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Cisco “5G Ready” Transport

Waris Sagheer, Simon Spraggs, Dennis Hagarty 14-Nov-2018

© 2017 Cisco and/or its affiliates. All rights reserved. Cisco Public

GSX FY19

Timing and synchronization

Welcome & Introduction

Summary

5G challenges for transport

A 5G transport ready infrastructure Agenda


Business Landscape

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2015 2016 2017 2018 2019 2020

Mobile ARPU, Multiple Countries

Source: EU Commission

Consumer ARPUs are Declining or Flat B2B or B2B2x Market Has Future Growth

Emergence of Low Latency Need for

better QOE and to Enable New Applications


5G challenges for transport


Source: Recommendation ITU-R M.2083

5G Key Use Case Categories

• Focused on low power wide area NB-IoT with high connection density and energy efficiency

• For mission critical use cases (self driving, Public safety, ...)• Desired 1ms access time only refers to radio interface and

would be most useful in near field mission critical apps

• Extra capacity delivered through new 5G frequency bands • Not too concerned with connection density or latency.

Enhanced Mobile Broadband (inc. Fixed Access)Increased Bandwidth

and Capacity

IoT/massive Machine Type Communications Slicing, Flexible deployment, NFV/Virtualisation

Push data plane to the edge,Intelligent in Network

Ultra-Reliable Low Latency


Distributed workloads to the edge of the network driven by low latency applications, lower transport costs, QOE

Any-to-any connectivity between distributed UPFs and with centralized UPF&CP

Ability to run multiple logical networks as virtually independent

Simultaneous support of strict SLA & best effort traffic over same infra

Dynamic and flexible slicing creation/modification

Unified Network Fabric, Network Programmability & Automation, Strict QoS, Convergence

MEC/CUPS Network Slicing CRAN

Introduction of RAN splits and virtualization of RAN workloads

Low latency and high throughput access networks

Distributed workloads to different levels of the transport network

5G Transport - Technology Evolutions


D-RANBACKHAUL

C-RANBACKHAULFRONTHAUL

C-RANBACKHAULMIDHAUL

C-RANBACKHAULMIDHAULFRONTHAUL

RU/DU/CU

RU

eCPRI v.high b/w, µsec delay

RU/DU

F1: ~user b/w, msecs delay

Nx, ~user b/w, msecs delays

Nx, ~user b/w, msecs delays

RU

eCPRI v.high b/w, µsec delay F1, Nx, b/w=user rates, msecsdelays

Nx: user b/w, msecs delay

DU vCU

vCU

EdgeAggregationPre-AggCell site

DU/vCU

vUPF

vUPF

vUPF

vUPF

5G Transport - RAN impacts Transport Design


5G ready transport architecture


Cisco’s overall 5G transport proposition

Ω

Access Core

Switched DWDM

Aggregation

DCPre-

Aggregation

Transport control / orchestration

Telco/ITDC Domain

DC

Dark Fiber / WDM

Mobile Core Control / orchestration

EnterpriseConsumerSMB

CPEs

Mobile Network SliceManager

Big data / automation

Edge

Use Cases

Controllers / Automation / Telemetry /Analytics

Access control / orchestration

BGP-VPN L2/L3 + Overlay VPNs

Multi-serviceFlexible radio / mobile core / service placement

End2end packet infrastructure

Up to x10 radios (500k n/w devices)x4 – x100 bandwidth than 4GMulti-Access Edge Compute

Segment Routing


Physical Network Evolution

Access CoreAggregationPre-Agg

Peering

200K n/w devices

Access CoreAggregationPre-Agg EdgePeering

GW

Optical Cut-through

Multi-degree ROADM

• MEC demands IP switching capabilities where ever there is DC

• Traffic demands are lambda level and above

• MEC creates discrete optical domains, reduces optical drive distances and simplifies optical infrastructure

• Open ROADM, pluggable DWDM optics driving new round of IP optical integration

1-10Gbps10-100Gbps

>100Gbps

10-100Gbps >100Gbps >400Gbps >400Gbps

Passive or dark fibre

Multi-degree ROADMs

Today

Future


Access

Aggregation

Logical Network Evolution: Todays Service Creation

HW Appliances

Legacy Central Office

Metro Network Domain Core Network Domain Data Center Domain

Limited Cross-domain Automation

Centralized Delivery of Services

VNF

IPMPLS

L2VPN

Ethernet

L3VPN VXLAN

E2E service provisioning is lengthy and complex:

Multiple network domains under different management teams Manual operations Heterogeneous Underlay and Overlay networks

VNF


Logical Network Evolution:5G Infrastructure

Metro Network Domain Core Network Domain Metro Network Domain

LDP

RSVP

IGP

BGP-LU

LDP

Intra-Domain CP

FRR or TE

Inter-Domain CP

L2/L3VPN Services

IGP with SR

BGP

IGP with SR

BGP-LU

EPN 4.0 EPN 5.0 Metro Fabric

BGP LDP BGP

EVPN L2 & L3 VPN

Segment Routing

SR PCENSO XWWAE


Network Resiliency TI-LFA and automated 50ms protection

ScalabilityMultidomain architectureOn-Demand Nexthop (ODN)Stateless within core

Service Aware underlayTraffic SteeringAutomated Traffic Steering

End to End path control Shortest PathFlex-algoMulti—domain TESR-PCE + Distributed CP

Network SimplificationEliminate LDP, RSVP and other protocolsStateless core devices

Simplified Service Creation Concurrent support for network and overlay VPNs

OAM and performance managementUnderlay and service monitoringReal time adjustments based on PM

Standards Based No vendor lock-in

5G Transport: Why Segment Routing


SR: Engineering the Underlay

• Flex-Algorithm

Builds domain level forwarding tables

IGP distributes multiple metrics / affinities

Multi-algorithms operational in network

SPF, Low Latency, constrained nodes / links (customer chooses)

TiLFA per algorithm

• SR Policies (or SR-TE)

Builds paths between nodes

Path computation based multiple constraints (b/w, latency, affinity)

Calculated by head-ends or an SR-PCE

Multi-domain / disjoint paths require SR-PCE

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7

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1, green, 74

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6

3

8

1

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5 90

23

14

9Alg128

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85 9

Alg129

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Alg0

2

Example Green: Low latency, Red: IGP path


Segment Routing – Service Aware Traffic Steering

10.10.10.0/24 NH=7 color=GREEN20.20.20.0/24 NH=7

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1, green, 742

20.20.20.0/24 (standard)

10.10.10.0/24 (low delay)Traffic for

10.10.10.1 – NH 7 and

20.20.20.1 - NH 7

IGP

Delay optimized

10.10.10.0/24

20.20.20.0/24

RR

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3

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1, green, 742

IGP

Delay optimized10.10.10.0/24 FC1

20.20.20.0/24 FC0

Ingress classification DSCP = EF FC = 1 GreenDSCP = AFxx FC= 0 IGP

Traffic for 10.10.10.1

10.10.10.0/24EF= Low delay Everything else IGP

Destination based

Flow based

• Traffic Steering

Mechanism on source router to steer traffic

By default traffic uses IGP path

Can steer traffic into a SR policy or specific Flex-algos

Destination TS : destination only

Flow based TS : destination + QoS criteria

• Automated Traffic Steering

Hints on SR policy conveyed in overlay route updates

Significantly reduces configuration

Uses BGP color extended community (RFC 5512)


SR Path Computation Element (SR-PCE)

Solution

Multi-Domain SRTE VisibilityCentralized SR-PCE for Multi-Domain Topology view

Integration with ApplicationsNorth-bound APIs for topology/deployment

Delivers across the unified SR Fabric the SLA requested by the service

Benefits

SRTE Head-End

Simplicity and AutomationEnd-to-End network topology awarenessSLA-aware path computation across network domainsDisjoint pathsMulti-domain path computation and ODN

Distributed Mode – SR-TE Head-EndVisibility is limited to its own IGP domain

DeployCollect

TopoDB

Compute

REST API

IGPBGP-LS

BGP

PCEP

Single / Multi-Domain Topology

Native SR algorithms

SR-PCE runs on virtual or physical IOS-XR node

APP APP APP

Metro Core Data Center

Aggregation

Access Metro

1 2 3 4


Is Diffserv QoS “Good Enough” for 5G • Yes, as a transport QoS strategy!

Slice b/w / class protection through ingress conditioning and marking

Class separation and protection with core scheduling

Bandwidth reuse

QoS aware capacity planning

• FOR LOW LATENCY SERVICES THE OVERALL DESIGN NEEDS CONSIDERATION

Network delay = propagation delay + switching delay + scheduling delay + serialization delay

• Proximity of gateway functions to users

Reduce propagation delay and OEO delays

• Proximity of applications to users

Reduce propagation delay and OEO delays

• Serialization delay is a consideration for fronthaul applications (TSN)


Service Infrastructure

• Network based VPNs

• 5G based VPNs

• Overlay / SDN-WAN based VPNs

• Enterprise services

• Inter-DC communications

Service config

CE

BGP RR

CE

SD-WAN controller

CECE

SR-PCE

SR-PCESR-PCE


Transport level 5G slicing


Edge DC Far Edge DC

MPLS/SR UNDERLAY

Example: 5G backhaul dataplane slice

e/gNB

e/gNB

e/gNB

AF

Peering

Internet VPN

Enterprise VPNs

PE

3GPP control Plane L3 VPN

Access CoreAggregationPre-Agg

EdgeEdge DC

Regional DC

3GPP controlservers

Central DC

Backhaul (N3)E-LAN or L3 VPN

UPF


• Small number of slice planes defined in underlay (across domains)

5G mobility slices (eMBB, URLLC, mIOT, signalling, etc.)

Major Service Type (Wholesale, MVNO, Enterprise, Content, etc.)

• Diffserv QoS enabled network

• Each Slice plane characterized by

Optimization + constraint objective : latency, bandwidth, reliability,

• Based on a flex-algorithm (SPF included) or pt-2-pt SR policies

Slicing in the Underlay Based on SLA Requirements

Slice 1

Slice 2


Mapping Customers to Underlay Slice Planes

Slice 1

Slice 2

• L2/L3 VPNs used for customer and service separation

• Potentially large numbers

• Traffic classified and controlled on ingress

• Automated Steering place VPN traffic into correct underlay slice plane


Timing and Synchronization


• 5G (like modern LTE-A networks) requires phase synchronization

• New 5G TDD radios definitely require it: 3GPP: 3µs between base stations (for TDD, LTE-A radio co-ordination)

Radio backhaul network: ±1.5µs from reference time

Timing and Synch – New Phase Requirements


• 5G is also re-engineering the Fronthaul network towards Cloud RAN:• CPRI to packet-based Fronthaul/Midhaul impacts timing

• Much tighter requirements for phase alignment budget

Timing and Synch – Fronthaul

Fronthaul

vBBU

WAN/Backhaul

Mobile Core

RU

RU

RU RU

RU

RU

RU: Remote Unit

Backhaul

WAN/Backhaul

Mobile Core

eNB

eNB

eNB eNB

eNB

eNB

RU: Remote Unit

Backhaul

Distributed RAN

CentralizedRAN

Midhaul

DU

Fronthaul

CU

DU

WAN/Backhaul

Mobile Core

RU

RU

RU RU

RU

RU

RU: Remote Unit

Centralized Unit

Distributed Unit

CloudRAN

CPRI


• Great solution: G.8275.1 with “on path support” for PTP• Needs good network design in combination with SyncE• End-to-end timing “budget” with accurate boundary clocks

• PTP/SyncE as a backup to GNSS receiver outages• GNSS where it’s cost effective, PTP everywhere else

• Effective solution where site conditions allow (Sky view, $$)• Susceptible to jamming (and increasingly spoofing)• Time source for cell sites, PTP GM’s and monitoring equipment

GNSS (GPS, Galileo) Receivers Include GNSS receivers inside routers where appropriate

PTP/1588 and SyncE in Transport NetworkRouters as high performance

T-BC boundary clocks with Class B/C G.8273.2 performance

Flexibility in the design of the equipment allows them to be

used in any situationAll of the Above

Timing and Synch – Solutions

Galileo photo © GSA


• There are various profiles available for use

• Most operators looking at G.8275.1 – the best timing solution

• Supported across ASR900, ASR920, NCS500, NCS5500, ASR9K range

Timing and Synch – PTP Profiles for Phase

T-BC-P

PTP unaware

“G.8265.1 like”

Ethernet Multicast

IPv4 UnicastIPv6 optional

T-TSC-P

T-TSC

PTP awarebackhaul network

T-GMT-BC

PTP with full on-path timing support, G.8275.1 Telecom Profile

T-BC T-BC T-BC

PTP unaware

“G.8265.1 like”

T-GM

PTP with partial timing support, G.8275.2 Telecom Profile


Summary


• 5G brings new requirements and challenges to transport network

• Cost and simplicity is critical

• Outlined Cisco approach to 5G transport networking

• Streamlining network structure and packet optical integration

• Segment Routing for engineering and simplifying the underlay

• Concurrent support for BGP based VPNs and SD-WAN solutions

• Timing and synchronization is a vital component of the radio network

• Operators are investing in 5G-ready networks now!!

Summary


The End

Need more information??

Cisco’s SP Mobility Page: https://www.cisco.com/c/en/us/solutions/service-provider/mobile-internet/index.html

5G xHaul White Paper:https://www.cisco.com/c/m/en_us/network-intelligence/service-provider/digital-transformation/converged-5g-xhaul-transport.html

Compass "Metro Fabric Design” https://xrdocs.io/design/EPN5.0 & EPN4.0: https://www.cisco.com/c/en/us/solutions/enterprise/design-zone-service-provider/programmable-network.html

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