Interface to the Routing System

1
Interface to the Routing System

• Adrian Farrel
• adrian_at_olddog.co.uk
• afarrel_at_juniper.net

2
Agenda

• What is the Routing System?
• What do we want to do with the Routing System?
• What tools already exist?
• An architecture for IRS
• Requirements for IRS
• IRS Work to be done
• Integrating the toolkit

3
The Routing System

• The forwarding plane is just part of a router
• We are interested in larger granularity impact

Router
Topology DB
Config
Config DB
RIB
Routing and Signalling
RIB Manager
Policy DB
Data Plane
FIB
OpenFlow
3
4
Advanced SDN Use Cases

• Programming the Routing Information Base
• For example, adding static routes
• Setting routing policy
• Control how the FIB is built
• Other router policies
• Modify BGP import/export policies
• Topology extraction
• Pull routing information (including SRLGs) from
  network
• Topology management
• Create virtual links by making connections in
  lower layers
• Service management
• Request LSPs, connections, pseudowires
• Bandwidth scheduling
• Set up a VPN

5
Existing SDN Tools - OpenFlow

• Useful, programmatic remote API
• Initially targeted at data / forwarding plane
• Separation of control plane from data plane
• RAPI nature introduces extensibility issues
• New revisions not backward compatible
• Hard to add new data models
• Current version has some concerns
• Synchronous completion is assumed
• No support for bidirectional flow
• Security model is not complete
• Use needs coordination
• A routing protocol
• An orchestrator

6
Existing Tools - ForCES

• IETF protocol and encoding language
• An open standard
• Separation of control and forwarding planes
• Originally developed to support COTS
• Standard, but in-box protocol
• Use rapidly extended to out-of-box
• Has been used to model OpenFlow
• Provides the same level of function
• Use needs coordination
• A routing protocol
• An orchestrator

7
Existing Tools - Config

• All routers have configuration interfaces
• Command Line Interface
• Non-standard
• Varies from one product release to the next
• Easy to script
• Hard to parse output ("screen scraping")
• All config approaches tend to be batched
• Enter many config commands
• Verify the config
• Commit
• So config is slow and complicated

8
Existing Tools - Netconf / YANG

• IETF standardised protocol and encoding language
• Netconf
• Next generation configuration protocol
• Lessons learnt from SNMP
• Reduced "chattines" of protocol
• Multiple objects set at once
• Security is far simpler
• YANG
• XML-like encoding language
• Easy to define new data models
• Not yet widely adopted
• Usage currently has many of the disadvantages of
  config

9
Existing Tools - PCE

• Initially conceived as a path computation server
• Solving the problem of inter-AS MPLS-TE
• Stateless computation
• Uses Traffic Engineering Database
• Extended for stateful computation
• Recalls information about previous computations
• Learns state of provisioning from network
• New extensions for "Active PCE"
• PCE can issue provisioning commands
• Enables new services
• Topology creation
• Scheduled services
• Dynamic re-optimisation and grooming

10
Existing Tools - BGP-LS

• How does a PCE obtain the TED?
• Unspecified in the architecture
• Early implementations participate in IGP
• Updates may be too frequent
• Implementations must support IS-IS and OSPF
• Most TE networks have a BGP-capable router
• BGP nodes are designed to process routing
  policies
• BGP-LS is set of simple extensions to advertise
  topology info
• Speaker
• Possibly a Route Reflector
• Uses policy to determine what to advertise and
  when
• Consumer (i.e. PCE)
• Very lightweight BGP implementation
• Not drowned by network updates

11
Existing Tools - VNTM

• Virtual link is tunnel provided by link in lower
  layer (e.g., virtual MPLS-TE link made by optical
  circuit)
• Virtual topology is nodes, links, and virtual
  links
• Virtual Network Topology Manager
• An architectural component
• Responsible for coordinating between layers
• Integrates between PCEs at different layers
• Applies policies to create on-demand topology

12
Additional SDN Function
Network Application

• Applications need to dynamically
• Augment routing, based on
• Policy
• Flow and application awareness
• Time and external changes
• With knowledge of
• Topology (active potential)
• Network events
• Traffic measurement
• Etc.

Feedback Loop Control Information
13
New Tools Interface to the Routing System

• Data models for routing and signaling state
• RIB Layer unicast RIBs, multicast RIBs, MPLS
  LFIB, etc.
• Protocols ISIS, OSPF, BGP, RSVP-TE, LDP, PIM,
  mLDP, etc.
• Related Function policy-based routing, QoS, OAM,
  security, etc.
• Framework for integrating external data into
  routing
• Indirection, policy, loop-detection
• Filtered events for triggers, verification, and
  learning about changes to router state
• Data models for state
• Topology model, interface, measurements, etc.
• Device-level and network-level interfaces and
  protocols

14
The IRS Architecture
Application
Application
Application
Server
IRS Client
IRS Protocol Data Encoding
IRS Client
Router
OAM, Events and Measurement
Topology DB
IRS Agent
Routing and Signaling Protocols
RIBs and RIB Manager
Policy DB
Data Plane
FIB
15
IRS Requirements

• Programmability
• Easy to write an API
• Stateless communications (RESTful)
• Reduced session state
• No state retention between messages
• High throughput and highly responsive
• Does not require configuration to be reprocessed
• Multiple simultaneous asynchronous operations
• Multi-channel (readers/writers)
• Duplex communication
• Asynchronous, filtered events
• Topology information (IGP, BGP, VPN,
  active/potential)
• Easy encoding of data
• Parsable
• Extensible
• Standardised

16
IRS Work in Progress in the IETF

• Nine Internet-Drafts for IRS
• IETF-85 Atlanta, Georgia, 3-9 November 2012
• IRS Birds of a Feather (BoF)
• Establish architectural view
• Investigate use cases and requirements
• Determine level of support to do real work
• Form an IETF Working Group
• Need to select the key use cases
• Agree a charter
• Appoint chairs
• Target date early 2013
• Rename to stop frightening the Cousins
• I2RS

17
IRS Working Group - Scope and Work

• Architecture
• Requirements
• Details of selected use cases
• Information models for use cases
• Analysis of existing tools and protocols
• Re-Charter required before further work
• Work on protocols (extensions or new protocols)
• Select or invent encoding language
• Develop data models
• Join the discussions and contribute to the work
• http//www.ietf.org/mailman/irs-discuss

18
Integrating the Toolkit

• Re-use of tools is efficient and timely
• Leverage existing developments
• SDN problem space demands many functions
• Make use of all the tools in the toolkit
• Build new tools to fill the gaps
• Application-Based Network Operation (ABNO)
• An SDN Toolbox Architecture
• Facilitate high-function network operation
• Integrate all of the existing features
• Create a framework for IRS

19
Application-Based Network Operation

• SDN tools provide high-function, but low
  granularity
• There is a need to coordinate SDN operation to
  provide service-level features
• Some components already exist or are proposed
• Orchestrators
• OpenFlow Controllers
• Routing protocols
• Config daemons
• IRS Client
• Virtual Network Topology Manager
• Need a wider architecture to pull the tools
  together
• A framework in which the SDN components operate

20
ABNO Framework
NMS/OSS
Application/Service Requester
ABNO Controller
IRS Agent
Virtual Network Topology Manager
IRS/PCEP
Network Policy
Off-Board Routing Protocol
PCE
Resource Manager
TED
PCEP
OpenFlow/Forces
BGP-LS
Network
IRS
Config/Netconf
Routers
OpenFlow/Forces
21
Toolbox Example Virtual Topology

• Cannot address a service request in IP/MPLS
  network
• Create a connection in an under-lying optical
  network
• Make a virtual link to enable the service

Traffic demand Service request
BGP-LS
PCEP
IGP-TE
PCEP
IRS
Virtual Link
RSVP-TE
Policy
OpenFlow ForCES
IRS
PCEP
GMPLS
IRS
IGP-TE
22
Summary

• Basic SDN function available today
• OpenFlow, ForCES
• Existing tools for advanced SDN function
• PCE, BGP-LS, VNTM, Netconf
• Advanced SDN function
• Programmable access to core router function
• Available as the Interface to the Routing System
  (IRS)
• Integration of the toolkit
• Chiefly and architectural task
• Application-Based Network Operation (ABNO)

23

• Questions?
• adrian_at_olddog.co.uk
• afarrel_at_juniper.net