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  • 1. MPLS in Mobile Backhaul MR-234 Luyuan Fang Issue 2 Broadband Forum Ambassador May 2010 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 2
  • 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 3
  • 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. 4
  • 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 5 broadband-forum.org
  • 6. Broadband Forum Scope PARTNER APPLICATION Management Quality of Experience IDENTITY TR-069 (CWMP) TR-069 ACS FUNCTION Identity, Accounting and Policy Operations and Network Management DSL Quality Management BILLING PARTNER CONTROL TR-126 IPTV TR-176 DSL OSS FUNCTION Quality of Experience Profiles for IPTV CWMP TR-069 Network TR-144 Multi Service Requirements Multi-Service Core Edge Aggregation Access VoD SIP TV Content Network P2P E-FTTx TR-101, TR-156 GPON IP/MPLS Ethernet EPON Aggregation DSL Mobile Network SGW RNC BSC Multi Service Architecture & Requirements Certification, Test and Interoperability 6 broadband-forum.org
  • 7. We don’t work alone Coordinated industry efforts maximize value with minimum overlap 7 broadband-forum.org
  • 8. MPLS in Mobile Backhaul 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 Declining average –  Reduction or flattening of growth in revenue per user minutes per subscriber in markets (ARPU) 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 9
  • 10. Evolution to LTE is all about services 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 CDMA CDMA2000 CDMA2000 EV-DO EV-DO LTE 1X 1xEV-DO Rev A Rev B DL: 153 kbps DL: 2.4 Mbps DL: 3.1 Mbps DL: 3.1-73 Mbps Requirement: UL: 153 kbps UL: 153 kbps UL: 1.8 Mbps UL: 1.8-27 Mbps DL: 100 Mbps Services Real-time UL: 50 Mbps Broadband data apps Voice VOD, MOD Video Multimedia, High-speed data Broadband Picture/Video High-speed telephony, VoIP, Video Delivery, Real-time VoIP,PTx, Email Internet Applications Advanced IMS Web browsing Enterprise Interactive applications gaming, Multimedia WCDMA GSM UMTS (W-CDMA) HSPA+ HSPA+ HSDPA HSUPA EDGE Rel 7 Rel 8 LTE GPRS R99 Rel 5 Rel 6 Phase 2 Phase 1 DL: 114 kbps DL: 384 kbps DL: 384 kbps DL: 1.8-7.2 Mbps DL: 7.2 Mbps Target: Requirement: UL: 114 kbps UL: 384 kbps UL: 384 kbps UL: 384Kbps UL: 5.2 Mbps DL: 40 Mbps DL: 100 Mbps UL: 10 Mbps UL: 50 Mbps TRANSPORT TDM (SONET/SDH, PDH) FR, HDLC, ATM/IMA IP/Ethernet 10
  • 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 11
  • 12. From 2G/3G to LTE: Towards all-IP, simplified network architecture 2G/3G Broadband Forum focus areas for backhaul Softswitch GMSC MGW PSTN CDMA / EVDO Circuit Switched Core (Voice) Other GSM / GPRS Voice MSC mobile networks EDGE Channels BTS IP channel BSC / RNC UMTS Internet Node B Packet Switched HSPA Core VPN SGSN GGSN PDSN HA New, all-IP mobile core network introduced with LTE What is EPC ?   End-to-end IP   Clear delineation of control plane and data plane LTE+EPC   Simplified architecture: flat-IP architecture with a single core IP channel Evolved Packet Core eNode B (eNB) (All-IP) Transport (backhaul and backbone) Evolved Packet Core = end-to-end IP transformation of mobile core 12
  • 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 13
  • 14. Backhaul connections Growth (By Technology Type) Worldwide Mobile Backhaul New Connectivity by Technology   Operators migrating mobile backhaul to converged, packet- based architectures   Microwave used extensively in Europe and Asia   Multiple options for backhaul transport   Varies based on geography, availability, volume, inter/ intra carrier relationships Source: Infonetics, 2008 14
  • 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 15
  • 16. LTE Deployment requires evolution of backhaul transport LTE+EPC eNB IP channel Evolved Packet Core (All-IP) eNB Transport (backhaul and backbone)   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 16
  • 17. LTE Deployment requires evolution of backhaul transport (continued) LTE+EPC eNB IP channel Evolved Packet Core (All-IP) eNB Transport (backhaul and backbone)   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) 17
  • 18. Why MPLS?  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 18
  • 19. Why IP/MPLS in Mobile Backhaul?   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) IP/MPLS Scalability Resiliency Multi-Service Manageability TE/QOS 19
  • 20. Multi-phase MPLS migration into RAN Transport Phase 1 Radio Access Network IP/MPLS Backbone Cell Site Hub MTSO TDM Enet/PPP T1/E1 T1/E1 Enet Copper Copper Fiber BSC RNC WAC TDM/IP ATM/IP Enet ATM PPP TDM ATM PPP Enet Converged T1/E1 T1/E1 Aggregation SDH/SONET Copper Copper via Fiber IP/MPLS 2G – TDM/IP 3G – ATM/IP SDH/SONET Backbone WiMAX - Enet TDM ATM PPP Enet TDM ATM PPP Enet LTE - Enet µwave (PDH channels) µwave (SDH ch) Separate transmission facilities for different ATM Central Aggregation, Aggregation Consolidation, technologies Overlay Service Routing MPLS “edge” 20
  • 21. Multi-phase MPLS migration into RAN Transport Phase 2 Radio Access Network IP/MPLS Backbone Cell Site Hub TDM ATM PPP Enet MTSO MPLS SDH/SONET TDM Enet/PPP MPLS fiber T1/E1 T1/E1 Aggregation BSC RNC WAC Copper Copper TDM ATM PPP Enet for all MPLS TDM/IP ATM/IP Enet ATM PPP Technologies Ethernet Converged T1/E1 T1/E1 Copper Copper fiber IP/MPLS 2G – TDM/IP 3G – ATM/IP Backbone WiMAX - Enet TDM ATM PPP Enet TDM ATM PPP Enet LTE - Enet µwave (PDH channels) MPLS Ethernet ch Separate transmission µwave facilities for different Central Aggregation, Common facility for Consolidation, technologies all traffic Service Routing MPLS “edge” 21
  • 22. Multi-phase MPLS migration into RAN Transport Phase 3 Radio Access Network IP/MPLS Backbone Cell Site TDM ATM Enet IP Hub TDM ATM Enet MTSO MPLS MPLS SDH/SONET SDH/SONET MPLS fiber MPLS fiber Aggregation Aggregation BSC RNC WAC TDM ATM Enet IP TDM ATM Enet for all for all MPLS MPLS TDM/IP ATM/IP Enet Technologies Ethernet Technologies Ethernet Converged fiber fiber IP/MPLS 2G – TDM/IP Backbone 3G – ATM/IP WiMAX - Enet TDM ATM Enet IP TDM ATM Enet LTE - Enet MPLS MPLS Ethernet ch Ethernet ch µwave µwave Router Common facility for Common facility for all traffic all traffic MPLS “edge” IP/MPLS is agnostic to transmission techniques in Access 22
  • 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 23
  • 24. 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) 24
  • 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 25
  • 26. MMBI Reference Architecture (more on this later) Access Aggregation Core BS Cell Site Gateway Mobile Aggregation Abis Site Gateway TDM TNL MSC 2G Edge RC A A Access Node TDM TNL Abis Gb MSC 3G Iub Access network Iu-CS ATM TNL xDSL, Node Edge S5/S8A Node ATM TNL Iub IP/ microwave, Aggregation MPLS S5/S8A Leased network Core PDN GW Iub/S1 Line, Edge IP Iub/S1 mobile IP TNL GPON, Node Edge TNL networ Gb Optical Eth Node HDLC Abis Iu-CS k TNL Iu-PS SGSN 2G Abis Iu-PS HDLC TNL MPLS transport network Iur SGSN 3G MPLS PE function could be integrated into RAN the BS (BTS/Node B/BS)/RC Terminology WCDMA/ CDMA LTE Technology Data Services UMTS 2000/1x GSM/UMTS EDGE, GPRS, HSPA Base Station Node-B BTS eNB CDMA CDMA2000, 1xRTT, Base Station Controller RNC BSC A GW EV-DO Circuit Edge devices MSC MSC - Packet Edge devices SGSN, GGSN PDSN PDN GW 4G LTE 26
  • 27. 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) 28
  • 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 IP destination network 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 29
  • 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 30
  • 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 31
  • 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 32 –  RFC 4090: FRR extensions to RSVP
  • 33. 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. 34
  • 35. MPLS Pseudowire Reference Model Native Emulated Service Pseudowire (PW) (forward) MPLS Tunnel LSP (forward) AC AC CE1 PE1 IP/MPLS Network PE2 CE2 MPLS Tunnel LSP (backward) Pseudowire (backward) AC: Attachment Circuit ATM, Ethernet , FR, IP, TDM, etc Attachment CE: Customer Edge Circuit (AC) PE: Provider Edge - Same at each end 35
  • 36. MPLS Point-to-Point Services Label Stacking Tunnel PW VC Encaps Header Layer 2 payload Header Information 1 2 3   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 36
  • 37. Layer 2 Encapsulation - PWE3   Ethernet 3G to 4G (LTE/WiMax)  RFC 4448   ATM cell and ATM AAL5 3G R99/R3 UMTS  RFC 4717   TDM 2G to 3G  RFC 4553 (structure agnostic)  RFC 5086 (CES0PSN)   PPP/HDLC CDMA  RFC 4618 37
  • 38. Encapsulation Methods for Transport of Ethernet over MPLS Networks 4 octets 4 octets 4 octets Tunnel PW Control Header Header Word Payload (Ethernet/802.3 PDU) bits 4 12 16 Set to 0 to 0000 Reserved Sequence Number signify PW data Control Word (use is optional)   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 RFC 4448 38
  • 39. ATM Cell Mode Encapsulation for Transport over MPLS 4 octets 4 octets 4 octets 52 octets 52 octets Tunnel PW Control ATM cell #1 ATM cell #2 Header Header word minus FCS minus FCS … bits 4 4 4 6 16 0000 Flags Res Length Sequence Number Control Word N-to-One Cell Mode Multiple Cell Encapsulation   2 modes relevant to backhaul: Control Word (optional) –  One-to-One Cell Mode - maps VPI VCI PTI C one ATM VCC (or VPC) to one PW ATM Payload (48 bytes) –  N-to-One Cell Mode - maps one or “ “ more ATM VCCs (or VPCs) to one VPI VCI PTI C PW (shown above); only required ATM Payload (48 bytes) mode for ATM support “ “   Ingress performs no reassembly   Control word is optional: If used, Flag and Length bits are not used 39 RFC 4717
  • 40. Structure-Agnostic TDM Encapsulation for Transport over MPLS (SAToP) 4 octets 4 octets 4 octets Tunnel PW Control Header Header Word Fixed RTP Header* TDM Payload 2 2 * Optional see RFC 3550 bits 4 1 1 6 16 0000 L R RSV FRG Length Sequence Number SAToP Control Word   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 40 RFC 4553
  • 41. PW Control Plane PWs have a control plane that signals binding of PW label to the PW FEC PE MPLS PE Tunnel LSP Layer 2 Pseudowire Layer 2 AC AC CE CE Payload (L2 protocol) Ethernet Targeted LDP ATM PW Label Inner Label TDM, etc LSP Label Outer Label RSVP-TE or LDP MPLS Label Stack PW Setup and Maintenance: IETF RFC 4447 41
  • 42. MPLS Pseudowires for Backhaul 2G BTS L2 AC MPLS RAN MTSO PE L2 AC 3G Pseudowire Node B Cell- Tunnel site LSP PE PW frame 4G payload (L2 protocol) eNB, BS PW Label Inner Label T-LSP Label Outer Label MPLS Label Stack   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 42
  • 43. Multi-Segment PW for Backhaul Cell Site Ethernet, TDM, ATM MS-PW 2G BTS MPLS Aggregation MPLS 3G Access Pseudowires Node B Tunnel LSP T-PE S-PE 4G Hub MTSO eNB, BS T-PE 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 43
  • 44. 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 Service Level carriers e.g ATM OAM, MAC-Ping –  Reduce troubleshooting time and therefore reduce VLL / PW Level OPEX e.g VCCV, PW status –  Enable delivery of high-margin premium services which require a short restoration time Tunnel LSP Level   Top level requirements e.g LSP ping –  Provide/co-ordinate OAM at relevant levels in IP/ MPLS network –  Proactive and reactive mechanisms, independent at all levels 45
  • 46. OAM and Service Assurance: Mobile Backhaul Test Service Latency, Jitter, Packet Loss and Round-trip Delay Operator GUI Schedule a Suite of Tests at Monitor Alerts for Potential OAM Notification Service Activation or Time of Day SLA Violation Calculate SLA Automate On-Demand Test Performance Metrics Suites from Fault Notification OAM Notification (flat file) OSS 2G BTS MPLS RAN MTSO PE 3G L2 AC Pseudowires L2 AC Node B Cell-site Tunnel LSP PE 4G eNB, BS 46
  • 47. Service-Aware OAM Toolkit Cell Site VLL / PW Level Service Level e.g BFD, VCCV, PW status e.g ATM OAM, SDP-Ping 2G BTS MPLS Aggregation MPLS 3G Access Pseudowires Node B Tunnel LSP 4G Hub MTSO eNB, BS Tunnel / LSP Level e.g LSP Ping & Traceroute Quickly isolate and troubleshoot faults to reduce MTTR 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) 47 for performance monitoring, path segment monitoring and alarm suppression
  • 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 48
  • 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 49
  • 50. Virtual Circuit Connection Verification (VCCV) 2G BTS PE1 PSN PE2 4G-3G-2G 3G Node B A GW/ Attachment Pseudowire Attachment HBSC/RNC 4G Circuit Complex eNB, BS Circuit   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 50
  • 51. PW Status Signaling AC defect PW status: AC RX fault AC defect 2G PSN BTS PE1 PE2 4G-3G-2G A GW/ 3G Node B HBSC/RNC Attachment Pseudowire Attachment Complex 4G eNB, BS Circuit Circuit 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 51
  • 52. PW Status Signaling: Multi-segment PWs 2G PW Status BTS MPLS Aggregation MPLS Access Pseudowires 3G Node B Tunnel LSP S-PE T-PE 4G Hub MTSO eNB, BS T-PE Cell Site   PW status signaling also works for MS-PWs   S-PEs: –  Transparently pass remote defect notifications –  Generate notifications of local defects 52
  • 53. MPLS Network Reliability Both node level and network level recovery are required 3G active Node B A GW/ RNC Ethernet standby 4G ATM (IMA) MPLS RAN eNB, BS Network Level Recovery Node Level Recovery  Dual-homing w/o RSTP  Non-stop routing for ALL protocols (LDP,  MPLS FRR OSPF, IS-IS, BGP, multicast, PIM-SM)  MPLS Standby Secondary  Non-Stop Service for ALL services (VPLS,  Sub 50 ms restoration VLL, IP-VPN, IES, multicast)  End-to-end path protection  MPLS extensions to include additional approaches 53
  • 54. Network Level Redundancy for PWs AC redundancy protocol drives Active/standby state of forwarding state of PWs/PEs LAG/APS sub-groups reflected in PW status 3G Node B active PW status A GW/ Ethernet RNC 4G ATM (IMA) MPLS RAN standby eNB, BS Forwarding direction AC redundancy: determined by PW state MC – APS MC - LAG 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 54
  • 55. Packet Synchronization and Timing
  • 56. The Need for Synchronization in Mobile Networks RNC RNC NobeB 1: Radio Framing Mobile Core Accuracy NodeB Network(s) eNB or BS A GW 2 : Handoff Control 3 : Backhaul eNB or BS Transport Reliability   Synchronization is vital across many elements in the mobile network   In the Radio Access Network (RAN), the need is focused in three principal areas 56
  • 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 57
  • 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 58
  • 59. Backhaul Transport Reliability Backhaul network eNB/BS/ A GW/ NodeB/BTS X RNC/ BSC TCP end-to-end windowed transmission   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 59
  • 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 60
  • 61. 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 62
  • 63. MMBI Scope (continued)   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 63
  • 64. Multiple TNLs – Successive Generations of Mobile Architecture Network Specification Transport Network Layer (TNL) GSM/GPRS/EDGE TDM, IP* (2G/2.5G) 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 64 *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) 65
  • 66. Typical 2G and 3G RAN Topology   Star topology enabling communication from BS to Controller and from Controller to BS   Centralized topology 66
  • 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 67
  • 68. MMBI Reference Architecture – 2G/3G 68
  • 69. Generic TNL Protocol Stack – 2G/3G Architecture: Example of SS-PW Deployment TNL TNL TNL TNL TNL PW TNL PW TNL PW LSP LSP LSP LSP LSP LSP LSP L2 L2 L2 L2 L2 L2 L2 L1 L1 L1 L1 L1 L1 L1 L1 L1 L1 L1 L1 MPLS network PE Access P Aggregation P PE network network TNL PW BS RC TDM CSG MPLS MPLS MASG TDM ATM Access ATM Ethernet Node Node Node Ethernet   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) 69
  • 70. Generic TNL Protocol Stack – 2G/3G Architecture: Example of MS-PW Deployment TNL TNL TNL TNL TNL PW TNL PW TNL PW TNL PW TNL PW LSP LSP LSP LSP LSP LSP L2 L2 L2 L2 L2 L1 L1 L1 L1 L1 L1 L1 L1 L1 L1 MPLS network T-PE Access S-PE Aggregation T-PE network network TNL PW BS RC TDM CSG MASG TDM ATM Access MPLS ATM Ethernet Node Ethernet   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) 70
  • 71. MMBI: Timing deployment scenarios Access Aggregation BTS / Node B CSG BTS / Node B MASG MSC 2G A BNG 2 G -3 G MSC 3G Access Edge Gateway Access BS C / RNC A / MPLS Node Node TNL Complex Gb Core Iu-CS TNL mobile Aggregation network BTS / Node B network Access network Iu - CS Gb Iu - PS xDSL, Iu - PS SGSN 2G microwave, Leased Line, PRC SGSN 3G GPON, via Optical Eth GPS (a 1 ) (a2 ) (a3 ) (a4 ) PHY clock (b ) PKT clock (c) (d ) 71
  • 72. IP transformation in mobile networks with evolution to LTE CS Core TODAY Backhaul (TDM/ATM) PS Core Node B RNC SGSN GGSN 1 2 3 4 5 6 7 Radio Backhaul RNC bearer MCS voice and intelligence transition mobility CS and PS Best effort SGSN packet evolve into a Internet moving to to IP/ evolves to to mobility evolves unified all-IP eNodeB Ethernet the SGW e2e QoS into the SGW domain RNC control SGSN control distributed into evolves into the MME/eNB the MME LTE Multimedia Services Backhaul (IP/Ethernet) PCRF MME Service and mobile aware eNB SGW all-IP network PDN GW 72
  • 73. LTE Evolved Packet System (EPS) Backhaul (IP TNL Application) UE EUTRAN EPC Applications IMS Apps eNB S10 HSS MME S6a PCRF Rx X2 S1-MME S11 Gx S5/S8 SGi eNB S-GW P-GW PDN S1-U S5 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 73 HSS: Home Subscriber Server
  • 74. Evolved Packet Core: Overview of components and functionality  eNodeB: Policy, Charging & Rules Function  all radio access functions   Network control of Service Data Flow (SDF) detection, gating, QoS & flow based charging   Radio admission control   Dynamic policy decision on service data flow   Scheduling of UL and DL data treatment in the PCEF (xGW)   Scheduling and transmission of   Authorizes QoS resources paging and system broadcast   IP header compression (PDCP) PCRF   Outer-ARQ (RLC) Policy Decisions PDN Gateway   IP anchor point for bearers   UE IP address allocation   Per-user based packet filtering   Connectivity to packet data network Mobility Management Entity Serving Gateway   Authentication   Local mobility anchor for inter-eNB handovers   Tracking area list management   Mobility anchoring for inter-3GPP handovers   Idle mode UE reachability   Idle mode DL packet buffering   S-GW/PDN-GW selection   Lawful interception   Inter core network node signaling for   Packet routing and forwarding mobility between 2G/3G and LTE 74   Bearer management functions
  • 75. MMBI Reference Architecture - LTE   Flat Topology RANs using IP TNL: Network Specification TNL HSPA+ flat 3GPP R7 IP LTE 3GPP R8   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 75
  • 76. MMBI Reference Architecture – VPLS Use Cases Access Aggregation Core Cell SIte Gateway Mobile (CSG) Aggregation Site Gateway (MASG) BS1 Edge aGW CSG1 Node S1 S3/S4 Access Access S5/S8a SGSN IP TNL network Node Edge IP/MPLS Node IP TNL S1 Core S5/S8a BS2 Aggregation CSG2 S3/S4 network PDN GW S1 network IP TNL S6a S6a Edge HSS BS3 Node CSG3 S1 Access IP TNL network L2VPN MPLS transport network solutions aGW MPLS PE function could be CSG1 integrated into the aGW CSG2 Ethernet VPLS (MME GW, S - GW, ASN GW) CSG3 CSG1 VPLS CSG2 Ethernet VPLS CSG3 Eth PW CSG1 VPLS CSG2 Full mesh VSI CSG3 Spoke PWs CSG1 H - VPLS H-VPLS Note: BS supports Ethernet interface. CSG2 CSG3 One Cell Site Gateway can connect multiple BS. 76
  • 77. MMBI Reference Architecture – L3VPN Use Cases Access Aggregation Cell SIte Core Gateway Mobile (CSG) Aggregation Site Gateway (MASG) BS1 Edge aGW CSG1 Node S3/S4 S1 SGSN Access Access IP TNL S5/S8a network Node Edge Node IP/MPLS S5/S8a IP TNL S1 BS2 Aggregation Core PDN GW CSG2 S3/S4 network S1 network S6a IP TNL S6a HSS Edge BS3 Node CSG3 S1 Access IP TNL network L3VPN MPLS transport network solutions aGW MPLS PE function could be integrated into the aGW CSG1 CSG2 L3VPN (MME GW, S - GW, ASN GW) IP CSG3 CSG1 L3VPN CSG2 IP L3VPN CSG3 MPLS CSG1 VRF CSG2 L3VPN CSG3 Note: BS supports Ethernet interface. One Cell Site Gateway can connect multiple BS. 77
  • 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) 78
  • 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) 79
  • 80. Future Certification Test Suite Development  Ethernet over MPLS  IP over MPLS 80
  • 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 81
  • 82. MPLS in Mobile Backhaul Summary of Success Factors
  • 83. MPLS in Mobile Backhaul: Critical Success Factors   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 83
  • 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. 84
  • 85. Broadband Forum Mobile Backhaul work in progress   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) 85
  • 86. Related Standards Organizations and Consortiums   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 86
  • 87. 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 For more information, educational presentation has been approved by members of the Forum. This Broadband Forum visit us at http:// educational presentation is not binding on the www.broadband-forum.org 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 2G – Second generation mobile network MGW – Message gateway 3G – Third generation mobile network MMBI – MPLS in mobile backhaul initiative 4G – Fourth generation mobile network MME – Mobility management entity AG – Access gateway MPLS – Multiprotocol label switching aGW– Access gateway MPLS-TP – MPLS Transport Profile ASN – Access service node MSC – Mobile switching center BS – Base station MTSO – Mobile telephone switching office BSC – Base station controller Node B – Base station transceiver with UMTS/WCDMA BTS – Base transceiver station PCRF – Policy and charging function CDMA – Code division multiple access PDN – Packet data network CS – Circuit switched PDSN – Packet data serving node CSG – Cell site gateway P-GW – PDN gateway EDGE – Enhance data rates for GSM evolution PS – Packet switched eNB - – 4G/LTE base station PW – Pseudowire eNode B – 4G/LTE base station RAN – Radio access network EPC – Evolved packet core RNC – Radio network controller EUTRAN – Evolved UTRAN RSVP – Resource reservation protocol EV-DO – Evolution data optimized SGSN – Serving GPRS support node FEC – Forwarding equivalence class S-GW – Serving gateway FRR – Fast re-route TE – Traffic engineering GGSN – Gateway GPRS support node TNL – Transport network layer GPRS – General packet radio service UE – User equipment GSM – Global system for mobile communications UMB – Ultra mobile broadband GW – Gateway UMTS – Universal mobile telecommunications system HSPA – High speed packet access VLAN – Virtual local area network HSS – Home subscriber server VPN – Virtual private network LSP – Label switched path WAC – WiMAX wireless access controller LTE – Long term evolution WiMAX – Worldwide interoperability for microwave access MASG – Mobile aggregation site gateway 88