The Role of MPLS-TP in Evolved packet transport
John Volkering
Consulting Engineer
Ericsson Product Area IP& Broadband

OPTICAL
OPTICAL
Sonet
SDH
Ethernet
IP
ACCESS AGGREGATION EDGE CORE
Today’s transport architectures
the layered approach
ENTERPRISE
MTU
RESIDENTIAL
METRO
10,000s 1,000s 100s 10s 10s

evolved transport network
A prospective view Transport characteristics
. Long term statically provisioned bi-directional paths
. Support for different transport types, such as packet and TDM
. Pre-determined backup paths (predictability)
. Highly automated operations environment
. Strong reliance on automated OAM and fault management systems

ACCESS
10,000s
AGGREGATION EDGE CORE
Network LAYER evolution
Technology consolidation
METRO
OPTICAL
SDH
Ethernet
ENTERPRISE
MTU
RESIDENTIAL
xWDM
SDH
TDM
Ethernet, ATM, FR
IP
MPLS
IP
OTN/xWDM
IP/Ethernet
MPLS
TECHNOLOGY
AND
SYSTEM
CONSOLIDATION
FOR
NETWORK SIMPLIFICATION

. MPLS-TP objectives:
. Enable MPLS to be deployed in a transport network and operated in a similar manner to existing transport technologies (SONET/SDH)
. Enable MPLS to support packet transport services with a similar degree of predictability and reliability to that found in existing transport networks
. MPLS-TP extensions are fully compatible with existing MPLS specifications and newly defined protocols are included in IETF MPLS set MPLS TP

TP
Extensions
MPLS-TP Additional
MPLS Functionality
MPLS-TP is a
subset of MPLS
MPLS-TP and the MPLS Architecture

MPLS-TP Additional Functionality
Based on Transport Requirements

Transport-like OAM
. In-band OAM
. Performance monitoring for SLA verification
. Alarms and Fault Notification

Transport-like Operations
. Static Provisioning
. Operation through NMS
. Bi-directional paths

Transport-like Resilience
. Sub-50 ms OAM driven protectionswitching
. Linear protection(1+1, 1:1, 1:N)
. Ring protection

MPLS-TP Fundamentals
. RFC 5654 specifies the general MPLS-TP fundamentals

Transport Centric Operational Model
Not dependent on distributed Control Plane
Protection Switching Triggered by OAM
No dependencies on Signaling or Control Plane
Transport Optimized OAM
Operations, Administration, Maintenance
Connection-Oriented
Must also support Bi-directional Paths
Standard MPLS Data Paths
Same forwarding mechanisms (label push/pop/swap)

Transport-Like OAM

. All OAM functionality needs to be in-band
. OAM packets are sent over the data plane
. Takes same path as the user payload
. No out-band signaling component
. OAM functionality must not depend on IP forwarding LSP
. ACh is used for OAM on all levels
. Using the PW-ACh for Pseudowires
. RFC 4385
. Using a Generic ACh (G-ACh) for LSPs
. RFC 5586 User data packets OAM packets LSP
. A dedicated channel associated with the data path is created for the OAM packets
. Known as an Associated Channel (ACh) Transporting OAM Packets

PW Ach & Generic ACh

. PW ACH
. Between PW Label and OAM payload
. Channel Type indicates type of OAM packets PW-ACh according to RFC 4385
. Generic ACH
. Reusing structure from PW ACH
. G-ACh Label (GAL) provides alert based mechanism to identify presence of the ACH G-ACh according to RFC 5586
. OAM Features Portion of LSP
. Continuity Check (CC)
. Proactive liveliness monitoring
. Connectivity Verification (CV)
. Verifying end-point
. Delay and Loss Measurements
. Fault Notification, Fault Isolation and Diagnostics

Secure Connection-Oriented Paths
Connection-Oriented
Must also support bi-directional paths
. MPLS-TP excludes some MPLS options to ensure connection-oriented paths and consistent OAM operation
. Equal Cost Multi Path (ECMP) . excluded
. MultiPoint to Point (MP2P) LSPs . excluded
. Penultimate Hop Popping (PHP) . disabled by default
. MPLS-TP supports the following LSP types:
. Uni-directional Point-to-Point (P2P)
. Uni-directional Point-to-Multipoint (P2MP)
. Bi-directional P2P
. Associated and co-routed

MCC/SCC
MCC/SCC
MCC/SCC
ACH
Transport-Like Resilience
Protection Switching Triggered by OAM
No dependencies on Signaling or Control Plane
.Comprehensive set of recovery mechanisms
.OAM triggered protection mechanisms are standardized within MPLS-TP
.Existing MPLS & GMPLS mechanisms may also be used
. Similar functionality across PWs, LSPs, SPMEs, and sections

Protection
. Protection triggered by data plane OAM
. Linear protection
. Dedicated 1+1 (2 concurrent traffic paths)
. Dedicated 1:1 (one active and one standby path)
. Shared 1:N (many active paths share one standby)
. Additional Ring Protection mechanisms
. Protection State Coordination (PSC) to sync the nodes
Recovery path
Working path
Selector
Bridge
Selector
Bridge
Example: Dedicated 1:1
Protection Switching Triggered by OAM
No dependencies on Signaling or Control Plane

OPTICAL
OPTICAL
Sonet
SDH
Ethernet
IP
ACCESS AGGREGATION EDGE CORE
Evolved Transport Network
Technology Fit
ENTERPRISE
MTU
RESIDENTIAL
METRO
10,000s 1,000s 100s 10s 10s
MPLS-TP IP/MPLS
OPTICAL
OPTICAL
Sonet
SDH
Ethernet
IP
ACCESS AGGREGATION EDGE CORE
Evolved Transport Network
Service Segmentation
ENTERPRISE
MTU
RESIDENTIAL
METRO
IPVPN
E-Line
E-Tree
E-LAN
End 2 End
Service
Fiber
Topology
Edge/Aggregation: 1000s of sites Core: 10s of sites
P2P/P2MP PWE
Service
Topology
E-Line
E-Tree
E-LAN
IPVPN
L2 Edge
L3 Edge
OPTICAL
OPTICAL
Sonet
SDH
Ethernet
IP
ACCESS AGGREGATION EDGE CORE
MPLS-TP and IP/MPLS
Interworking
. End-to-End Pseudo-wire can provides end-to-end OAM
across different domains
ENTERPRISE
MTU
RESIDENTIAL
METRO
10,000s 1,000s 10s 10s
PE
. MPLS-TP and IP/MPLS interworking can take place anywhere in the transport network MPLS LSP / PWE3 Statically Provisioned MPLS LSP PWE3 Dynamically Provisioned Ethernet PWE3 MPLS-TP LSP MPLS LSP

Evolved packet transport

summary
. Transport networks are under transformation
. MPLS-TP, OTN and P-OTP will enable the transport evolution with simplicity, efficiency and scalability
. MPLS-TP is MPLS.
. It is optimized for transport neworks paradigm
. MPLS-TP provides a similar degree of predictability, reliability and OAM to that found in existing SONET/ SDH transport networks