This document discusses bringing SDN principles to network management planes at scale. It outlines challenges of managing large networks including multiple vendors, high configuration changes, and lack of visibility. It proposes applying SDN concepts like centralized control, network abstractions, and standard protocols. The document advocates for model-driven network management using standardized configuration and telemetry models like OpenConfig, which is an industry collaboration to define vendor-neutral models. It describes an intent-based configuration flow using these models and streaming telemetry for network visibility.

1. Bringing SDN to the
Management Plane (@scale)
Anees Shaikh
Google Technical Infrastructure

2. Management plane challenges
Programmability in the management plane
OpenConfig -- community-driven development3
2
1
Agenda

3. Google backbone networks
70+ edge PoPs in 33 countries
connecting Internet-scale
data centers around the world
traffic serving for
● hundreds of millions of hours viewed per day
● 300 hours of video uploaded per minute

4. Management plane challenges

5. Challenges of managing a network@scale
● 20+ network device roles
● 4M lines of configuration files
● more than half dozen vendors, multiple platforms
● up to ~30K configuration changes per month
● many tools, and multiple generations of software
Opportunity for significant OPEX savings: reduced outage
impact, simplification of management stack, better scaling

6. Management plane is way behind
● proprietary CLIs, lots of scripts
● imperative, incremental configuration
● lack of abstractions
● configuration scraping from devices
● SNMP monitoring -- not “simple”

7. Lack of visibility leads to inefficiency
● SNMP is our de-facto monitoring mechanism but poorly suited
○ legacy implementations -- poor performance and scaling
○ rigid structure -- limited extensibility to add new data
○ proprietary data -- require vendor-specific tooling
● Efficient traffic management requires tight control loops, and
real-time visibility

8. Toward a programmable
management plane

9. SDN applied to configuration management
SDN principle Applied to configuration
separation of control
and data
authoritative configuration outside of devices;
scraped config is not authoritative !
centralized control
network-wide, coordinated, configuration and
visibility
network abstractions
and APIs
knowledge in data models, pub/sub API for
obtaining network state
standard protocols and
interop
adoption of standard configuration data models is
crucial to enable vendor-neutral configuration

10. Configuration
• describes configuration
data structure and content
• common modeling
language: YANG
• multiple data encodings:
protobuf, XML, JSON, ...
Topology
• describes structure of the
network
• common modeling
language: ?
• data encoding: protobuf, ...
Telemetry
• describes monitoring data
structure and attributes
• common modeling
language: exploring YANG
• data encoding: JSON, ...
Model-driven network management

11. Intent-based configuration flow
abstract configuration models
Config
Model
Topology
Model
configuration intent
operators
declarative API
configurationflow
configuration pusher
NETCONF, RESTCONF, JSON-RPC, ...
...
authoritative
config store
config
generation
device-level configuration
standard
models
vendor-neutral configuration models
generated
configuration instances
config
generation
authoritative
config storeapplication
NB APIs
Network OS
SB protocols
SDN stack

12. Streaming telemetry
network state changes observed by analyzing comprehensive time-series data stream
● devices programmed with a
data model describing
desired structure and
content
● stream data continuously --
with incremental updates
● support for efficient, secure
transport protocols

13. OpenConfig

14. OpenConfig
● Informal industry collaboration of network operators
● Focus: define vendor-neutral configuration and operational
state models based on real usage
○ Adopted YANG data modeling language (RFC 6020)
● Participants: Google, BT, AT&T, Microsoft, Cox, Facebook,
Level3, Verizon, Comcast
● Primary output is model code, published as open source via
public github repo
● Ongoing interactions with standards community (e.g., IETF,
ODL)

15. “The fact that these
distinctly different -- and
often competitive -- service
providers are working
together is an indication of
the urgency they feel ...”
LightReading, “The New IP”, 11/24/2014
“Collaboration innovation”
“Instead of waiting for
standards, operators are
pushing them forward and
showing a willingness to
move on their own as well,
when it is in their best
interests”

16. INTERNAL: Google Confidential and Proprietary
Extending OpenConfig models
● base OpenConfig model as a starting point
● vendors can offer augmentations / deviations
● operators can add locally consumed modifications
base model
X vendor modifications
local modifications
extended model

17. INTERNAL: Google Confidential and Proprietary
Models must be composed to be useful
● model composition framework is
critical missing piece from existing
model-building efforts

18. Example configuration pipeline with
OpenConfig models
configuration
instance data
(protobuf / YAML)
validation I
validated
configuration
(proto / YAML)
encode for
transport to
devices (XML,
JSON, proto)
r/w to
native
config
device vendors
18
OC
YANG
models
configuration
generation
validation II
topology, policies,
constraints
OC
to/from
native
model

19. OpenConfig progress
● BGP and routing policy models published
● MPLS / TE model in progress
● device meta-model in progress
● interfaces, system, IS-IS, L3VPN, …
● native implementation discussions with several major vendors

20. Summary
● Time for the management plane to join the age of SDN
● Core principles: configuration and topology models; declarative
configuration; streaming telemetry
● OpenConfig is a focused effort by operators to drive model
development based on operational use cases
Invitation to additional network operators in all sectors:
leverage OpenConfig to enable your networks with a
programmable management plane

21. Thank you

22. Google global CDN