability

features

28

MPLS Definition

  Multiprotocol Label Switching (MPLS) is a network technology that enables network operators to implement a variety of advanced network features, both to serve their customers and to enhance their own network utilization.

  These features are a result of the transformation of the connectionless per-hop behavior of an Internet Protocol (IP) network into a connection-oriented forwarding along MPLS Label Switched Paths (LSP).

  MPLS operates over a range of devices such as routers, switches, etc, using enhanced IP protocols and leveraging Operations Administration and Management (OAM) systems similar to those with IP –  MPLS can be viewed as an extension of IP, rather than its

replacement.   MPLS works with both IPv4 and IPv6   MPLS is currently being extended to provide additional packet

transport capabilities (MPLS-TP)

29

Label Switched Path (LSP)

 LSP is the path followed by labelled packets that are assigned to the same FEC

–  Packets of similar characteristics are treated/forwarded in a similar way

LSP

IP source network

IP destination network

MPLS network

  FEC is Forwarding Equivalence Class –  This class is formed based on the equivalence in forwarding,

•  i.e., “forwarding equivalence” FEC-to-label binding mechanism –  Flow (stream, traffic trunk) of IP packets – forwarded over same LSP –  FEC-to-label binding mechanism binding is done once, at the ingress

30

Network Engineering vs. Traffic Engineering

  Network Engineering –  "Put the bandwidth where the traffic is"

 Physical cable deployment  Virtual connection provisioning

  Traffic Engineering –  "Put the traffic where the bandwidth is"

 On-line or off-line optimisation of routes  Ability to diversify routes

–  Leverage knowledge of available resources in network

31

Providing Resiliency with MPLS

 Lower Layers –  Partial or full mesh –  Automatic Protection Switching strategies of SONET/

SDH/WDM

 MPLS Layer –  Outage

  Protection and Re-routing procedures –  Administrative

  Re-optimization and Preemption

 IP Layer –  IGP convergence algorithms

IGP: Internal gateway protocol

32

Carrier-Grade IP/MPLS Protection

  Restoration time –  Recovery times smaller than IGP convergence times. 50ms fail-over

possible. –  Failover transparent to edge service protection mechanisms

  Resource efficiency –  Leverages statistical gains over use of optical or SDH/SONET layers

  Service differentiation –  MPLS enables granular levels of protection. This helps service

differentiation (QoS, protection)   Node protection

–  Service awareness assist in node protection or protection of layer 2 traffic

  Robustness –  Route pinning avoids transient LSP behavior when SPF routing

changes   Interoperability

–  MPLS provides standardized protection in multi-vendor environments –  RFC 4090: FRR extensions to RSVP

MPLS Pseudowires

For legacy network migration (TDM and ATM), LTE support (IP/Ethernet)

and their operation in MPLS backhaul networks

34

What is PWE3?

 PWE3 – “Pseudowire Emulation Edge-to-Edge” – IETF Working Group assigned to study carriage of “Legacy and New Services” over MPLS

 Protocol encapsulations can be carried over MPLS –  Legacy Services under consideration are:

  FR, ATM, SONET & SDH, DS0, DS1, DS3, …

–  And new services such as:   Ethernet, VLANs, etc.

35

MPLS Pseudowire Reference Model

AC: Attachment Circuit CE: Customer Edge PE: Provider Edge

PE2 CE2

MPLS Tunnel LSP (forward)

MPLS Tunnel LSP (backward)

Pseudowire (PW) (forward)

Pseudowire (backward)

Native Emulated Service

CE1 PE1 IP/MPLS Network

ATM, Ethernet , FR, IP, TDM, etc Attachment Circuit (AC)

- Same at each end

AC AC

36

MPLS Point-to-Point Services Label Stacking

  Three Layers of Encapsulation 1)  LSP Tunnel Header: Contains information needed to

transport the PDU across the IP / MPLS network 2)  Pseudowire Header: Used to distinguish individual PWs

within a single tunnel 3)  Emulated VC Encapsulation: Contains the information about

the enclosed PDU (known as Control Word)   LSP Tunnel Header determines path through network   Pseudowire Header identifies VLAN, VPN, or

connection at the end point   All services look like a Virtual Circuit to MPLS network

Tunnel Header

PW Header Layer 2 payload

VC Encaps Information

1 2 3

37

Layer 2 Encapsulation - PWE3

 Ethernet  RFC 4448

 ATM cell and ATM AAL5  RFC 4717

  TDM  RFC 4553 (structure agnostic)  RFC 5086 (CES0PSN)

 PPP/HDLC  RFC 4618

3G R99/R3 UMTS

2G to 3G

3G to 4G (LTE/WiMax)

CDMA

38

  Enables transport of an Ethernet/802.3 PDU across a MPLS network   Ethernet PDU consists of the Destination Address, Source Address, Length/Type,

MAC Client Data and padding   Ethernet PW operates in one of two modes:

–  Raw mode: If there is a 802.1Q VLAN tag in a frame, it is passed transparently by network –  Tagged mode: Each frame must contain at least one 802.1Q VLAN tag which PW termination

points have an agreement (signaled or manually configured) on how to process tag   Optional Control Word allows:

–  Sequence number to guarantee order of frames – use is optional

Control Word (use is optional)

RFC 4448

Encapsulation Methods for Transport of Ethernet over MPLS Networks

Tunnel Header

PW Header

4 octets 4 octets Control Word

4 octets

0000 Reserved

bits 4

Sequence Number

16 12

Payload (Ethernet/802.3 PDU)

Set to 0 to signify PW data

39

ATM Cell Mode Encapsulation for Transport over MPLS

  2 modes relevant to backhaul: –  One-to-One Cell Mode - maps

one ATM VCC (or VPC) to one PW –  N-to-One Cell Mode - maps one or

more ATM VCCs (or VPCs) to one PW (shown above); only required mode for ATM support

  Ingress performs no reassembly   Control word is optional: If used, Flag and Length bits are not used

Tunnel Header

PW Header

4 octets 4 octets Control word

ATM cell #1 minus FCS

4 octets 52 octets ATM cell #2 minus FCS

52 octets

…

0000 Flags Res

bits 4 4 4

Length

6

Sequence Number

16

Control Word N-to-One Cell Mode Multiple Cell Encapsulation

Control Word (optional)

PTI C VCI VPI

PTI C VCI VPI

ATM Payload (48 bytes) “ “

ATM Payload (48 bytes) “ “

RFC 4717

40

  Structure agnostic transport for TDM (T1, E1, T3 and E3) bit streams –  Ignores structure imposed by standard TDM framing –  Used in applications where PEs do not need to interpret TDM data or

participate in TDM signaling   SAToP Control Word allows:

–  Detection of packet loss or mis-ordering –  Differentiation between MPLS and AC problems as causes for emulated

service outages –  Conservation of MPLS network bandwidth by not transferring invalid data

(AIS) –  Signaling of faults detected at PW egress to the PW ingress

SAToP Control Word

RFC 4553

Structure-Agnostic TDM Encapsulation for Transport over MPLS (SAToP)

Tunnel Header

PW Header

4 octets 4 octets Control Word Fixed RTP Header*

4 octets

0000 L R RSV

bits 4 1 2

Length

6

Sequence Number

16 1 * Optional see RFC 3550 2

FRG

TDM Payload

41

PW Control Plane

MPLS PE PE

Layer 2 AC

Layer 2 AC

CE CE

Payload (L2 protocol)

Tunnel LSP

LSP Label Outer Label

MPLS Label Stack

Pseudowire

PW Label Inner Label Ethernet

ATM TDM, etc

PW Setup and Maintenance: IETF RFC 4447

RSVP-TE or LDP

Targeted LDP

PWs have a control plane that signals binding of PW label to the PW FEC

42

MPLS Pseudowires for Backhaul

  Pseudowires –  Emulate a native layer 2 service, such as Ethernet, TDM, ATM VC/VP,

FR VC, etc   Many PWs carried across MPLS network in a tunnel LSP

–  PWs can utilise features of the MPLS network for resiliency, QoS, etc

T-LSP Label Outer Label

MPLS Label Stack

Pseudowire

Cell-site PE

MTSO PE

L2 AC

L2 AC

PW frame payload

(L2 protocol)

Tunnel LSP

PW Label Inner Label

BTS

2G

eNB, BS 4G

Node B

3G

MPLS RAN

43

Multi-Segment PW for Backhaul

A static or dynamically configured set of two or more contiguous PW segments that behave and function as a single point-to-point PW

Enables:   Scalability – to hundreds of base stations connecting to RNC/BSC site   Multi-domain operation – including multi-provider backhaul networks   Multi-technology operation – leverage mechanisms from non-MPLS access

infrastructures

Pseudowires

S-PE T-PE Tunnel LSP

MPLS Aggregation MPLS Access

Hub

Cell Site

MTSO

T-PE

Ethernet, TDM, ATM MS-PW

BTS

2G

eNB, BS 4G

Node B

3G

MPLS OAM and Protection

Operations, Administration and Management (OAM) capabilities of IP/MPLS mobile backhaul networks

45

MPLS for Backhaul: OAM Requirements

  OAM needed for reactive & proactive network maintenance –  Quick detection and localization of a defect –  Proactive connectivity verification and performance

monitoring   OAM tools have a cost and revenue impact to

carriers –  Reduce troubleshooting time and therefore reduce

OPEX –  Enable delivery of high-margin premium services

which require a short restoration time   Top level requirements

–  Provide/co-ordinate OAM at relevant levels in IP/MPLS network

–  Proactive and reactive mechanisms, independent at all levels

Service Level e.g ATM OAM, MAC-Ping

VLL / PW Level e.g VCCV, PW status

Tunnel LSP Level e.g LSP ping

46

Operator GUI

OSS

OAM Notification

(flat file)

OAM Notification

OAM and Service Assurance: Mobile Backhaul

Calculate SLA Performance Metrics

Test Service Latency, Jitter, Packet Loss and Round-trip Delay

Monitor Alerts for Potential SLA Violation

Schedule a Suite of Tests at Service Activation or Time of Day

Automate On-Demand Test Suites from Fault Notification

Pseudowires

Cell-site PE

MTSO PE

L2 AC L2 AC

Tunnel LSP

MPLS RAN BTS

2G

eNB, BS 4G

Node B

3G

47

Service-Aware OAM Toolkit

Tool set for reactive & proactive network operation and maintenance   Defect detection, proactive connectivity verification, and performance monitoring   Provide/co-ordinate OAM at relevant levels in IP/MPLS network

– Services Level: Eth CFM, Eth EFM, ATM, FR loopback, SAA – Tunnel LSP Level: LSP ping and LSP Traceroute – Pseudowire Level: PW Status, VCCV-BFD, VCCV-Ping, mapping to Ethernet, TDM, ATM

notifications

  MPLS is currently being extended to provide additional packet transport capabilities (MPLS-TP) for performance monitoring, path segment monitoring and alarm suppression

Quickly isolate and troubleshoot faults to reduce MTTR

BTS 2G

eNB, BS 4G

Node B 3G Pseudowires

Tunnel LSP


Hub

Cell Site

MTSO

VLL / PW Level e.g BFD, VCCV, PW status

Service Level e.g ATM OAM, SDP-Ping

Tunnel / LSP Level e.g LSP Ping & Traceroute

48

LSP Ping

  LSP Ping is MPLS specific variation of traditional ICMP ping/traceroute ad hoc tool

–  Ping is simple e2e loopback –  Traceroute uses TTL to incrementally verify path

  Ping paradigm useful for craftsperson initiated testing –  TELNET/CLI

  LSP Ping is augmented with a number of TLVs processed by the receiver to extend functionality

  As LSP is unidirectional, and Ping is bi-directional, LSP Ping is augmented with options for distinguishing real problems from return path problems

49

Bidirectional Forwarding Detection (BFD)

  Simple, fixed-field, hello protocol –  Easily implemented in hardware –  Very useful as a fault-detection mechanism

  Nodes transmit BFD packets periodically over respective directions of a path

  If a node stops receiving BFD packets some component of the bidirectional path is assumed to have failed

  Applicable to tunnel end-points

50

Virtual Circuit Connection Verification (VCCV)

 Mechanism for connectivity verification of PW  Multiple PSN tunnel types

– MPLS, IPSec, L2TP, GRE,…  Motivation

– One tunnel can serve many pseudo-wires – MPLS LSP ping is sufficient to monitor the PSN tunnel (PE-PE

connectivity), but not PWs inside of tunnel  Features

– Works over MPLS or IP networks –  In-band CV via control word flag or out-of-band option by inserting router

alert label between tunnel and PW labels – Works with BFD, ICMP Ping and/or LSP ping

PE2 PE1

Attachment Circuit

Attachment Circuit

PSN

Pseudowire

4G-3G-2G A GW/

HBSC/RNC Complex

BTS 2G

eNB, BS 4G

Node B 3G

51

PW Status Signaling

PWs have OAM capabilities to signal defect notifications:   Defect status mapped between AC and PW in the PE   PW status signaling propagates defect notifications along PW

- Extension to T-LDP signaling

PE2 PE1

Attachment Circuit

Attachment Circuit

PSN

Pseudowire

AC defect PW status: AC RX fault AC defect

4G-3G-2G A GW/

HBSC/RNC Complex

BTS 2G

eNB, BS 4G

Node B 3G

52

PW Status Signaling: Multi-segment PWs

  PW status signaling also works for MS-PWs   S-PEs:

–  Transparently pass remote defect notifications –  Generate notifications of local defects

Pseudowires

S-PE T-PE Tunnel LSP


Hub

Cell Site

MTSO

T-PE

PW Status BTS

2G

eNB, BS 4G

Node B

3G

53

Network Level Recovery  Dual-homing w/o RSTP  MPLS FRR  MPLS Standby Secondary  Sub 50 ms restoration  End-to-end path protection  MPLS extensions to include

additional approaches

MPLS Network Reliability

Both node level and network level recovery are required

A GW/ RNC

MPLS RAN

Ethernet

ATM (IMA)

active

standby

Node Level Recovery  Non-stop routing for ALL protocols (LDP,

OSPF, IS-IS, BGP, multicast, PIM-SM)  Non-Stop Service for ALL services (VPLS,

VLL, IP-VPN, IES, multicast)

eNB, BS 4G

Node B

3G

54

Network Level Redundancy for PWs

Protects against PE and AC failures   PE configured with multiple pseudowires per service with multiple end-

points   Local precedence indicates primary PW for forwarding if multiple PWs are

operationally UP   PW status exchanged end-to-end to notify PEs of operational state of both

PWs & ports / attachment circuits (PW Status Notification).

draft-ietf-pwe3-pw-redundancy & draft-ietf-pwe3-redundancy-bit

A GW/ RNC

MPLS RAN

AC redundancy: MC – APS MC - LAG

active

standby

AC redundancy protocol drives forwarding state of PWs/PEs

Forwarding direction determined by PW state

PW status

Active/standby state of LAG/APS sub-groups reflected in PW status

Ethernet

ATM (IMA)

eNB, BS 4G

Node B

3G

Packet Synchronization and Timing

56

The Need for Synchronization in Mobile Networks

  Synchronization is vital across many elements in the mobile network

  In the Radio Access Network (RAN), the need is focused in three principal areas

NodeB

NobeB

eNB or BS

eNB or BS

RNC

A GW

RNC

1: Radio Framing Accuracy

2 : Handoff Control 3 : Backhaul

Transport Reliability

Mobile Core Network(s)

57

Radio Framing Accuracy

  In Time Division Duplexing (TDD), the base station clocks must be time synchronized to ensure no overlap of their transmissions within the TDD frames

–  Ensuring synchronization allows for tighter accuracies and reduced guard-bands to ensure high bandwidth utilization

  In Frequency Division Duplexing (FDD) centre frequencies must be accurate for receivers to lock

58

Handoff Control For Reliable Mobility Performance

  Synchronization is vital to ensure service continuity (i.e successful handoff)

  Studies have shown significant reduction in call drops when good synchronization is in place; enhanced QoE

59

Backhaul Transport Reliability

  Wander and Jitter in the Backhaul and Aggregation Network can cause underflows and overflows

  Slips in the PDH framing will cause bit errors leading to packet rejections

  Packet rejections lead to retransmissions and major perceptible slow down in TCP windowed sessions

A GW/ RNC/ BSC

eNB/BS/ NodeB/BTS X

TCP end-to-end windowed transmission

Backhaul network

60

Clock distribution methods

  Physical layer clock –  Using synchronous TDM interfaces, e.g. PDH/SDH –  Using synchronous Ethernet as per G.8261/G.8262, and G.

8264 for ESMC/SSM –  External Timing Interface

  GPS synchronization   Clock distribution over packet network

–  IEEE 1588-2008 – ITU-T Q13/SG15 currently developing an IEEE Std 1588-2008 "telecom profile" for frequency distribution

–  NTP – The IETF is currently developing NTPv4*   Adaptive & Differential Clock Synchronization   Multiple methods might be deployed in a network

*Note: NTPv3 requires equipment with high quality oscillators

MPLS Mobile Backhaul Initiative – MMBI

62

MMBI Scope

  MPLS technology to transport mobile traffic (user plane and control plane) over access, aggregation and core networks

  4G (LTE), 3G, 2.5G and 2G networks, including evolution   RAN and Core equipments with range of physical interfaces (e.g.

FE, GE, E1/T1, STM1/OC-3, DSL, etc.) and technologies (PDH, SDH/SONET, ATM and ATM/IMA, PPP, FR, Ethernet, etc.), either directly attached or through an intervening access network

  Different kinds of access transmission technologies: pt-to-pt access (xDSL, microwave, P2P Fiber), pt-to-mp access (GPON)

  Address coexistence of legacy and next generation mobile equipment in the same network infrastructure.

  Support a smooth migration strategy for network operators as newer TNLs (Transport Network Layers) are introduced and legacy TNLs are phased out

63

  MPLS facilities in Access and/or Aggregation networks leased from a third party, and which may be shared by more than one mobile operator

  Converged access/aggregation network supporting both wireline, e.g. residential and enterprise, and wireless services.

  QoS for support of distinct service types (e.g. real-time services and associated delay and jitter requirements)

  Support for clock distribution to the base stations, including frequency, phase and time synchronization

  Resiliency capabilities, including failover times appropriate for wireless backhaul networks. E.g. dual attachment at the BSC/RNC and methods for failover.

  OAM mechanisms

MMBI Scope (continued)

64

Multiple TNLs – Successive Generations of Mobile Architecture

Network Specification Transport Network Layer (TNL)

GSM/GPRS/EDGE (2G/2.5G)

TDM, IP*

UMTS R3, R99/R4 ATM

R99/R5, R6, R7 ATM

IP CDMA 1x-RTT IS-2000 HDLC or TDM

CDMA 1x EV-DO IS-856 IP

LTE R9, R10 IP

*Note: some 2G and 2.5G equipment can be upgraded to use an IP TNL

65

MMBI Architecture and Use Cases

  Deployment Scenarios -- Location for MPLS functions is intended to be flexible –  MPLS interworking functions could be located either:

  In the edge node, or   in the access node, or   in the access gateway or   directly integrated into the base station.

  TNL (Transport Network Layer) Scenarios – Support for a range of access technologies at base stations and controller elements –  Case 1: TDM TNL

  Base stations and controller elements communicating using TDM bit streams

–  Case 2: ATM TNL   Base stations and controller elements communicating using ATM cells

–  Case 3: IP TNL   Base stations and controller communicating using IP packets

–  Case 4: HDLC TNL   Base stations and controller elements communicating using HDLC-

encoded bit streams (e.g. CDMA)

66

Typical 2G and 3G RAN Topology

  Star topology enabling communication from BS to Controller and from Controller to BS

  Centralized topology

67

Typical LTE RAN Topology

  Star topology enabling communication from BS to aGW and communication from aGW to BS.

  Neighboring any-to-any topology enabling communication between BSs

  Flat topology

68

MMBI Reference Architecture – 2G/3G

69

Generic TNL Protocol Stack – 2G/3G Architecture: Example of SS-PW Deployment

Access Node

TDM ATM

Ethernet

TDM ATM

Ethernet

MPLS network

Access network

MASG CSG RC BS

MPLS Node

PE P PE

MPLS Node

P Aggregation network TNL PW

  PW extends from PE to PE –  Each TNL Type supported by corresponding TNL PW –  In deployment scenario shown, PW extends from Cell Site Gateway

(CSG) to Mobile Aggregation Site Gateway (MASG)

TNL PW

L1 L1

L1

LSP

L1

TNL PW TNL

LSP

L1

TNL PW

L2 LSP

L1

TNL

L1

LSP L2 L2

L1 L1

L2

L1

TNL TNL

L2

L1

LSP L2 L2

L1

LSP LSP

70

Generic TNL Protocol Stack – 2G/3G Architecture: Example of MS-PW Deployment

Access Node

TDM ATM

Ethernet TDM ATM

Ethernet

MPLS network

Access network

MASG CSG

RC BS

MPLS

T - PE T - PE S - PE Aggregation network TNL PW

  PW extends from T-PE to T-PE; switched at S-PE –  Each TNL Type supported by corresponding TNL PW –  In deployment scenario shown, PW extends from Cell Site Gateway

(CSG) to Mobile Aggregation Site Gateway (MASG)

TNL PW

L1 L1

L1

LSP

L1

TNL PW TNL

LSP LSP

L1

TNL PW

L2

LSP

L1

TNL

L1

LSP

L2 L2

L1 L1

L2

L1

TNL TNL

L2

TNL PW TNL PW LSP

71

MMBI: Timing deployment scenarios

PHY clock

BNG TNL TNL

Aggregation network

Access Aggregation

Access network xDSL, microwave, Leased Line, GPON, Optical Eth

Access Node Access

Gateway Edge Node

A Core

mobile network

2 G - 3 G BS C / RNC

Complex

Iu - CS Iu - PS Gb

Iu - PS

Iu-CS A

SGSN 3G SGSN 2G

/ MPLS MSC 3G

PRC via

GPS ( a 1 )

( b )

( c )

( d )

Gb

( a 2 ) ( a 3 )

BTS / Node B

BTS / Node B CSG BTS / Node B MASG

( a 4 )

MSC 2G

PKT clock

72

IP transformation in mobile networks with evolution to LTE

RNC

Radio intelligence moving to

eNodeB

1 2 4

Node B

Multimedia Services

SGSN

Backhaul (TDM/ATM)

RNC bearer mobility evolves to the SGW

3

Backhaul transition

to IP/Ethernet

Backhaul (IP/Ethernet)

MCS voice and SGSN packet

mobility evolves into the SGW

RNC control distributed into

the MME/eNB

SGSN control evolves into

the MME

CS Core

5

CS and PS evolve into a unified all-IP

domain

Service and mobile aware all-IP network

MME PCRF

PDN GW SGW eNB

PS Core

GGSN

Best effort to

e2e QoS

6 7

Internet

TODAY

LTE

73

LTE Evolved Packet System (EPS) Backhaul (IP TNL Application)

The Evolved Packet System consists of the following sub-systems: •  User Equipment (UE) which includes specialized security cards often identified as part of the

EUTRAN (detail not shown) •  Evolved UTRAN (EUTRAN) which consists of the evolved Node B (eNB) •  Evolved Packet Core (EPC) which includes the following nodes:

−  Serving Gateway (S-GW) which serves as a mobility anchor for inter-eNB handover −  PDN Gateway (P-GW) which is the cross-technology mobility anchor in the EPS −  The Mobility Management Entity (MME) which handles authentication and signaling for

connection and mobility management −  The Policy and Charging Rules Function (PCRF) supports per session QoS and associated billing

•  Applications include IMS as well as non-IMS −  UEs signal directly to the applications

HSS: Home Subscriber Server

MME

HSS

S-GW

S6a

P-GW

S11 S5/S8

eNB SGi

S1-MME

S1-U PDN

PCRF

Gx

eNB

X2

IMS Apps

Rx

S10

S5

EUTRAN EPC Applications UE

74

Policy, Charging & Rules Function   Network control of Service Data Flow (SDF)

detection, gating, QoS & flow based charging   Dynamic policy decision on service data flow

treatment in the PCEF (xGW)   Authorizes QoS resources

Evolved Packet Core: Overview of components and functionality

 eNodeB:  all radio access functions

  Radio admission control

  Scheduling of UL and DL data

  Scheduling and transmission of paging and system broadcast

  IP header compression (PDCP)

  Outer-ARQ (RLC)

Mobility Management Entity   Authentication   Tracking area list management   Idle mode UE reachability   S-GW/PDN-GW selection   Inter core network node signaling for

mobility between 2G/3G and LTE   Bearer management functions

PDN Gateway   IP anchor point for bearers   UE IP address allocation   Per-user based packet filtering   Connectivity to packet data network

Policy

PCRF

Decisions

Serving Gateway   Local mobility anchor for inter-eNB handovers   Mobility anchoring for inter-3GPP handovers   Idle mode DL packet buffering   Lawful interception   Packet routing and forwarding

75

MMBI Reference Architecture - LTE

  Flat Topology RANs using IP TNL:

  MPLS provides two solutions that can be applied to combination of any-to-any and star topologies: –  Layer 2 VPNs e.g. VPLS –  Layer 3 VPNs e.g. BGP IP/VPNs RFC 4364

Network Specification TNL

HSPA+ flat 3GPP R7 IP LTE 3GPP R8

76

MMBI Reference Architecture – VPLS Use Cases

IP TNL


(MASG)

IP TNL IP TNL

Aggregation network

BS1

Access Aggregation

Access network Access

Node

Cell SIte Gateway

(CSG)

Edge Node IP/MPLS

Core network

Core

aGW

S3/S4

L2VPN MPLS transport network solutions

VSI Eth PW

Edge Node

Edge Node

S5/S8a S1

S1

S1

VPLS VPLS

VPLS Full mesh

H - VPLS Spoke PWs

CSG1 CSG2 CSG3 CSG1 CSG2 CSG3 CSG1 CSG2 CSG3

IP TNL S1

CSG1

CSG2

CSG3

CSG1 CSG2 CSG3

Access network

BS2

BS3

Ethernet Ethernet

aGW

S3/S4 SGSN S5/S8a

PDN GW

HSS S6a

S6a

Note: BS supports Ethernet interface. One Cell Site Gateway can connect multiple BS.

MPLS PE function could be integrated into the aGW (MME GW, S - GW, ASN GW)

VPLS

H-VPLS

77

MMBI Reference Architecture – L3VPN Use Cases

IP TNL

Note: BS supports Ethernet interface. One Cell Site Gateway can connect multiple BS.


(MASG)

IP TNL IP TNL

Aggregation network

BS1

Access Aggregation

Access network Access

Node

Cell SIte Gateway

(CSG)

Edge Node IP/MPLS

Core network

Core

aGW

S3/S4

L3VPN MPLS transport network solutions

VRF

S3/S4 SGSN Edge Node

Edge Node

S5/S8a S1

S1 S5/S8a

PDN GW

HSS S6a S1

L3VPN L3VPN

L3VPN

CSG1 CSG2 CSG3 CSG1 CSG2 CSG3 CSG1 CSG2 CSG3

IP TNL S1

CSG1

CSG2

CSG3 Access network

BS2

BS3

IP IP

aGW MPLS PE function could be integrated into the aGW (MME GW, S - GW, ASN GW)

S6a

L3VPN MPLS

78

Abstract Test Suite for TDMoMPLS

  TDMoMPLS –  46 Test Cases

  Additional 11 Synchronization Test Cases

  The Abstract Test Suite for TDM Services over MPLS describes test procedures based on the requirements for encapsulating TDM signals over MPLS networks and distributing timing using pseudo-wires over a MPLS network. Test cases in this specification are defined for T1, E1, T3 and E3 services.

–  An overview of the different groups of requirements that compose the TDM circuit emulation   Services over MPLS is provided as follows:   Packet format and encapsulation layer   Usage of optional RTP header   Structure-agnostic emulation   Structure-aware emulation   Packetization and depacketization   TDMoMPLS defects   Performance monitoring   Synchronization distribution and performance (Normative Annex)

79

Abstract Test Suite for ATMoMPLS

  ATMoMPLS –  Draft –  Currently 50 Test Cases

  The Abstract Test Suite for ATM over MPLS describes test procedures based on requirements for encapsulating Asynchronous Transfer Mode (ATM) over MPLS networks. –  An overview of the different groups of requirements that

compose the Abstract Test Suite for ATMoMPLS is provided as follows:  Packet format and encapsulation  OAM - Fault & Performance management  QOS Mapping  Synchronization (ref: ATS for TDMoMPLS Annex S)

80

Future Certification Test Suite Development

 Ethernet over MPLS  IP over MPLS

81

Certification Benefits

  Service Provider community –  Vendor meets requirements –  Potential savings of resources

  Vendor community –  Marketing tool –  Shortening test cycle –  Carefully written test cases, better specifications

  User community –  Purchase equipment with confidence


Summary of Success Factors

83

  Backhaul transformation is essential for 2G/3G (scalability and cost reduction) and evolution to a LTE all IP flat architecture

  Co-existence of multiple transport options (ATM, TDM, Ethernet) for investment protection

  Carrier Grade IP/MPLS services –  High Availability –  Fast reconvergence

  Efficient End-to-End Management and OAM for rapid mass deployment

  Scalability to large numbers of cell sites   Base Station synchronization

–  Carrier frequency accuracy of 50 PPB for LTE, WiMAX, GSM/W, CDMA

–  Need to preserve synchronization & timing with Carrier Ethernet transport

MPLS in Mobile Backhaul: Critical Success Factors

84

Focus from the Broadband Forum   Rapid growth in mobile backhaul bandwidth demand

–  Scaling the backhaul in TDM way for all traffic is expensive –  Industry is shifting towards IP based networks

  Can migrate entire mobile RAN OR   Hybrid model - Use MPLS for the data traffic and voice remains on

TDM

  IP/MPLS offers many benefits and has been deployed globally in mobile core. Similar drivers apply to backhaul.

  Standards for backhaul transport - leaning towards IP   In recent years, the Broadband Forum has published

implementation agreements to facilitate the migration of ATM and TDM to MPLS-based infrastructure

  Broadband Forum aims to complement the cost benefits of Ethernet with the proven track record of MPLS for building converged, reliable and QoS-aware mobile grade infrastructure.

85

  Technical Specifications for MPLS Based Mobile Backhaul Networks for LTE (WT-221)

  Technical Specifications for MPLS Based Mobile Backhaul Networks for 2G & 3G (WT-222)

  Equipment Requirements for MPLS over Aggregated Interfaces – e.g., MPLS over Ethernet LAG (WT-223)

  MPLS in Carrier Ethernet Networks – network architecture for providing carrier Ethernet services (WT-224)

  Abstract Test Suite for ATM over MPLS – Certification testing (WT-225)

Broadband Forum Mobile Backhaul work in progress

86

  3GPP: http://www.3gpp.org

  Broadband Forum: http://www.broadband-forum.org

  IEEE: http://www.ieee.org

  IETF: http://www.ietf.org

  ITU-T SG 15: http://www.itu.int/ITU-T/studygroups/com15/index.asp

  Metro Ethernet Forum (MEF): http://metroethernetforum.org

  Next Generation Mobile Network Initiative (NGMN): http://www.ngmn.org

  WiMAX Forum: http://www.wimaxforum.org

Related Standards Organizations and Consortiums

For more information, visit us at http://

www.broadband-forum.org

Thank you for attending the MPLS in Mobile Backhaul Tutorial

The Broadband Forum is a non-profit corporation organized to create guidelines for broadband network system development and deployment. This Broadband Forum educational presentation has been approved by members of the Forum. This Broadband Forum educational presentation is not binding on the Broadband Forum, any of its members, or any developer or service provider. This Broadband Forum educational presentation is subject to change, but only with approval of members of the Forum. This educational presentation is copyrighted by the Broadband Forum, and all rights are reserved. Portions of this educational presentation may be copyrighted by Broadband Forum members or external sources.

88

Abbreviations

MGW – Message gateway MMBI – MPLS in mobile backhaul initiative MME – Mobility management entity MPLS – Multiprotocol label switching MPLS-TP – MPLS Transport Profile MSC – Mobile switching center MTSO – Mobile telephone switching office Node B – Base station transceiver with UMTS/WCDMA PCRF – Policy and charging function PDN – Packet data network PDSN – Packet data serving node P-GW – PDN gateway PS – Packet switched PW – Pseudowire RAN – Radio access network RNC – Radio network controller RSVP – Resource reservation protocol SGSN – Serving GPRS support node S-GW – Serving gateway TE – Traffic engineering TNL – Transport network layer UE – User equipment UMB – Ultra mobile broadband UMTS – Universal mobile telecommunications system VLAN – Virtual local area network VPN – Virtual private network WAC – WiMAX wireless access controller WiMAX – Worldwide interoperability for microwave access

2G – Second generation mobile network 3G – Third generation mobile network 4G – Fourth generation mobile network AG – Access gateway aGW– Access gateway ASN – Access service node BS – Base station BSC – Base station controller BTS – Base transceiver station CDMA – Code division multiple access CS – Circuit switched CSG – Cell site gateway EDGE – Enhance data rates for GSM evolution eNB - – 4G/LTE base station eNode B – 4G/LTE base station EPC – Evolved packet core EUTRAN – Evolved UTRAN EV-DO – Evolution data optimized FEC – Forwarding equivalence class FRR – Fast re-route GGSN – Gateway GPRS support node GPRS – General packet radio service GSM – Global system for mobile communications GW – Gateway HSPA – High speed packet access HSS – Home subscriber server LSP – Label switched path LTE – Long term evolution MASG – Mobile aggregation site gateway

Documents

MPLS in Mobile Backhaul