From GMPLS to OpenFlow Control & Monitoring of Optical Networks, Piero Castoldi. Acknowledgements (people): A.Giorgetti, F. Cugini, F. Paolucci, B. Martini, N. Sambo, M. Gharbauoi, A. Sgambelluri, D. Adami. Workshop “(G)MPLS and OpenFlow: Interworking, Integrating, or Replacing?” Dublin, May 7 2013

1. From GMPLS to OpenFlow Control&Monitoring
of Optical Networks
Piero Castoldi
Acknowledgements (people):
A.Giorgetti, F. Cugini, F. Paolucci, B. Martini, N. Sambo, M. Gharbauoi, A. Sgambelluri,
D. Adami
Acknowledgements (projects): STRONGEST, IDEALIST, OFELIA
Workshop “(G)MPLS and OpenFlow:
Interworking, Integrating, or Replacing?”
Dublin, May 7 2013

2. Outline
• Introduction on optical network management and
control
• Emergence of Software Defined Networks
• A couple of specific implementations for flexible
optical networks
– Control of Optical Network through OpenFlow
– Monitoring Experiments of Optical Networks through
OpenFlow
© 2013 Scuola Superiore Sant’Anna

3. There was the centralized management of ON ..
Static NMS
1
• Management plane: coordination of network
elements to configure, analyze and monitor
network resources to guarantee network
operation
“FCAPS” functions
– Fault management: detecting failures and isolating
failed component
– Configuration management: managing orderly
network changes e.g. equipment addition/removal
– Accounting management: billing and developing
component lifetime histories
– Performance management: monitoring and
managing various network performance metrics
– Security management: user authentication, control
access to network elements, user data protection
etc.
© 2013 Scuola Superiore Sant’Anna

4. From centralized to distributed GMPLS network
control ..
2
Static NMS
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
– Path computation
– Connection establishment
and release
– Fault recovery
1
•
• GMPLS CP aimed at
enforcing automated
connection management
Routing
– Open Shortest Path First with Traffic Engineering extensions, OSPF-TE
•
Signaling
– Resource Reservation Protocol with Traffic Engineering extensions, RSVP-TE
•
Link Management
– Link Management Protocol LMP
•
Path Computation
– Distributed: locally performed at the source node that receives the connection
request
© 2013 Scuola Superiore Sant’Anna

5. Some functions returned centralized ..
PCE
2
Static NMS
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
1
3
•
Path Computation
– Centralized: performed in a Path Computation Element communicating with the
connection source node using the Path Computation Element Protocol (PCEP)
•
PCE maintains a TED
– Updated by means of the LSA flooded by the running OSPF-TE routing protocol
– Updated by means of direct communication with the network nodes
•
Stateful PCE
– Besides the TED, also information about the previously computed path are utilized
during path computation
•
Stateless PCE
– Only the information stored in the TED are used for path computation
© 2013 Scuola Superiore Sant’Anna

6. Impairment awareness in GMPLS CP
GMPLS lightweight extensions to RSVP-TE signaling protocol
encompass physical impairment awareness degradation in alloptical networks:
• Encompassing an OSNR model that accounts for physical
attenuation, Polarization Mode Dispersion (PMD), Chromatic
Dispersion (CD) and Self Phase Modulation (SPM), to identify the
best wavelength assignment.
• Encompassing crosstalk effect via the Crosstalk Vector (XV)
object to identify the preferred wavelengths, e.g. the ones with
minimum added crosstalk.
• Encompassing the use of shared regenerators thanks in a
distributed way (object accounting for already used regenerators
and explicit flag for regeneration)
© 2013 Scuola Superiore Sant’Anna

7. Emergence of Software Defined Networks
© 2013 Scuola Superiore Sant’Anna 7

8. Software Defined Networking
Network Services
APP2
APP1
(e.g., Access
Control)
(e.g.,Protected
path)
APP3
(e.g., network
defrag)
•
Software Defined Network
Controller(s) (e.g. NOX)
NMS Adap
SNMP
OpenFlow
EM Intf
SNMP
OF Intf
NMS-based
network
GMPLSbased
network
OF-based
network
Legacy Network devices
•
•
•
Software-defined networking (SDN)
emerged as a new paradigm that
decouples physical network
implementation from network
control logic.
Data plane functions (forwarding)
reside within network elements
(switches, routers)
Control plane functions (routing,
signaling) are moved to a separate
dedicated controller
Network Services are realized
through dedicated APPlications
running within the Controller OS
Network
© 2013 Scuola Superiore Sant’Anna

9. OpenFlow is SDN but not viceversa
• OF is currently the suggested interface by ONF between
the controller and the OF-capable network device.
• OF is under consideration in several scenarios such as:
carrier grade Ethernet, and optical transport networks.
• The controller manages the
switching
elements
(i.e
OpenFlow
switches)
by
programming
their
flow
tables.
© 2013 Scuola Superiore Sant’Anna

10. The return of centralized control of optical networks
PCE
2
Static NMS
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
OF-GMPLS cooperation
OpenFlow controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
1
3
4
GMPLS replacement by OF
•
OpenFlow is being adapted for controlling optical networks
•
Key idea: OpenFlow controller perform path computation, node
configuration, lightpath maintenance and monitoring functions
through unique, open, standard protocol (OPEX reduction with
respect to distributed GMPLS suite)
•
E.g In flexible optical networks, additional parameters can be
considered for lightpath provisioning: modulation format, FEC,
type of channel, allocated spectrum, transponder/receiver
dynamic configuration
OpenFlow controller
5
© 2013 Scuola Superiore Sant’Anna

11. Network Facilities
at SSSA/CNIT
Pisa
SDN/OF controller (NOX, Flowvisor)
GMPLS control plane
Middleware (Ofelia control framework)
ROADM
Ericsson MHL3000
1 ch add-drop
@ 10Gb/s
DWDM
GMPLS
GE/FE
Data
Center
•
•
•
•
Juniper M7i/M10 routers
Juniper EX3200/2200 switches
Cisco 7200 VXR router
Emulated OpenFlow switch
GE/FE
OF controller
CNIT-Pisa
Ofelia island
OpenFlow
Ethernet
ring
© 2013 Scuola Superiore Sant’Anna

12. Control of Optical networks through OpenFlow
12
© 2013 Scuola Superiore Sant’Anna

13. OF-GMPLS lightpath setup (cooperation mode)
• Source: request to OpenFlow controller
• OpenFlow controller: routing
TED update: previously routed
requests
OpenFlow controller: reply to
source
• Source: RSVP-TE Path to destination
OpenFlow controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
GMPLS
controller
Explicit Route Object
Label Set Object
Suggested Label
• Destination: wavelength assignment
• Destination: RSVP-TE Resv to source
Resource reservation
OXC cross connections
• Lightpath established
© 2013 Scuola Superiore Sant’Anna

14. OF lightpath setup
(replacement mode)
•
•
OpenFlow controller
Source: request to OpenFlow
controller
OpenFlow controller: routing
TED updated: previously routed
requests
•
•
Controller: flow configuration at each
OXC
Each OXC: flow configuration
Resource reservation
•
OpenFlow controller: reply to source
Controller
Timer
OF-timer:
• Wait timer expiration without errors
OF-ack:
• Wait the last ack
•
Data
Lightpath established
© 2013 Scuola Superiore Sant’Anna

15. OF-based flexi lightpath provisioning:
OF-ACK scheme implementation
• Switch-controller OF session
over TCP
• Lightpath setup needs node
configuration confirmation
• Provisioning Request-Reply
maintained (PCEP-like)
• Fast parallel node configuration
• Errors handling: no-path, failed
flow_mod
OF Controller
Messages:
• lightpath_in (lightpath request)
• flow_mod (set flow entry)
• flow_ack (ack entry)
• lightpath_out (lightpath setup
outcome)
OU
H_
AT
TP
OFPT_FLOW_MOD
IGH T
OFPT_FLOW_MOD
T_L
OFPT_FLOW_MOD
FP
O
P
OF
T
IGH
T_L
TH
PA
_IN
© 2013 Scuola Superiore Sant’Anna

16. OpenFlow controller implementation
•
•
•
•
Based on the PCE engine, path_solver +
Controller_handler modules
Performs path computation: route, spectrum
assignment, modulation format and FEC
assignment, impairment validation. Different IV
and RSA strategies available (joint, IV+RSA)
Performs node configuration (centralized
signaling): Cross-connections, WSS spectrum
shaping, TX/RX fine configuration, flexible
submodules on/off
Performs monitoring (statistics collection and
analysis) and feedback-based optimization
Optical channel QoT parameters monitoring
Degraded QoT triggers analysis (fault localization
through cross-correlation) and decisions (e.g.,
lightpath re-routing, dynamic modulation format
adaptation)
Path
solver
OFTED
IV
models
Controller
Handler
OF interface
OF sessions
© 2013 Scuola Superiore Sant’Anna

17. OpenFlow Switch implementation
• Port configuration
(switch abstraction),
state and statistics
• Flow table stores
active entries (installed
flows)
• Device interface maps
configuration
commands into
hardware-specific
commands
Controller session
OF interface
Port
config,
state,
stats
OF switch
handler
Flow
table
Device interface
Switch
hardware
© 2013 Scuola Superiore Sant’Anna

18. Flexi Optical ROADM/Switch abstraction
•Design relies on different
port types (fixed or flexible,
IN_PORT [ ]
depending on the switch
architecture) and flexible
transponder/receiver
•Flow entry format:
transit
•Intermediate hop: [in_port
(transit), out_port (transit)
,assigned_ spectrum]
•Src: [in_port (add), out_port
(transit), assigned_spectrum,
add
OCh_spec]
•Dst:
[in_port
(transit),
out_port
(drop),
assigned_spectrum,
OCh_spec]
•Spectrum collision check
performed at each out_port
TX
OUT_PORT [ ]
transit
drop
RX
© 2013 Scuola Superiore Sant’Anna

19. Monitoring Experiments of Optical Networks
through OpenFlow
19
© 2013 Scuola Superiore Sant’Anna

20. Monitoring in OpenFlow-based networks
• OF-Controller responsible to compute and configure flow
tables (i.e., forwarding tables) on OpenFlow switches
• Statistics are typically exchanged for manageability and
monitoring functions. Symmetric messages
(OFPT_STATS_REQUEST and OFTP_STATS_REPLY)
• Port status info may be exchanged to notify link failures.
• New types of statistics are required in flexi-grid networks,
e.g.:
Quality of Transmission (QoT) statistics
OAM statistics
• OF-Controller may utilize statistics information to improve
monitoring, fault notification, localization, etc.
© 2013 Scuola Superiore Sant’Anna

21. Flexi optical network and monitoring enhancements
•BER and MSE statistics at coherent receiver (PM-16QAM, PM-QPSK)
•OSNR, non-linear parameters, frequency offsets, equalizer coefficients (CD
and PMD estimation)
© 2013 Scuola Superiore Sant’Anna

22. OpenFlow monitoring statistics
•
For each lightpath monitoring parameter, specific field within
OFPT_STATS_PORT_LP structure is defined and managed in
switches
•
OF-Controller performs periodic requests at configurable time
interval (DEFAULT_POLL_PORT_PERIOD, e.g. 1 min.)
Polling rate may change according to network conditions
•
•
OF-Controller enhanced with new IN_PATH vector storing also
statistics. Each activated lightpath (unique DPID) includes
IN_PATH including traversed links ->correlations among statistics
and actual traversed resources are possible
© 2013 Scuola Superiore Sant’Anna

23. Experimental demonstration (1)
BER statistics collected by OF-Controller
L1
L4
Warning BER threshold
Critical BER threshold
L2
L3
EDFA
• 4 lightpaths activated (L1-L4), 200Gb/s 16-QAM, coherent detection
• BER monitoring updated every 1 min.
• QoT degradation on link 3-4, time increasing
• Warning and Critical thresholds set at OF-Controller, polling rate raises to 1s
• Correlations : statistics and traversed link info stored within IN_PATH
-> Link 3-4 identified as possible degradation source
© 2013 Scuola Superiore Sant’Anna

24. Experimental demonstration 2
Capture of OpenFlow messages
Modified OpenFlow Stats Reply message
• Bit Error Rate (BER) field enclosing current BER measurement at port
PORT_NUMBER
• Further actions applied by OF-Controller upon new requests:
1. Stronger modulation format while maintaining bit-rate (QPSK, 200G)
2. 2 LSPs halving the bit-rate (QPSK, 100G)
3. Different route (e.g., 3-2-1 with respect to 3-4-1)
© 2013 Scuola Superiore Sant’Anna

25. Research directions and open points
• OF controller and switch implementation extensions
• Global re-optimization (e.g., OF-driven PushPull technique)
• Protection and fast restoration solutions
• Multicast (P2MP) support
• OF multi-domain, multi-layer
• SDN alternative or complementary to distributed GMPLS
for reliability?
• Recognized GMPLS advantage: efficient fast recovery
• Potential SDN drawbacks: scalability issues, controller
communication failure issues, complex disaster recovery
• Pure/mixed architectures to be considered and evaluated (e.g.,
pure OF, OF+ basic RSVP-TE, OF +RSVP-TE +LMP)
• OpenFlow controller and PCE: which relationship?
© 2013 Scuola Superiore Sant’Anna

26. Recent Related recent publications
•
•
•
A.Giorgetti, F. Cugini, F. Paolucci, P. Castoldi,
“OpenFlow and PCE architectures in Wavelength
Switched Optical Networks”, ONDM 2012
F. Paolucci, F. Cugini, N. Hussain, F. Fresi, L. Potì,
“OpenFlow-based Flexible Optical Networks with
Enhanced Monitoring Functionalities”, ECOC 2012
N. Sambo, F. Paolucci, F. Cugini, M. Secondini, L.
Potì, G. Berrettini, G. Meloni, F. Fresi, G. Bottari, P.
Castoldi, “Software Defined Code-rate-adaptive
Terabit/s based on time-frequency Packing”,
submitted to OFC/NFOEC 2013
© 2013 Scuola Superiore Sant’Anna

27. thank you!
E-mail:
castoldi@sssup.it
© 2013 Scuola Superiore Sant’Anna