PCE – OAM Handler in ABNO: a use case of code

adaptation in flex grid networks

PACE Workshop on “New uses of Path Computation Elements”Vilanova y la Geltru , Spain, June 16th 2014

Francesco PaolucciTeCIP, Scuola Superiore Sant’Anna,

Pisa, Italy

Control <-> Management

• Control plane– Discovery and Routing– Path computation– Signaling– Failure recovery

• Management plane– Network Status and Monitoring– Operation and Administration Maintenance (OAM)– SLA verification

• Interaction between planes– Historical separation or limited interaction (not automatic)– New target: pro-active control automatically driven by

OAM events/ conditions– Active Stateful Path Computation Element in ABNO candidate

object

• Active Stateful PCE– Access to TED and LSP-DB– Stateful computation

• Shared protection computation

• Effective restoration

– Active behaviour• Delegated LSP control• LSP resize, modification• LSP instantiation• Optimization Action Chain

•OAM Handler– Network status supervisor– Monitoring correlations

•Databases– TED, LSP-DB

ABNO architecture

Application-Based Network Operation (ABNO) framework.

“A PCE-based Architecture for Application-based Network Operations”

draft-farrkingel-pce-abno-architecture

PCE in Flexible optical networks• Next flexible transponders will support multiple configurable signal generation @given bitrate

• PCE outputs– Suggested frequency slots (n: central frequency, m: width ) – Suggested modulation format (e.g., DP-QPSK, DP-16QAM)– Suggested FEC / code– Single/multi carrier: type and number of sub-carriers

• Hitless flexible operations driven by active PCE– Defragmentation (change n)– Elastic operations (change m)– Dynamic adaptation (change the code)

• Advanced Action Chain– E.g. Defrag + Elastic expand

TED

Active Solver

PCEP Server

Action HandlerLSP-DB

request

update

action list

PCEP

load

action queue

PCReq-new LSP-elastic operation

PCRep-reply to PCReq

PCUpd-active LSP adaptation

PCRpt-LSP adaptation outcome

PCNtfy-TE updates-QoT degradation-failure events

Chain Example: Shift & Expand

5

PCReq (LSP 1: Elastic bit rate increase)1

2 PCUpd (LSP 2: Shift)

4 PCRpt (LSP 2: Shift OK)

5 PCRep (LSP 1: Elastic increase)

7 PCNtf (LSP 1: Elastic incresae OK) FrequencyLSP 1

1 PCReq message

3 RSVP make before break

5 PCRep message

6 RSVP elastic increase

7 PCNtf message

PCRpt message 4

PCUpd message 2

3 LSP 2 shift

6 LSP 1 elastic increase

LSP 2

Code adaptation for flexi Terabit

• Terabit transmission based on Time Frequency Packing– LDPC coding applied to data– Narrow-filtered subcarriers (faster-than-Nyquist) – Coherent detection and DSP

• Scenario 1– 7 subcarriers @ 160Gb/s– 200 GHz width– 8/9 coding– 1.12 Tb/s bitrate -> 1Tb/s info rate

• Scenario 2– More robust transmission needed– 1 subcarrier added– 4/5 coding– 237.5 GHz width– 1.28 Tb/s bit rate -> 1Tb/s info rate

QoT monitoring and forecast

• Quality of Transmission is monitored at the receiver– Post-FEC BER – Variance of acquired data samples

• Event Forecasting– The variance indicates whether a working limit condition is

approaching– FORECASTING post-FEC errors before they occur– Threshold-based alarm event

• QoT monitor– Responsible of monitoring– Responsible of event ntf– Responsible of alarms

0

0,02

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0,08

0,1

12 14 16 18

"3/4"

"4/5"

"8/9"8/9

4/53/4

Varia

nce

OSNR (dB)

Validation Testbed (PCEP+RSVP)

SSSSSS

Link1 Link2

ADC+Processing

X

TxBVT Rx

Controller

PCCRSVP-TE RSVP-TE

Controller Controller

PCC PCC

ActiveStateful

PCE

QoT monitor

1 - PCNtfy (QoT degradation)2 – PCUpd (LDPC rate adaptation + spectralexpansion)

3 –Path4 –Path

8 –Resv

5 –filter shape(expand)

6 –Resv

7 –filter shape(expand)

9 –LDPC rate adaptation

10 – PCRpt

Pol-Mux

IQ-modulators

Configurable Electrical

Data generation

Tunable carrier comb

BVT Tx

oddch.

evench.

I Q

I Q Pol-Mux

couplers

USBUSBeth

eth

OOK Tx

OOK Rx

PCE-driven code adaptation

• Impairment-aware PCE computes a new code rate:– Extended PCUpd message

– The ERO specifies the code to be applied at ingress/egress node

– LDPC code rate TLV• Alarm triggered by PCEP:

– Novel QoT notify msg– PCE computes the code

– First implementation– PCEP not suitable for OAM

– Path rerouting is the last option

-Receiver transponder id: 1-LSP ownership: 10.0.0.1-Event type: excessive BER value (1)

UPDATE (PCUpd) MESSAGEREPORT (PCRpt) MESSAGE

QoT object

LSP id: 1; src IP: 10.0.0.1 LSP object

-ERO subTLVLDPC code rate: 3/4 (adaptation)

-Flexgrid labeln: -44 -> f=192.825THzm: 19 -> width=237.5GHz (expansion)

ERO object

QoT object

UPDATE (PCUpd) MESSAGE

Hitless data plane operations

• To apply the new coding– Configurable electrical encoder at transmitter, triggered upon

RSVP-TE session is finished– In the overhead, a preamble of each data block includes a 3-bit

field to communicate the code to be applied to the next block– Receiver processes next incoming data block with the new coding– Code adaptation performed with no traffic disruption

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OAM infrastructure

• OAM Agent located at the receiver– OAM session per LSP (per receiver card)

• Hierarchical OAM Agent – Local Agent (node, link, network device…)– Aggregation Agent (area, domain…)– Local correlations when applicable – Scalable design

• Proposed OAM protocol: NETCONF– Support of Asynchronous Notifications (RFC 5277)– TCP connection assures reliability– Hierarchical architecture reduces number of connections at

Handler– Native solution for OAM YANG modeling development

OAM Handler

L L LLLLLLL

A A A

PCE driven by OAM

SSSSSS

Link1 Link2

ADC+Processing

X

TxBVT Rx

Controller

PCCRSVP-TE RSVP-TE

Controller Controller

Local OAM Agent

ActiveStateful

PCE

QoT monitor

2 – PCUpd (LDPC rate adaptation + spectralexpansion)

3 –Path

8 –Resv

5 –filter shape(expand)

6 –Resv

7 –filter shape(expand)

9 –LDPC rate adaptation

10 – PCRpt

Pol-Mux

IQ-modulators

Configurable Electrical

Data generation

Tunable carrier comb

BVT Tx

oddch.

evench.

I Q

I Q Pol-Mux

couplers

USBUSBeth

eth

OOK Tx

OOK Rx

OAM Handler

4 –Path

OAM Handler <-> PCE interaction

• OAM Database instance ->Augmented TED / LSP-DB• OAM LSP-DB: <BER>, <coherent receiver variance>,< ……• OAM TED : <power><amp_gain><…

• Direct PCE<->OAM Handler interface needed?

PCE

OAM Handler

PCEP

TEDOAM TED

LSP-DBOAM

LSP-DB

NETCONF

R

R only(OAM-aware path computation)

R/W

OAM InstanceMain Instance

1) Through ABNO controller2) PCEP (OAM:PCC)3) Dedicated protocol4) Internal API (if co-located)

Conclusions

• Proactive PCE – Fast reaction in presence of network degradations– Computation and dynamic update of additional parameters

• Presented use case– Hitless code rate adaptation in next generation transponders– Active PCE in charge of computing the most suitable

adaptation– Advanced monitoring functions

• ABNO boxes interaction– Close relationship between OAM Handler and PCE– Proposed Hierarchical OAM infrastructure with

NETCONF– Dedicated database extensions/sessions populated by

OAM– Shared handling of the ABNO database sessions

Thank you

• Francesco Paolucci, Scuola Superiore Sant’Anna

• fr.paolucci@sssup.it

ACKNOWLEDGMENTS-collaboration with IDEALIST project

Questions are welcome