1. PCE – OAM Handler in ABNO:
a use case of code adaptation in flex grid networks
Francesco Paolucci
TeCIP, Scuola Superiore Sant’Anna,
Pisa, Italy
PACE Workshop on “New uses of Path Computation Elements”
Vilanova y la Geltru , Spain, June 16th 2014

2. 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

3. ABNO architecture Active Stateful PCE OAM Handler Databases
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
Application-Based Network Operation (ABNO) framework.
“A PCE-based Architecture for Application-based Network Operations”
draft-farrkingel-pce-abno-architecture

4. PCE in Flexible optical networks
Next flexible transponders will support multiple configurable signal 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

5. Chain Example: Shift & Expand
PCReq (LSP 1: Elastic bit rate increase) 1 2
PCUpd (LSP 2: Shift) 3
LSP 2 shift 4
PCRpt (LSP 2: Shift OK) 5
PCRep (LSP 1: Elastic increase) 6
LSP 1 elastic increase 7
PCNtf (LSP 1: Elastic incresae OK)
LSP 2
LSP 1
Frequency 1
PCReq message
PCUpd message 2 3
RSVP make before break
PCRpt message 4 5
PCRep message 6
RSVP elastic increase 7
PCNtf message

6. 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 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

7. 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

8. Validation Testbed (PCEP+RSVP)

9. 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

10. 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

11. 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 A A A L L L L L L L L L

12. PCE driven by OAM

13. PCE OAM Handler 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? R
PCE
PCEP
Main Instance
OAM Instance
R only
(OAM-aware
path computation)
1) Through ABNO controller
2) PCEP (OAM:PCC)
3) Dedicated protocol
4) Internal API (if co-located)
TED
OAM TED
OAM Handler
NETCONF
LSP-DB
OAM LSP-DB
R/W

14. Conclusions Proactive PCE Presented use case ABNO boxes interaction
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

15. Thank you Francesco Paolucci, Scuola Superiore Sant’Anna
ACKNOWLEDGMENTS
-collaboration with IDEALIST project
Questions are welcome