The Need for SDN in Orchestration of IP over Optical Multi-Vendor
Networks
Ori Gerstel, CTO, Sedona Systems
Victor Lopez, GCTO team, Telefonica
Acknowledgement: ACINO project, EU grant 645127
1-Oct-2015 1
Outline
• What is SDN? What is ML control about?
• When is central control necessary?
• Different forms of control distribution
• Experimental validation
What is SDN (in 1 slide)• A control architecture that is based on centralized
control instead of distributed control• Why?
• Simpler design/code than a distributed solution• Opportunity to commoditize the hardware• Open for 3rd party app development• More optimal global decisions
1-Oct-2015 3
CP CP CP
Distributed architecture (PMO) Centralized architecture
SDN
Data Data Data Data Data Data
What is SDN (more realistic definition)
• A control architecture that is based on some centralized control instead of fully distributed control
• Why?• Existing gear will live in the network for many years• Some functions are better implemented in distributed fashion• The risk of moving to a disruptive new architecture is too high
1-Oct-2015 4
Hybrid architecture
SDN
CP CP CPData Data Data
What does ML control enable?
• Streamlined operation
• Multi-layer restoration and optimization
• Multi-layer services
Multi-layer discovery and visibility
Always-accurate network view
Learn topology and traffic in each layer
Learn cross layer mapping
Cross-layer awareness
Reduced service downtime
Provision L3 links with optical SRLGs
Reroute optical connections to provide more diversity
Outline
• What is SDN? What is ML control about?
• When is central control necessary?
• Different forms of control distribution
• Experimental validation
Optical controller requirements
• Get topology, links & ports
• Get connections & their path
• Set up new connections with path constraints
• Define optical restoration properties for connections
• Push alarms
• Compute feasible paths (PCE)
http://sedonasys.com/what-multi-layer-control-requires-from-the-controllers-for-each-layer/
IP controller requirements• Get topology, links & ports• Get LSP, their path &
reserved/actual bandwidth• Get e2e IP traffic matrix• Push alarms• Simulate IP layer behavior under
link add/remove• Add IP link & configure its
properties• Cost out IP link
http://sedonasys.com/what-multi-layer-control-requires-from-the-controllers-for-each-layer/
What is ML control about?
Optical brain IP brainML brain
Network Network
Requires collection of a lot of global data+ heavy processing of the data+ lots of back and forth negotiation extremely complex in a distributed fashion= Central control
Does this mean distributed control is dead?
• No
• Distributed control is useful inside a vendor domain• Connection set up• Restoration
• Distributed control is useful between orchestrators of different Service Provides• East-West interface
Domain DomainDomain Domain
Orchestrator Orchestrator
Controller Controller Controller Controller
Does this mean distributed control is dead?
• NNI? Probably dead
• UNI? Useful for corner cases• IPoDWDM + restoration + WL change
Domain DomainDomain Domain
Orchestrator Orchestrator
Controller Controller Controller Controller
Outline
• What is SDN? What is ML control about?
• When is central control necessary?
• Different forms of control distribution
• Experimental validation
Different forms of control distribution (outline)
• Network control architecture
• Internal controller architecture
• Multi-layer/vendor architecture
1-Oct-2015 19
Hybrid control models(OFC’15)
1-Oct-2015 20
Initiation Policy decision
Path selection
Path setup
Distributed model
Central path compute model
Policy provisioning model
Centralized model
• Initiation: who decides to set up the path?
• Policy decision: who decides about the constraints for the path?
• Path selection: who decides how to route the path?
• Path setup: who configures the nodes along the path – and (typically) who restores it?
Hybrid control models(OFC’15)
1-Oct-2015 21
Initiation Policy decision
Path selection
Path setup
Distributed model D D D D
Central path compute model D D C [+D] D
Policy provisioning model C C D D
Centralized model C C C C
Hybrid control models(OFC’15)
• Setup initiated by the central controller
• It decides on the constraints and provisions the head-end with one or more policies
• The head-end computes the path based on the policies
• The path is set up via distributed signaling (RSVP)
• The network retains autonomous actions (e.g., restoration)
1-Oct-2015 22
Initiation Policy decision
Path selection
Path setup
Distributed model D D D D
Central path compute model D D C [+D] D
Policy provisioning model C C D D
Centralized model C C C C
R1 R3
O1
O2
O3
SDN
controller
3. GMPLS-UNI creates the
optical circuit leveraging
WSON
3
2. SDN controller triggers
creation of new link by
provisioning the router with
policies
2
Hybrid control example
1a
1. SDN controller learns
optical network from (a)
Optical layer, (b) IP layer
1b
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4. Upon failure GMPLS
acts according to the
policies
Hybrid distributed and centralized control – not our invention…
Centralized control
Distributed control
1-Oct-2015 24
Different forms of control distribution (outline)
• Network control architecture
• Internal controller architecture
• Multi-layer/vendor architecture
1-Oct-2015 25
Carrier grade requirements
• Typical carrier-grade req.s for the controller:1. It must survive HW/SW failures
2. It may have to keep working during SW upgrades
3. It may have to scale to a large number of transactions
• (Some of these req.s are not mandatory if the controller is not involvedin real-time operation)
Distributed systems address these req.s
• A failure of one copy does not affect other ones
• Upgrade of one copy allows other copies to continue working
• The workload can be distributed amongst multiple copies
Distributed systems address these req.s
• Typical solution: use distributed database to keep all copies in sync
• Note: this does not imply we’re back to complex distributed systems
Controller
Adapter
NE
Adapter
NE
Apps
Network DB
Controller
Adapter
NE
Adapter
NE
Apps
Controller
Adapter
NE
Adapter
NE
Apps
Controller
Adapter
NE
Adapter
NE
Apps
Distributed network DB
Different forms of control distribution (outline)
• Network control architecture
• Internal controller architecture
• Multi-layer/vendor architecture
1-Oct-2015 29
Monolithic SDN architecture
Monolithic SDN controller
ML App
30
• Monolithic approach: • Single controller controlling
multiple layers and vendors
• Concerns:• Complex to manage
• Complex to troubleshoot
• Complex to upgrade
• Recreating some of the issues SDN was meant to solve
1-Oct-2015
L3 NEsL0/1 NEs
Monolithic SDN architecture
Monolithic SDN controller
ML App
31
• More concerns:• Optical feasibility “must” be
computed by the optical vendor
• Simulation of IP layer behavior “must” be computed by a tool that understands its complexity
• No single vendor can provide all of this
1-Oct-2015
L3 NEsL0/1 NEs
Modular Hierarchical SDN architecture
Orchestrator
L3 SDN controller
L3 NEs
L0/1 SDN controller
L0/1 NEs
ML App
32
• Modular approach:• Specialized SDN controller for
each layer• Separate SDN orchestrator
which relies on single layer controllers for single layer services
• More open and flexible solution
• Leaves room for vendor expertise and innovation
1-Oct-2015
Modular Hierarchical SDN architecture
Orchestrator
L3 SDN controller
L3 NEs
Vendor 2 controller
Vendor 2 NEs
ML App
33
• In fact, in some layers (E.g., DWDM), a controller per vendoris likely• We have failed to
agree on a common way to model transmission impairments
1-Oct-2015
Vendor 1 controller
Vendor 1 NEs
Outline
• What is SDN? What is ML control about?
• When is central control necessary?
• Different forms of control distribution
• Experimental validation
Tu.1.6.5, SDN/NFV, ECOC 2015
Transport SDN/NFV architecture
35
Dat
ace
nte
r
OpenDayLight#1
OVS
…
Cloud Controller(Distributed Data-centers)
SDN IT and Network Orchestrator (SINO)
Multi-domain Network Hypervisor
…Customer #1
OpenDaylight
NFV Orchestrator
OpenDayLight VNF Manager
Customer #NFloodLight
ONOS VNF Manager…
ONOS#N
GMPLS Controller
Packet Core
Switches
GMPLS Controller
GMPLS Controller
Packet Transport Network
Active StatefulPCE
Multi-domain SDN Orchestrator
Optical Transport Network
Experimental demos at Telefonica’s lab
SDN Solutions showcase (S3), as part of ONS, Santa Clara, CA 5/2015
Experimental demos at Telefonica’s lab
SDN Solutions showcase (S3), as part of ONS, Santa Clara, CA 5/2015
Experimental demos at Telefonica’s lab
• Multi-domain provisioning (3/15)
• Multi-layer optimization (3/15)
• Discovery of cross-layer links (5/15)
• Multi-layer provisioning (10/15)
• Sharing L0 SRLGs with L3 (10/15)
• Coordinated maintenance (10/15)
Optical IP
Vendor X
This project is fundedby the European Union
ACINO: Application-Centric IP/Optical Network Orchestration
645127 – ACINO - H2020-ICT-2014-1
www.acino.eu
Application-aware transport layer
App specific requirements
Grooming layer
Application layer
Low bandwidth
Medium / High bandwidth
App-class requirements
Summary
• Both distributed and centralized control systems have valuable attributes for network control
• It is possible to keep some functions distributed while centralizing others
• Multi-vendor systems are likely to be more distributed to allow for vendor innovation
• Typical network control is likely to be hybrid for the above reasons