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Transcript of 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
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 – 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: 114 kbps UL: 114 kbps
DL: 384 kbps UL: 384 kbps
DL: 1.8-7.2 Mbps UL: 384Kbps
GSM GPRS
HSDPA Rel 5
UMTS (W-CDMA) R99
DL: 384 kbps UL: 384 kbps
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
IP/MPLS Backbone Radio Access Network
Multi-phase MPLS migration into RAN Transport
Hub Cell Site
2G – TDM/IP 3G – ATM/IP
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
IP/MPLS Backbone Radio Access Network
Multi-phase MPLS migration into RAN Transport
Hub Cell Site
2G – TDM/IP 3G – ATM/IP
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
for all Technologies
MPLS Aggregation
for all Technologies
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
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)
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
MPLS Aggregation MPLS Access
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
MPLS Aggregation MPLS Access
Hub
Cell Site
MTSO
T-PE
PW Status BTS
2G
eNB, BS 4G
Node B
3G
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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
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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
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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)
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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
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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
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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
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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)
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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
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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
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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
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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
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MMBI Reference Architecture – VPLS Use Cases
IP TNL
Mobile Aggregation Site Gateway
(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
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MMBI Reference Architecture – L3VPN Use Cases
IP TNL
Note: BS supports Ethernet interface. One Cell Site Gateway can connect multiple BS.
Mobile Aggregation Site Gateway
(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
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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)
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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)
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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
MPLS in Mobile Backhaul
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.
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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
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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.
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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