OFC/NFOEC 2013 Optical Network Applications and Services (Tutorial) March 20, 2013

MPLS-TP: Overview and status

Yoshinori Koike
978-1-55752-962-6/13/$31.00 2013 Optical Society of America

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Agenda
1. Drivers of packet transport technologies and their applicability
2. Definition of MPLS-TP

3. Layer 2 technologies
4. Additional functions in MPLS-TP 5. History of MPLS-TP standardization 6. Deployment scenarios of MPLS-TP technology and network 7. Promising multi-layer converged transport network

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1. Drivers of packet transport technologies and their applicability

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Promising packet transport network

As IP services drastically increase, Carriers and ISPs have been willing to efficiently accommodate their client traffic. Packet networks have been rapidly expanding. Following this demand, Ethernet and MPLS have been introduced to their networks; however, they did not have sufficient maintenance capabilities such as trouble shooting, and alarm reporting. Current transport technologies, such as SDH and OTN, equip carrier grade OAM and protection. This results in strong demand for packet transport technology in carrier networks.
Characteristics of packet transport network Reduction of CAPEX/OPEX => Multi-service => Traffic engineering/ Recovery Carrier grade operation Guarantee of quality Timing distribution => => => => => Ethernet-IF, low power consumption, Various clients (Ethernet, SDH, PDH, ATM, MPLS Traffic engineering Protection OAM, transport-oriented operation QoS SyncE, time & phase distribution

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Current trends in packet transport network

Packet transport network has been replacing existing SONET/SDH-based transport networks and expanding new packet based service as well as legacy transport network services. Frequency distribution is another requirement, particularly when SDH is replaced with packet transport network(PTN)
Legacy Service Legacy Service TDM CSM Efficient accommodation of IP service Taking over legacy service Clock path Fixed service Mobile service PSTN Dedicated line

Before

CSM

Replacement (cost reduction) IP-based service IP-based service Packet transport network Legacy service

After
Legacy service CSM

Clock path CSM

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Applicability of packet transport technologies

Packet transport technologies could fit and be introduced into any part of a network from access, metro/aggregation and core. For example, one scenario is to keep IP/MPLS core network and introduce MPLS-TP into metro network.
Access NW
Mobile NW

Metro/aggregation NW

Core NW

VoD, SIP

Home NW

IP-TV

Business customers NW

PTN
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2. Definition of MPLS-TP

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Relationship between MPLS and MPLS-TP

MPLS-TP (Transport Profile) consists of MPLS technology excluding unwanted functions and additional functions from transport technologies such as SONET/SDH.

MPLS
Existing MPLS Before standardization of MPLS-TP ECMP LDP/Non-TE LSPs IP forwarding PHP
Common features MPLS forwarding PWE3 architecture

Extensions of existing MPLS such as RFC6374 (delay and loss) and RFC5586 (G-ACH)

MPLS-TP
Additional functions from transport technologies

ECMP: Equal Cost Multi Path PWE3Pseudo Wire Emulation Edge to Edge PHP: Penultimate Hop Popping
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Additional features of MPLS-TP requested in transport network

One key architecture differences is separation between C-plan and D-plan. In MPLS-TP, even if fault occurs in C-plane, there is no impact on D-plane. Three other major functions are added to original MPLS: Carrier grade maintenance capability using OAM Simple network operation using NMS Robust and reliable service based on protection

Key features in MPLS-TP based on current transport technology

Transport architecture Independence between C-plan and D-plan Transport OAM Transport network operation In-band OAM channel Network Management System Fault management Static provisioning Performance monitoring Traffic engineering New maintenance model (Per-interface mode) Transport protection Sub 50-ms protection Linear protection Ring protection
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MPLS-TP operation and protection

NMS management

C-plane (option)

C-plane (option)

C-plane (option)

PE NE Customer Edge Client NE

P NE
Psudowire (static or dynamic) MPLS-TP LSP (static or dynamic) section Client traffic section

PE NE

Customer Edge Client NE

Permanent Bridge Protection Working LSP Protection LSP

Selecter Bridge

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Client accommodation (Pseudewire technologies)

Pseudowires (PWs) accommodate/adapt multi-technology clients, such as Ethernet/SDH/ATM, in MPLS-TP In other words, PW is a mechanism to emulate telecommunication services such as Ethernet, ATM, SDH, and dedicated line in MPLS-TP network Dedicated line PW based EthernetSDH service ATMFR etc PW Payload

Emulated service section

PW segment
Client layer MPLS-TP layer PE1 Tunnel LSP PE2

PW label

CE1

AC

CE2

LSP label CE: Customer Edge PE: Provider Edge

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Client accommodation (Pseudewire technologies) Contd.

PWE3 is extended to single segment PW to multi-segment PW. It may be possible to swap tunnel protocols in PW layer. There is some discussion about whether overlapping of MS-PW switching function is necessary.

Multi-segment PW model
PWE MPLS-TP layer
Client layer

PWE Client layer

PW label switching (Swapping)

PW Payload

PW Payload PW label

Payload CW 10 60

Payload CW 20 80

Multi segment PW PW label MPLS-TP LSP label Layer T-PE1 S-PE T-PE2

LSP label

T-PE: Terminating Provider Edge S-PE: Switching Provider Edge CW: Control Word
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3. Layer 2 technologies

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Difference in original concept of data-plane between Ethernet and MPLS

Ethernet data-plane is originally capable of automatically establishing MP2MP topology and connectionless technology based on MAC learning and bridging. VLAN-tag was introduced after MAC learning and bridging and defined for boundary of broadcast domain (not allowed to be swapped in terms of standardization). MPLS is capable of establishing P2P and P2MP connection-oriented technology. MPLS label is originally designed for swapping.
Tag is used as User Identification and definition of broadcast domain Tag swapping is not standardized

Ethernet
DA SA S-tag C-tag T/L

VLAN
-1

VLAN
-2

VLAN
-3

S-VID DEI

PCP

Label swapping is standardized

10 20

MPLS(-TP) MPLS router

Label

TC S

TTL

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Comparison between Ethernet and MPLS

Ethernet is applied for automatic MP2MP topology establishment as well as P2P/P2MP topology establishment. MPLS is applied for explicit provisioning of P2P and P2MP connection, particularly for traffic engineering feature.

Ethernet 1 2 3 Multi-point to Multi-point Data-plane auto-discovery Swapping in terms of standardization Yes Yes (MAC learning and Bridging) No (VLAN-tag)

MPLS No No (needs C-plan) Yes (LSP label)

4
5

Number of layers
Client support

C-tag, S-tag, I-tag, Btag

Label stacking

Ethernet, SONET/SDH Ethernet, SONET/SDH, PDH, ATM, Frame relay

6
7

Possibility of looping in dataplane

Make-before-break

High
No

Low (in static)

Yes
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Comparison between MPLS and MPLS-TP

Management-plane (NMS)-based central operation is key feature not supported by original MPLS (RFC5654 R17&19). Independence between data-plane and control-plane is another key feature in MPLS-TP (RFC5654 R23&47). MPLS-TP will be included as part of MPLS in near future, but MPLS and MPLS-TP are technically different at moment. Many common parts can be seen in data-plane. Regarding OAM, MPLS and MPLS-TP are quite different, and interoperability is almost impossible. Difference between MPLS and MPLS-TP in data-plane and OAM

Different characteristics between MPLS and MPLS-TP

Data-plane/Transport-plane Item
No control plane Separation between C-plane and D-plane NMS-based central management Protection Label 13 (GAL)

MPLS
No No No No No

MPLS-TP
Yes Yes Yes Yes Yes
Label 14 IP encap VCCV
IP forwarding, label merging, PHP

Label Forwarding

Protection

OAM (OAM identification)

Label 13 (GAL) G-Ach

Current MPLS

MPLS-TP

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One aspect: MPLS-TP in core transport network

Ethernet is superior in terms of MPtoMP aspects and easy connectivity. Reliability is guaranteed based on OAM extension to some extent. MPLS(-TP) is more reliable and suitable in terms of its original traffic engineering concept. It does not rely on MAC learning or FDB flashing. MPLS-TP is very useful in core transport network if functions of transport network are required for reliability and enhanced maintenance capability

An example of MPLS-TP applicability

Metro/Aggregation NW IP/MPLS or MPLS-TP

Core transport network NMS Metro/Aggregation NW

Ethernet Metro/Aggregation NW Provider Bridge NW (IEEE802.1ad) Ethernet (PB

MPLS-TP Provider Backbone Bridge NW (IEEE802.1ah) Ethernet (PBB

Provider Bridge NW (IEEE802.1ad)

Ethernet (PB
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4. Additional functions in MPLS-TP

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Effective maintenance capability: Prompt fault localization

Carrier grade means extending maintenance features and operational tools rather than adding new service functions for our customers in transport service After starting to provide our services, quality of maintenance service is only factor defining value of carrier. Prompt fault localization is one of most essential factors, i.e., to identify what is going on, and where, when, and how it happened. Memory Error? Unexpected fault? Unidentified glitch?

Customer misconfigura tion

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Customer NE1
Customer domain

P1

P2

P3

P4

P5

Customer NE2
Customer domain

Carriers domain

Lot fault? Misconfiguration? Traffic overload? Equipment fault

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1) New maintenance model: Per-interface model

Per-interface OAM model is supported for improving maintenance. Traffic monitoring is possible with both Ingress IF and Egress IF cards in one box. Fault localization capability is significantly improved compared to current MPLS technology.
Existing MPLS (Per-node model) Newly supported in MPLS-TP (Per-interface model) Ingress Egress

MIP

MIP

MIP In

FW

MIP out

Intermediate node

Intermediate node

MEP

MEP

MEP Up

FW

Down

Down

FW

MEP Up

Source/Destination node

Source/Destination node

Source/Destination node
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Refer to: ITU-T G.8121, G.8151, RFC6371 and draft-

FW: Forwarding Engin

Case 1) Difference in fault location scenario between two approaches :Packet loss at Customer NE Operators
Per-node model Customer NE1 Customer domain PW/LSP MEP1 On-demand CV Per-interface model MIP1 NE1 NE2 NE3 Administrative domain Customer NE2 ? ? ? Customer domain

P1

P3

P5

MEP2
OK

Packet Loss Packet

Loss

NE1 P1 P2

NE2 P3 P4

NE3 P5 OK P6 OK ? Customer domain Legends Interface OK OK Forwarding Engine MIP Customer NE2

Customer NE1
Customer domain PW/LSP

MEP1

MIP1

MIP2

MIP3

MIP4

MEP2

(1) On-demand CV (2)

MEP
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Case 2) Difference in fault location scenario between two approaches

Per-node) NE1 NE2 NE3 Operators Administrative domain

Customer NE1

P1

P3

P5

Customer NE2 Customer domain

?
Customer domain PW/LSP MEP1 On-demand CV Per-interface) Customer NE1 NE1

MIP1

MEP2
NG

Packet Loss Packet

Loss

NE2 P2

NE3 Customer NE2 Customer domain Legends Interface OK NG Forwarding Engine MIP

P1

P3 ?

P4

P5

P6

OK
Customer domain PW/LSP MEP1

MIP1

MIP2

MIP3

MIP4

MEP2

(1) On-demand CV (2)

MEP
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Case 3) Difference in delay measurement scenario between two approaches

Per-node)

NE1
P1

NE2
P3 Operators Administrative domain

NE3
P5

Customer NE1
Customer domain PW/LSP

Custom er NE2 Customer domain

MEP 1
Per-interface)

MIP1
Measurable section

MEP 2
NE3

Delay of this section is not measurable

NE1
P1 P2

NE2
P3 P4

Customer NE1
Customer domain PW/LSP

P5

P6

Custom er NE2 Customer domain

Operators Administrative domain

MEP 1

MIP1

MIP2

MIP3

MIP4

Measurable section

MEP 2

Legends
Interface Forwarding Engine

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MIP MEP

Distinction between communication and equipment alarms

Clear definition of ingress and egress MPs makes operational system follow transport characteristic and makes it possible to precisely investigate LSP status for customer service. Status of equipment (NE) largely depends on forwarding engine. That of communication part (between NEs) mainly depends on interfaces. NE1 NE2 NE3 Legends Custom er NE
Type 1 (MPLS-like) Interface Forwarding Engine MIP MEP

On-demand CV

Operators Administrative domain

Type 2 (TDM-like)

(1) (2) (3) (4) (5)

No

YES

YES
No

YES YES YES

YES

YES
No

General alarm classification in transport network Equipment alarm Communication alarm

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2) Hitless/in-service path segment monitoring

There is no requirement and solution in standard which make it possible to locate degraded point in hitless manner/without service interruption when performance degradation is detected. Hitless and temporal segment monitoring is on-demand OAM function to quickly localize degraded point, which is under development in standard.

Segment monitoring function is necessary in Delay Measurement (DM) and Loss Measurement (LM) (DM and LM are supported only between MEP and MEP, not supported between MIP and MEP/MIP) : See use case 1 on next slide Diagnostic test and on-demand CV should also be able to be conducted from intermediate point of configured transport path. : See use case 2 on next slide

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Use cases of hitless segment monitoring

Use case 1) DM and LM Packet Delay/Loss
NE2(LSR1) NE3(LSR2) NE4(LER2) CE2 NE1(LER1)

CE1

MEP MIP MEP

Transport path

Segment monitoring 1 Segment monitoring 2

No Fault
Detect Fault

Use case 2) Diagnostic test and on-demand CV Originator of test packets

NE2(LER1) NE3(LSR2)

Cost effective small box (Support subset of functions) NE4(LER2)

NE1 Segment monitoring 1 Segment monitoring 2

NE5

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5. History of MPLS-TP standardization

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Current status of ITU-T MPLS-TP-related Recommendations

Type of Recommendation Architecture OAM Interface Linear protection Ring protection Equipment functional block Equipment management requirements Equipment management info model (mgmt protocol independent) DCN Terms and definitions Approved Recommendations
* Revised as MPLS-TP from T-MPLS G.8132 G.8121* G.8151* G.8152 G.7712 G.8121.1 G.8121.2 G.8112* G.8131 (or G.8131.1&G.8131.2)

Common
G.8110.1

Only for PTN

Only for PSN

G.8113.1

G.8113.2

G.8101
PTN: Packet Transport Network PSN: Packet Switch Network(IP/MPLS) AAP: Alternative Approval Process TAP: Traditional Approval Process
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Progress of MPLS-TP OAM standard

2008: Joint work on MPLS-TP standardization was agreed in 2008. Two communities of interest advocated different approaches to develop MPLSTP OAM solution: ( G.8113.1 (Ethernet-based OAM) and G.8113.2(IP/MPLS based OAM). Feb. 2011: G.8113.1 was determined in ITU-T by vote. Nov. 2011: G.8113.2 based OAM solutions became RFCs, and G.8113.1-based OAM solution was not allowed to progress in IETF due to lack of rough consensus. Dec. 2012: Deadlock on MPLS-TP in ITU-T SG15 meeting was partially broken by approving G.8110.1 by consenting to G.8121 and G.8151. However, G.8113.1 was escalated to WTSA-12. Sep. 2012: G.8113.2 was determined and also sent to WTSA-12. Both meeting recommendations were sent to WTSA-12 for approval. Nov. 2012: Both G.8113.1 and G.8113.2 were approved in WTSA-12 and code point for G.8113.1 was assigned by IANA

Both G.8113.1 (Ethernet based OAM) and G.8113.2 (IP/MPLS based OAM) have been standardized.
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How to differentiate OAM protocol solutions?

MPLS-TP OAM protocol solutions: Generally differentiated by channel type in extended Associated Channel Header(ACH) Some MPLS-TP OAM protocols use other channels, such as existing PW ACH and IP encapsulation,

32 bits
Label Value |TC|S|TTL GAL(13)

32 bits
|TC|S| TTL

32 bits
0001|ver |rsv|Channel Type

ACH-TLV Header

ACH-TLV

LSP label GAL

MPLS label header Generic Associated Channel Label (LSP label identifying OAM packet : label value 13), Associated Channel Header (same as PW ACH but generalized) Channel Type defines OAM protocol solution ACH-TLV (Option, Src/Dst address, Authentication, etc.) G-ACh message (depending on each OAM protocol solution using G-ACh)
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ACH
ACH-TLV G-ACh Msg.

OAM functional requirements in MPLS-TP (RFC5860)

OAM functions are most important key MPLS-TP technologies to achieve carrier grade operation in transport networks
OAM functional requirement 1 2 3 4 Continuity Checks Connectivity Verifications Route Tracing Diagnostic Tests Lock Instruct Lock Reporting Alarm Reporting Remote Defect Indication Client Failure Indication Packet Loss Measurement Packet Delay Measurement Abbr. CC CV RT DT Function Monitor liveliness of transport path Determine whether or not it is connected to specific end point(s) of transport path Discover intermediate (if any) and end point(s) along transport path Conduct diagnostic tests on transport path (estimating bandwidth, performing loop-back (LB) function of all data and OAM traffic (data-plan LB)) Instruct its associated end point(s) to lock transport path Report lock condition from intermediate point to end point of transport path Report fault or defect condition to end point of transport path Report fault or defect condition to its associated end point Propagate information pertaining to client defect or fault condition Quantify packet loss ratio over transport path Quantify delay of transport path (1-way and 2-way)
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5 6 7 8 9 10 11

LI LR AR RDI CFI LM DM

Mappings between RFC and Recommendations on OAM solution

One I-D (Doc. No6) corresponds to G.8113.1(PTN OAM) was submitted as I-D , but solution was not allowed for developing in IETF 5 MPLS-TP OAM solution drafts are related to G.8113.2(PSN OAM) in G.8113.2
ITU-T MPLS-TP OAM Recommendations 1 2 3 PTN G.8113.1 PSN G.8113.2 OAM solution RFC Channel type Status

None:
(Discussed in draft-bhh-mpls-tp-oam-y1731)

0x8902 G.8113.1

(I-D)

MPLS Fault Management Operations, Administration, and Maintenance (OAM) Proactive Connectivity Verification, Continuity Check and Remote Defect Indication for the MPLS Transport Profile MPLS On-demand Demand Connectivity Verification and Route Tracing

0x0058 Fault OAM 0x0022 MPLS-TP CC message 0x0023 MPLS-TP CV message 0x0025 On-Demand CV 0x000A DLM 0x000B ILM 0x000C DM 0x000D DLM+DM 0x000E ILM+DM) 0x0026 LI

RFC6427 RFC6428

RFC 6426

Packet Loss and Delay Measurement Profile for MPLS-based Transport Networks (profile of draft-ietf-mpls-loss-delay)

RFC6375 (RFC6374 )

MPLS Transport Profile Lock Instruct and Loopback Functions

RFC6435
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Differences between PTN OAM and PSN OAM solutions

G.8113.1(PTN) OAM solution focusing on MPLS-TP OAM-specific requirements based on Ethernet OAM mechanism G.8113.2(PSN) OAM solution covering IP/MPLS-oriented requirements for compatibility MPLS-TP OAM Requirements IP/MPLS Requirements
1. G.8113.1

LR
CC

AR

2. RFC6427 (Fault OAM )

Link Down Indication

Configurable message transmission interval

3. RFC6428 (CC message and CV message)

Configurable message transmission interval Configurable message fault detection interval Timer negotiation In-service parameter change (P/F bits)

CV

RDI

CC/CV interleaved (CV only is not possible and interval is only one per second) 4 channels (G-ACH, VCCV(v4 and v6), UDP/IP 2 mode of operations ( Independent and fate sharing)

LM

DM

LM

DM

5. RFC6375 (DLM, ILM, DM, DLM+DM, ILM+DM)

LM&DM combined modes (Direct and inferred packet loss and delay measurements) Two types of LM formats (32 and 64 bits) Two types of DM formats (PTP and NTP)

DT(Thrpt 1)

4. RFC6426 (On-Demand CV)

4 channels (G-ACH, VCCV (v4 and v6), UDP/IP

CV LI

RT DT (DP-LB)

Return codes

Target FEC stacks

Downstream mapping OAM solutions for PTN OAM solutions for PSN

6. RFC6435 (Li)
LSP ping ext

Proactive OAM functions On-demand OAM functions IP/MPLS requirements

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Differences between MPLS-TP OAM Recommendations

Differences between two stem from differences in history, architecture, technology, and previous experience. Ethernet and IP/MPLS are two different major drivers for transport networks. Operators can choose necessary OAM solution on basis of their network development scenarios.
Two OAM solutions G.8113.1 (PTN: Y.1731 based OAM) YES (except for LI and Dataplane LB) Simple (Transport experience) Ethernet OAM G.8113.2 (PSN: Extension of BFD&LSP Ping +performance) YES

MPLS-TP OAM requirements Characteristics as tool(s)

Easily extended from IP/MPLS router (Control experience) IP/MPLS OAM

Preferred compatibility

PTN: Used to add packet transport capability to existing circuit switched (SDH/OTN) transport network PSN: Used to provide packet transport capability to existing IP/MPLS network
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6. Deployment scenarios of MPLS-TP technology and network In terms of OAM solution

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Typical scenario for PTN: Replacing legacy transport network

Migration from legacy transport network
NMS

Ethernet ATM PDH

SDH

Co-routed bidirectional PtoP. Optionally Unidirectional PtoMP. Suitable with Ethernet/transportbased OAM Scalable OAM, easy operation and centralized NW management system (similar to legacy transport NMS) No need of IP layer and IP functions

Legacy network (SDH etc.) NMS

Ethernet

Replacing legacy Nodes

Transport node without MPLS-TP
Transport node with MPLS-TP

ATM PDH SDH

MPLS-TP network
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Typical scenario for PSN: Upgrading/extending IP/MPLS router IP/MPLS upgrade/migration

PE router
Ethernet

IP/MPLS

P router
PE router PE router

PE router P router

Co-routed/Associated bidirectional PtoP, Unidirectional PtoP, and PtoMP. Compatible OAM with IP/MPLS and PW such as LSP-Ping, MPLSBFD, VCCV, and VCCV-BFD IP layer and IP functions necessary for LSP ping at least

Upgrading P routers/ Replacing P routers

P router without MPLS-TP

Ethernet

IP/MPLS

P router with MPLS-TP

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Summary of possible deployment scenarios

Two MPLS-TP deployment scenarios are introduced. Ethernet-friendly approach and IP/MPLS-friendly approach are considered. (Called PTN and PSN, respectively)

Scenario 1

General prioritized preference -Transport network experience (Ethernet OAM) -Static and centralized configuration -Could be extended to converged NW operation mainly based on management plane -IP/MPLS compatibility (BFD, LSP Ping) -Dynamic and distributed configuration -Could be extended to converged NW solution mainly based on control plane

Type PTN

PSN

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7. Promising Multi-layer converged transport network

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Solution: Multi-layer and multi-technology convergence: NW optimization and NE convergence MPLS-TP makes transport networks flexible and more efficient 100G interface introduction is driver for drastically changing network structures to reduce cost in conjunction with energy efficiency Optimization of entire transport network is key to achieve objectives Minimized multi-layer and multi-technology converged transport networks are promising solution
Edge IP router/ switch

Current
Many 10G wavelengths and fixed bandwidth
Relay router/ switch

Edge IP WDM/ router/ OADM switch

100G based on POTS

Edge IP router/sw itches

(3) Large capacity physical link and adaptive and efficient bandwidth allocation by packet transport
POTS POTS

Many kinds of network systems

Many interMany interconnections by connections due many to many EMS/NMS

EMSs/NMSs

(1) Minimized multilayer and multitechnology converged transport networks

(2)Easy operation by (2) Easy operation with converged equipment by converged equipment fewer EMS&NMS and fewer EMSs & NMSs

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1) Example of reduction of core router/switches

In NW model below, 50% reduction in equipment cost may be possible by applying packet optical transport solution. Main factors are router equipment and IF cost reduction. Other costs, such as enhanced OAM and operating system, are not included in estimate. Current network 100
DWDM DWDM

Future packet optical transport network About 50%

CR
DWDM

CR
DWDM

POTS

POTS

DWDM

DWDM

CR
DWDM

CR
DWDM

POTS

POTS

Router 100G-IF Packet IF100G-IF

DWDM DWDM

NNI 100G-IF

POTS

POTS

3R-NNI 100G-IF

ER

ER

Optical SW
Optical SW+ Packet SW

ER

ER

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2) Example of topology-free flat transport network

Topology-free flat transport networks enable operators to efficiently and simply set path for client equipment. This improvement may depends on current network structure of each operator.

OADM

OADM

POTS

POTS

OADM

OADM

DWDM

DWDM

POTS

POTS

Operator 1
DWDM DWDM

Operator
OADM OADM

1. Several operators (NMSs/EMSs) to one operator (NMS/EMS) 2. Manual design in several layers and domains to automatically design in converged layers

POTS

POTS

Operator 2
OADM OADM

POTS

POTS

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3) Example of unified fault and degradation management across layers

Efficient fault localization is key feature in multi-layer converged network managed by unified NMS. Inter-layer (or Inter-protocol) relationship, in particular OAM, is also important: Quick fault localization by inhibiting alarm storms, quick recovery of efficient AIS and so on.

Layer-independent NW

Multi-layer converged network

Virtual switch unit Physical switch unit Fault detection Root fault

No relationship between layer dependency

Interaction between layers would make fault detection time shorter

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4) Example of unified network resource management

Efficient resource design tool prevents consumption of wasteful

bandwidth and network resources across layers. ODU layer (layer 1) cross-connect or packet layer (Layer 2) switching can be omitted based on situation. Current network Future packet optical transport network

Layer 2

L2 SW

L2 SW

L2 SW

L2 SW

L2 SW

Layer 2 (packet)

Layer 1

SDH

SDH

SDH

SDH

SDH

Layer 1 (ODU)

POTS

POTS

POTS

POTS

POTS

WDM/ Layer 0 ROAdM

WDM/ ROADM

WDM/ ROADM

WDM/ ROADM

WDM/ ROADM

Layer 0

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Summary
Increasing demand for packet transport technology was driver for MPLS-TP technology Key features of MPLS-TP: Separation of Data-plane and Control-plane OAM NMS Recovery (Protection) An OAM solution (G.8113.1(PTN) ) has been standardized. PTN is a simple and transport-oriented OAM solution based on Ethernet OAM. Converged transport network solution based on MPLS-TP is a promising solution for future cost & energy efficient networks
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