Various Alternatives to achieve SDN

Dhruv Dhody, Sr. System Architect, Huawei Technologies

Who?H

uaw

ei • A multinational networking and telecommunications equipment and services company headquartered in Shenzhen.

• We are the largest telecommunications equipment maker in the world.

• Over 140,000 employees and 21 R&D institutes.

Ind

ia R

&D

• First and biggest R&D center outside of China.

• High end communication software platforms/components/ applications.

• Over 2600 engineers.

Dh

ruv

Dh

od

y • 11+ years in Huawei (Bangalore, Beijing, Santa Clara)

• Network OS dept with specialization in Traffic Engineering and Path Computation

• Lead a Research, Standards & Prototypes team

• 3 RFC / 8 WG documents / 13 Patents

SDN, Lets Recap!

Why SDN?Computing Trends are Driving Network Change

Changing traffic patterns

The “consumerization

of IT” (BYOD)

The rise of cloud services

“Big data” means more bandwidth

Complexity that leads to stasis

•Add/Move devices

• Implementing network wide policy

•Time consuming & Manual

•Prone to errors

Inability to scale

•Link oversubscription to provision scalability

Vendor dependence

•Lengthy vendor equipment product cycles

•Lack of standard, open interfaces

Limitation of Current Networks

Software-defined networking (SDN)

is an approach to computer

networking that allows network

administrators to manage network

services through abstraction of

lower-level functionality.

SDN - Definition

The physical separation of the network control plane from the forwarding plane, and where a

control plane controls several devices.

Directly programmable:

Network control is directly

programmable because it is

decoupled from forwarding functions.

Agile: Abstracting control from

forwarding lets administrators

dynamically adjust network-wide traffic flow to

meet changing needs.

Centrally managed: Network

intelligence is (logically)

centralized in software-based SDN controllers that maintain a

global view of the network.

Programmatically configured: SDN

lets network managers configure,

manage, secure, and optimize

network resources very quickly via

dynamic, automated SDN

programs.

Open standards-based and vendor-

neutral: When implemented through open

standards, SDN simplifies network

design and operation because

instructions are provided by SDN

controllers instead of multiple,

vendor-specific devices and protocols.

Dynamic

Manageable

Cost Effective

Adaptable

SDN @ ONF• Programmatically

communicate via NBI

SDN Applications

• Abstract view of network

• Controlling SDN Datapaths

SDN Controller

• Network Device

SDN Datapath

• Programmatic Control

• Capability and reporting

• Events

SDN CDPI

• Provide abstract network views

• Direct expression of network behavior (intent)

SDN NBIs

Multi-Layer SDN

SDN's logically centralized network intelligence and ability to leverage

cloud computing for almost unlimited compute power enables

it to evaluate all layers of the network concurrently to determine

where best to send traffic..

Today, a service is typically transported at a single layer. With

multi-layer SDN, a network can transport services over the most efficient technology, not just the predefined transport technology.

Ex. If bandwidth at a particular layer is exhausted in some portion of the

network, multi-layer SDN can evaluate options and dynamically add bandwidth from a lower layer or reroute traffic from upper layers

around the point of congestion.

E2E SDNOrchestration of E2E service delivery across all network domains

Distributed control planes with multiple cooperating controllers

• ƒƒ EWBI (east-west) for controller to controller communications across domains

•Enhanced SBI for support of specific network technologies and types

•Enhanced NBI for support of customer/network applications

Network virtualization and control capability

Cross layer coordination (e.g., IP routing + Optical Transport)

SDN – Alternatives (looking beyond OpenFlow)

PCE ALTO I2RS ACTN SR

PCE – Path Computation Element

PCE is an entity that is capable of computing a network path or route based on a network graph and applying computational constraints

Specializes in complex path computation across various domains on behalf of its path computation client (PCC) with enhanced scalability.

Stateless PCE provides mechanisms to perform path computations in response to PCC requests.

•It utilize only the TE link information database to do this computation (TEDB).

Stateful PCE: Along with network state (TEDB), it also stores the state of all the computed paths or LSPs and their resources (LSPDB).

•Enhanced algorithms at stateful PCE

PCE-Initiated: Setup, maintenance and teardown of PCE-initiated LSPs from a central PCE server.

Stateful PCE

Stateful PCE as evolutionary approach to SDN.

In SP network with existing investment in IP/MPLS devices, active stateful PCE can

offer centralized control over the LSPs as a simple evolutionary approach for SDN.

PCC

PCEP

Protocol

PCC

Stateful PCE Server

Abstraction & Algorithms over Stateful PCE

Stateful PCEOF-Based

SDNStateful

PCE

PCE capable to compute, initiate, control and

maintain the LSP.

PCE Server acts as the SDN controller.

Continue to use existing signaling mechanism (RSVP) or use segment routing (SR)

Only software update for edge router (PCC).

Controlling devices using a central orchestrator

Opens up the control of data flows to customizable

software.

New hardware might be needed

New protocol - OF

ALTO – Application-Layer Traffic Optimization

Protocol provides simple mechanism to provide basic,

abstract but useful network

information to applications.

Application can make use of this

information to use network efficiently.

This protocol developed on top of existing HTTP (REST-ful) using

JSON

Usecases

•Peer to Peer File sharing

•CDN

•Real-time Communication

•Live media streaming

Extension to ALTO are

proposed for

Abstract network

topology graph

Traffic Engineering

Service aware parameters

Calendering

…

•Net-Arbiter uses stateful PCE to query and obtain the network status

PCE

•Initially for P2P file sharing (torrents) & CDN to get simple network cost map

•HTTP/Restful/JSON

•ALTO extensions to support DC and network costs and events

ALTO •Joint optimized DC application resources along with network resources.

• DC Migration, Schedule Backup, DC & Network Events

CSO

DC 1DC 2

DC 3DC 4 DC 5

Application Stratum

Network Stratum

Arbitration Layer

APP Arbiter

NET Arbiter + PCE

ALTO

PCE+ALTO for Data Centre Interconnect

PCEP

Cross Stratum Optimization (CSO) -Optimization of Datacenter and Network resources - which can only be achieved via joint effort & information exchange - to cross optimize between stratums.

•Application DC resources Optimization

•Network resource Optimization

Abstract GraphApplication Controller

Network Controller

HYD(User region)

DLI(Data Center) BLR

BOM

Abstract Topology

Ab

stra

cte

d g

rap

h

Access to an Abstract network topology, could allow an Application to understand network in a much better way – find bottleneck, make dynamic decision with network conditions in mind…

I2RS: Interface to Routing System

•Switch programming (cross-connects)

•Forwarding (FIB)

SDN focuses on programming the data plane

•Control of routers

•Control of routing protocols

•Management of the “routing system”

There are many functions and features not covered

•Using CLI to achieve these functions is very frustrating

•Expensive, time-consuming, error-prone, risky

Existing techniques are non-standard

•Strong desire for a simple and standard approach

Need for a standard approach

I2RS

Usecasesfor I2RS

Programming and managing the RIB

BGP use cases

Traffic steering and classification

DDoS mitigation

Topology reading, monitoring, and control

Service chaining

I2RS to use Netconf/Restconf/Yang as the

base…

Netconf / Restconf / Yang

Netconf

• Network Management Protocol

• Remote primitives to view/manipulate data

• Encoding data as per the data model

• Think SNMP

• Transaction based (network wide)

Yang

• Data Model

• Explicit precise structure, syntax and semantics of the (externally visible) data

• Think MIB

• Configuration data as well as state

• Also events

Restconf

• A REST protocol over HTTP

• accessing data defined in YANG using datastores defined in NETCONF.

Netconf/Restconf/Yang as a base to manipulate state on the

device!! (I2RS)

ACTN - Abstraction & Control of Transport Networks• Multi-layered multi-domain Network

• Technology, administrative or vendor islands

• Interoperability for dealing with different domains is a perpetual problem for operators.

• New service introduction with connections that traverse multiple domains

• Need significant planning• Manual operations to interface different vendor equipment and technology

across IP and Optical layers.

• Facilitate virtual network operations • Creation of a virtualized environment allowing operators to view and control

multi-subnet multi-technology networks into a single virtualized network.

• Accelerate rapid service deployment of new services• including more dynamic and elastic services• improve overall network operations and scaling of existing services.

• Hierarchy of controllers

ACTNCustomer B

Control

Multi Domain Service Coordinator

Customer CControl

Customer AControl

41

2

5

6

51

2

5

6

11

2

3

45 6

3 4

3 4

7 8

A.1

A.2

A.3

B.1 B.2

B.3

C.2 C.3

21

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4

5 6

31

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5 6

PNC

Creates abstraction topology perapplication/client need

416

52

11 3

6

4

38

A.1

A.2

A.3

2145

323

6

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Multi-domain network topology

PNC

Physical Network Control like PCE

Segment Routing (SR)Simplicity - Less

numbers of protocols and interactions and automated FRR for

any topology

Scale - Avoid thousands of labels and TE LSPs in the

network

Leverage all services supported over MPLS today (L3/L2 VPN, TE,

IPv6)

Bring the network closer to the applications

Segment Routing

• the source chooses a path and encodes it in the packet header as an ordered list of segments

Segment

• an identifier for any type of instruction

• Service

• Context

• Locator

• …

• Distributed by IGP

How

• MPLS

• Label Stack

• IPv6

• List of segment in routing extension header

Applications

• Through PCE get optimized path

• Applications can interact and make changes through PCE

• Only the ingress needs to change the segment-list!

SR & SDN

SR supports a simple but efficient capacity planning

process based on centralized optimization

SR optimizes network resources by providing a very

simple support for ECMP-based shortest-path flows

SR provides much better scaling

SR provides guaranteed-FRR for any topology

SR provides ultimate virtualization as the network

does not contain any application state. The state is in the packet. It is encoded as

a list of segments

SR provides very frequent transaction-based

application as the network does not hold any state for

the SR-encoded flows

Application aware routing using SR

Conclusion…

There is more than one way to look at

SDN..

SDN in Enterprise and Datacenter is

different from SDN in carriers network

Re-using existing building blocks

need to be looked into…

•Retain some of the investment made in current network•As well as leverage benefit of SDN

•PCE, BGP, Netconf, Yang, ALTO…•Most Vendor companies are exploring these options….

Inline with ODL architecture…

Support Multiple Southbound/Data-Plane Elements

OpenFlow, NetConf, SNMP, BGP-LS, PCEP, LISP etc

Support IETF protocols to control physical and virtual routers and switches

• Border Gateway Protocol – Link State (BGP-LS)

• Path Computation Element Protocol (PCEP)

Thank You!