Interface to the Routing System
Adrian Farrel
[email protected] [email protected]
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 2 of 23
The Routing System • The forwarding plane is just part of a router • We are interested in larger granularity impact Router Topology DB
Config
OAM, Events Measurement
Config DB RIB
Policy DB OpenFlow
RIB Manager
FIB
Routing and Signalling
Data Plane 3
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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” 4 of 23
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
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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 6 of 23
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 7 of 23
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 8 of 23
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 9 of 23
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 10 of 23
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 11 of 23
Additional SDN Function • Applications need to dynamically: – Augment routing, based on: • Policy • Flow and application awareness • Time and external changes
Network Application IRS
IRS
IRS
IRS IRS
– With knowledge of: • • • •
Topology (active & potential) Network events Traffic measurement Etc. 12 of 23
Feedback Loop: Control & Information
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 13 of 23
The IRS Architecture Application
Application Application
Server IRS Client
IRS Client
IRS Protocol & Data Encoding
Router OAM, Events and Measurement
Policy DB Data Plane
IRS Agent
RIBs and RIB Manager
Topology DB
Routing and Signaling Protocols
FIB 14
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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 15 of 23
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
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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 17 of 23
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 18 of 23
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
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ABNO Framework NMS/OSS
Application/Service Requester
ABNO Controller
IRS Agent IRS/PCEP
Network Policy
OffBoard Routing Protocol
Virtual Network Topology Manager
PCE
Resource Manager
TED
OpenFlow/Forces
PCEP
BGP-LS Network
IRS Config/ Netconf OpenFlow/ Forces
Routers 20 of 23
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
ABNO Controller TEDB
PCEP
IGP-TE
PCE PCEP IRS Policy
IRS
Virtual Link
RSVP-TE
VNTM
OpenFlow & ForCES
PCEP IRS
GMPLS PCE TEDB
IGP-TE 21 of 23
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) 22 of 23
Questions?
[email protected] [email protected]
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