SDN in SP WAN TECH-SDN-SP

David Jakl Systems Engineer

Agenda

SDN in SP WAN

Multi-Layer SDN

PCEP

BGP Link State

BGP Flowspec

Segment Routing

Summary

SDN enables IP/MPLS evolution to a hybrid control-plane centralized control improves network operations and optimization

Applications Applications

Controller

Evolution

Applications Applications

• Distributed Control remains best for many use-cases; e.g. IGP convergence

• Centralized Control introduces new value; e.g. TE placement optimization

4

SDN WAN Transport – Use Cases

• Global Load Balancing

• Multi Layer Optimization

• Coordinated Maintenance • LSP splitting and merging

• Network Rearranging

• Segment Routing

Optimization

• Bandwidth Calendaring with Hybrid Cloud

• Premium Bandwidth

• Path Diversity • Latency Based Forwarding

Monetization

5

Another Perspective of Offline vs Online SDN WAN Orchestration

When the planning inputs change almost on a hourly basis and the network load is close to the max-link-load objective

Tra

ffic

change fr

equency

annual

quarter

monthly

weekly

daily

hourly

Load / Link

25% 50% 75% 100%

Planning

(offline)

SDN WAN

(online)

Source: Clarence Filsfils

6

NB API

Plan

Optimization &

Prediction

Analytics

Collector Deployer

Calendaring

Orchestration

Our SDN WAN Orchestration Platform Evolving …

Optical

IPv4/IPv6/MPLS Segment Routing

Apps

RESTCONF

7

SDN WAN Orch Use-Case #5: Maintenance Window Scheduling

SDN WAN Orch

Collector Deployer

NB API

WAN

R1

R2

R3

1

4

Customers DC/Clouds

① Network conditions reported to collector

② Ops selects Ra, Rb and maint window time

③ Maint Window request: <Ra, Rb, Window>

④ SDN W-O returns impact and changeover plan. Ops confirms

⑤ At Maint Win start SDN W-O re- arranges traffic to bypass Ra, Rb

2

3

PCEP 5

8

Ra Rb

Ops

The Multi-Layer Optimization – nLight

The new DWDM layer enables a truly Converged IP+Optical Transport

Scalable more than 8Tb/s per fiber, based on 100+Gb/s DWDM channels

Flexible, fully non-blocking wavelength switching

BUT…

– Past: Optical BW was relatively cheap throw optical BW at the problem

– Future: Optical BW most expensive part of CapEx need to use it efficiently

SDN transport enables Converged network optimization

– SLA aware routing (e.g. min Latency) or Cost aware routing (e.g. min regens)

– Link failure Restoration can lead to 20+% savings, by reusing available router ports

SDN innovation most important for Converged Transport

The IP/MPLS evolution to SDN is an important innovation!

Optical control, always mainly centrally controlled (NMS)!

SDN Controller (WAN O)

9

Multi-Layer IP/Optical PCE Models (Examples)

Separate PCE

– Operates on each layer

– Optional inter-layer PCE communications

Single-Layer PCE

– Visibility into L3 and optical topologies

– Programs L3 and L3 UNI to optical

10

VNTM = Virtual Network Topology Manager

SDN WAN Use-Case #9: SDN WAN Orch Triggered GMPLS Setup

SDN WAN Orch

Collector Deployer

NB API

R1 R2

1

2

3

① Realtime data collection reveals trending congestion (Rc-Rb link) imminent

② Ops App requests Multi-layer optimization

③ SDN W-O programs Ra and Rb to initiate GMPLS Setup

④ New Ra-Rb link is injected into IP/MPLS Topology

ML Path

Optimization App

Ra Rb

Rc

O1 O2

Congested!!

PCEP

GMPLS UNI GMPLS UNI

4

11

Ops

PCEP BGP Link State BFP Flowspec

12

PCE Architecture

Addresses complex requirements for path computation in large, multi-domain and multi-layer networks

Path computation element (PCE) – Computes network paths based on network information (topology, paths, etc.)

– Stores TE topology database (synchronized with network)

– May reside on a network node or on out-of-network server

– May initiate path creation

– Stateful - stores path database included resources used (synchronized with network)

– Stateless - no knowledge of previously established paths

Path computation client (PCC) – May send path computation requests to PCE

– May send path state updates to PCE

PCC and PCE communicate via Path Computation Element Protocol (PCEP)

Cisco innovation, standardization started in 2005

First implementation (stateless PCC/PCE on network nodes) released in IOS XR 3.5.2 for inter-area TE

Cisco WAN orchestration provides network path instantiation driven by an out-of-network stateful PCE

13

H E L L O my name is

PCE

Stateful PCE

Introduces PCEP extensions for

– LSP state synchronization betw een PCCs and PCEs

– PCC delegation of LSP control to PCE

Passive stateful PCE – PCC maintains state synchronization w ith PCE

– PCC exclusively controls LSP

– PCE does not modify LSP state

Active stateful PCE – PCC maintains state synchronization w ith PCE

– PCC may delegate LSP control to PCE

Either PCE or PCC can initiate LSP setup

PCC always owns LSP state

Cisco WAN orchestration solution relies on an active stateful PCE that initiates LSP setup

14

PCEP

Stateful PCE

TED

LSP DB

PCC

PCE-initiated

LSP

BGP Link State

15

BGP may be used to advertise link state and link state TE database of a network (BGP-LS)

Provides a familiar operational model to easily aggregate topology information across domains

New link-state address family

Support for distribution of OSPF and IS-IS link state databases

Topology information distributed from IGP into BGP (only if changed)

Support introduced in IOS XR 5.1.1

draft-ietf-idr-ls-distribution

BGP Flowspec for SDN WAN Orchestration

Define classification and action semantics in BGP called Flow Specifications (Flowspec)

Leverage BGP control plane and transport for efficient, scalable flowspec announcements and withdrawls

Enhanced actions:

– Traffic-rate

– Traffic-action (includes sampling, logging)

– Redirect (NH, VRF)

– Traffic-marking (DSCP)

RFC 5575

IOS XR 5.2.0

16

OffRamp in “Dirty” VRF: How FlowSpec helps?

• More granular, only the protocol/port/packet-size… is diverted in Dirty VRF

• Simple and scalable

Controller

Victim

2.1.1.1

A B

C

D

E

F

G

H

I

K

J

L

M

S

@TMS

RR

IPv4

BGP FS Match: dest-IP: 2.1.1.1

+ dest-port: 80

Action: NH: VRF Dirty

BG

P F

S

VRF dirty

0.0.0.0/0

nh: @TMS sta

tic

VRF dirty

0.0.0.0/0

nh: @TMS sta

tic

Match: dest-IP: 2.1.1.1

+ dest-port: 80

Action: NH: VRF Dirty

Segment Routing

18

Balance of Distribution and Centralization

RSVP-TE Non-optimum, non-predictable,

and experienced as too complex

OpenFlow Scalability?

Deployability within 18months?

Balance Distribution-only Centralized-only

Oct12 Mar13 Jul13 Nov 13 Mar14 Jul14 Nov 14

Cisco

presents SR

at MPLS WC

with demo

Cisco

releases 2

IETF drafts

on SR

ALU/Ericsson

join

Cisco NAG

Operator

Group

Formed

Cisco

releases a

total of 8 IETF

drafts on SR

JNPR joins

Cisco

presents

TI-LFA with

demo

12 IETF drafts

SPRING WG

One-year

first-public

presentation

birth day

SR/TE first

public demo

15 IETF drafts

FCS SW

More !

Much

More !

www.segment-routing.net

Confirmed Operators: Orange, Facebook, Google, Telstra, Goldman, BT, Belgacom, TW, Comcast, Liberty, SFR… Interested Operators: DT, TI, Telefonica, Cox, Century Link, Reuters, Barclays, Sky… Confirmed use-cases: SDN/TE, FRR, EPE, DC, DC2WAN service integration, Access/MetroE XR and XE roadmap

21

• Simple extension to IS-IS or OSPF, automatically builds and maintains Segments

Nodal Segment – A Shortest path to the related node

Adjacency Segment – One hop through the related adjacency

• Excellent Scale: a node installs N+A FIB entries

N = nodal segments; A = adjacency segments

A B C

M N O

Z

D

P

Nodal segment to C

Nodal segment to Z

Adj Segment

Nodal segment to C

22

• Node Z advertises its node segment (loopback 0)

e.g. in ISIS its just a simple ISIS sub-TLV extension

• All remote nodes install the node segment to Z in the MPLS dataplane

A B C

Z

D

65

FEC Z

push 65

swap 65

to 65

swap 65

to 65 pop 65

A packet injected anywhere

with top label 65 will reach Z

via shortest-path Packet to Z Packet to Z

65

Packet to Z

65

Packet to Z

65

Packet to Z

23

• Node C allocates a local label for CO link segment

• C advertises the adjacency label in IGP

e.g. for ISIS, it’s a simple sub-TLV extension

• C is the only node to install the adjacency segment in MPLS dataplane (FIB)

A B C

M N O

Z

D

P

Pop

9003

A packet injected at node C

with label 9003 is forced

through datalink CO

24

• Source Routing along with the explicit path, stack of nodal and adjacency segments

• Any explicit path can be expressed: e.g. ABCOPZ

• ECMP

Node segment

• Per-flow state only at head-end

not at midpoints

• Source Routing

the path state is in the packet header

A B C

M N O

Z

D

P

9003

Packet to

Z

65

9003

Packet to

Z

65

Packet to Z

Packet to Z

65

Packet to

Z

65

9003

72

Packet to

Z

65

9003

72

72 72

65

65

25

• Efficient packet networks leverage ecmp-aware shortest-path!

node segment!

• Simplicity

no complex LDP/ISIS synchronization to troubleshoot

one less protocol to operate

A B

M N

PE2 PE1

All VPN services ride on the node segment

to PE2

IPv4 over MPLS/IGP VPN over MPLS/IGP

Internet over MPLS/IGP PW over MPLS/IGP

IPv6 over MPLS/IGP

26

• SR router scales much more than with RSVP-TE

The state is not in the router but in the packet

Node + Adj vs. Node 2̂

• No requirement of RSVP-TE protocol

And knobs such as LDPoRSVP etc.

PE

PE

PE

PE

PE

PE

PE

PE

P

In Label Out Label Out

Inter face

L1 L1 Intf1

L2 L2 Intf1

… … …

L8 L8 Intf4

L9 Pop Intf2

L10 Pop Intf2

… … …

Ln Pop Intf5

Node Segment Ids

Adjacency Segment Ids

FIB remains constant

27

draft-francois-segment-routing-ti-lfa

• Guaranteed Link/Node FRR in any topology

even w ith asymmetric metrics

• No Directed LDP session

• Simplicity

entirely automated (no need for customization)

• Incremental deployment

Applicable to LDP and IP primary traff ic

Only the repair tunnel is SR-based

• For networks with symmetric metric & link protection

No extra computation

Simple repair stack

Node segment to P node

Adjacency segment from P to Q

• Demo available

Backbone

C1 C2

E1 E4

E3 E2

1000

Node segment to P node

Default metric: 10

Adj segment to Q node

28

SR with WAN Orchestration

WAN O allows for the best possible simplification of SR

– Optimum state computation

– A single touch-point at the Source Node

– Instant set-up time

Also a stateful PCE, as with MPLS-TE, can be help to:

– Compute globally optimum paths for traffic-engineered SR tunnels

– Instantiate SR tunnels based on requests from applications

– Instantiate traffic steering onto the instantiated tunnel

Minimal changes – PCEP capability to negotiate SR between PCE and PCC

– IGP capability used by PCE’s to advertise their SR/PCE capability

– Extension to BGP-LS to convey the segments

– Extension to IR2S policy retrieval to include segment information

– Minimal changes in (Cisco) CLI and look and feel stays same

1 0

B

Ask for path to G

with certain SLA

(delay, bandwidth,

duration, etc)

SDN WAN O

Indentify best

path and

segments (B, D,

C, E, G)

A

D

C

F

E

G

29

Summary

30

Summary

SDN WAN

PCEP

BGP Link State

BGP Flowspec

Segment Routing

Orchestrated Networks

Network-aware Apps

Programmatic Interfaces (& Overlays)

Segment Routing,

IP+Optical Convergence

Technology Objectives

Make everything go faster, easier and more agile

Configurable Networks

Apps-aware Networks

Network Interfaces

Simplify Networks

32

Scenario 1: Using ECMP

Scenario 2: Using One Path of ECMP

Scenario 3: Using Anycast Segment

Scenario 4: Not Using Shortest Path

Scenario 5: Traversing Links

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