Interface to the Routing System

January 7, 2018 | Author: Anonymous | Category: Engineering & Technology, Computer Science, Computer Networks
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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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