SDN: an introduction

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Customer Driven Innovation

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Do not distribute/edit/copy without the written consent of A10 Networks

SDN: an Introduction

Luca [email protected]

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Who am I

Luca Profico

RSE@a10networks

A10 Networks Networking company based in San Jose (CA) 10 years developing its own solutions 3# worldwide marketshare in ADC Market; #1 in Japan Leader in CGN and IPv6 Migration solutions

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Software-defined Networking

• SDN concept has been around for almost 9 years now but the concept is not yet clear

• Marketing is riding SDN with bigger and bigger promises

• What will we do with SDN?

• US ICT Event survey:• SDN, I don’t understand it but I want it.• All this fuss for old concepts remixed.• Will I lose my job because of SDN?

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What is, What is Not

SDN is not a protocol

SDN is not a suite of protocols

SDN is not a technology

SDN is a concept, a methodology, an architecture that aims at making network implementation, scalability and management easier by separating planes

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Network Devices and Planes

Build and exchange information

ARP MAC Learning STP …

Routing protocols Neighbors …

Build and store local L2/L3 info tables

Packet processing/forwarding decisions

Forwarding table

Controlplane

Dataplane

fwd tbl

p1

p3

p2

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Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Network Devices and Planes

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Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Network Devices and Planes

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Dataplane

fwd tbl

Dataplane

fwd tbl

Dataplane

fwd tbl

Dataplane

fwd tbl

Controlplane

Dataplane

fwd tbl

Dataplane vendor B

fwd tbl

Dataplane vendor C

fwd tbl

Network Devices and Planes

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Network

Network operating system

Middleware

vSwitchSwitch Switch Switch Switch vSwitch vSwitch

SDN Controller

Network Application

Network Application

Network Application

Network Application

Northbound API

Southbound API

SDN Implementation

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Open Networking Foundation

Members-only organization

Milestones Founded in 2011 More than 50 members in 1st yr. Over 100 members in 2013 (Vendors, SPs, Telcos)

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OpenFlow

Standard communication interface between control and forwarding layer

OpenFlow specs OF Switch specs 1.3.2 published 2013 OF Switch specs 1.4 approved 2013 OF-Config (conf & mgmt protocol) 1.1.1 published 2013

Simple traffic processing Flow tables Pipeline concept OpenFlow Switches Hybrid OpenFlow Switches

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OpenFlow Tables

Flow Table

Group Table

Meter Table

Match fields Priority Counters Instructions Timeout Cookie

Group Identifier Group Type Counters Action Buckets

Meter Identifier Meter Bands Counters

MAC src MAC dst IP src IP dst TCP dport … Action Count

* 10:20:. * * * * Port 1 99

* * 217.99.* * * * Table 6 18

* .:38:aa:. * * * * drop 4

* * * 7.7.9.4 25 * drop 172

* * * * 69 * local 19

* * * * * * controller 2993

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switch

Example: Life of a Packet

Flow Table

Group Table

Group Table

Meter Table

Next table

Action 1Action 2Action 3Next table

Action 4Next table

Action 5Output

Action set

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OpenFlow Challenges

Protocol status. OF is simple. Maybe *too* simple

Which functionalities should stay resident?

Large networks flow programming

Hi-rate flow table update

Vendors proprietary protocols

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Overlays

VLAN on traditional networks has limitations Number of instances Transport Overlapping

Some solutions have been tried HVLAN, QinQ, PBT, PBB-TE, Mac-in-mac, …

With SDN we talk about Overlay networks Used to create virtual network containers logically isolated from the

others, while sharing the underlying physical network Always based on encapsulation. Usually tunnels are terminated on

softswitch

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VXLAN

Virtual Extensible LAN Broadest industry support

VXLAN Layer 2 frames in UDP packets VLAN frames are preserved – multiple Layer 3 networks inside a VXLAN

segment Uses multicast to transport broadcasts (openflow may avoid that) Tenants see their own “normal” network Underlying network sees UDP VXLAN traffic with a segment ID VXLAN ID is 24 bits = 16 Million tenants sharing the same infrastructure

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50 Bytes More. Jumbo Frames!

14 bytes Outer MAC Header

20 bytes Outer IP Header

8 bytes Outer UDP Header

8 bytes VXLAN Header

Original L2 frame(VLAN tag included)

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Multi-tenant SDN Network

Switch Switch Switch Switch Switch Switch Switch Switch

ServerServer Server Server Server Server

vSer

ver

vSer

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vSer

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vSer

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vSwitchvSwitch vSwitch vSwitch vSwitch vSwitch

vSer

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vSer

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vSer

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SDN Controller

Network Apps/UI/…

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NVGRE, STT, NVO3

NVGRE Similar to VXLAN Microsoft pushes it Overlay of choice in Hyper-V Does not require multicast to carry broadcast, unknown unicast, multicast

Hyper-V embedded switch (Windows Network Virtualization Module) is pre-populated with all host-to-tunnel mappings by powershell CMDlets

No flooding, as there is no unknown node

STT Stateless Transport Tunneling Encapsulation leverages some specific network card capabilities, like TSO

(TCP segmentation offload) Nicira developed it. Nicira has been acquired by VMware

NVO3 Network Virtualization Overlays 3 - Developed by a group in IETF

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SDN Actual Use Cases

Link usage optimization

Distributed packet filtering

NAC for devices that do not support 802.1x

Service insertion, service chaining

Network traffic analysis, TAP aggregation

Basic link/service load balancing

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SDN Challenges

Southbound API is uncertain and will be fragmented

Scalability issues Number of flows

Performance issues Rate of flow-table updates

Redundancy

Vendors’ SDN controllers (OpenDaylight project?)

Know-how

Security

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Conclusions

SDN future is uncertain, at the moment most of the development is being done on large data centers, backbones, virtualization spaces

So far there is no real use for the enterprise

The southbound API will most probably be fragmented

It will take some time: as some analysts point out, it took server virtualization 10 years to become mainstream, while openflow 1° release was born in 2009

SDN will add up to $400M within the networking market in 2014 (Doyle Research)

In the end, the market will decide what SDN will be, where it will be used, what applications we’ll write on it

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