Virtualization and Softwarization in 5G Systems finaltomasz/seminarios_2018s2/granelli.pdf• NSSAI...

VIRTUALIZATION AND SOFTWARIZATION IN 5G SYSTEMS Fabrizio Granelli, University of Trento, [email protected]

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mailto:[email protected]

TABLE OF CONTENTS

ØVirtualization and Softwarization in Networks and ServicesØSDN, NFV

Ø4G and Evolution to 5GØLTE, 5G requirements

ØNetwork SlicingØService support, multi-tenancy

ØCloud RANØQ&A

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SOFTWARE DEFINED NETWORKING

• Separation of Control and Data Planes

Data-plane

Control-plane

Controller

Secure channel

Flow Table

OpenFlow Protocol

▸ Control logic is moved to a central controller▸ Switches only have forwarding elements▸ One expensive controller with a lot of cheap switches▸ OpenFlow is the protocol to send/receive forwarding rules from controller

to switches▸ By programming the controller, we can quickly change the entire network

behaviorà Software Defined Networking3

THE SDN PARADIGM 4

Data-plane

Control-plane

Data-plane

Control-plane

Data-plane

Control-plane

Switch

Traditional networking

Data-plane

Data-plane

Data-plane

Control-plane

Programmableswitch

Software-Defined Networking

dumb, fast

smart, slow, (logically) centralized

API to the data plane

(e.g., OpenFlow)

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SDN ARCHITECTURE, SKETCH 5

Simple forwarding HW




SDN Controller or Network OS

App App App

HW open interface - Southbound

Network control API - Northbound

5






Network OS

App App App

HW open interface

Network control API

HW forwarding abstractionlow-level primitives to describe packet forwarding

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Network OS

App App App

HW open interface

Network control APIGlobal Network view abstractionPermits programmer to focus on high level view of network topology and states

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Network OS

App App App

HW open interface

Network control APINetwork OS / SDN Controller:

Maps high level “commands” and programmer needs into low level switch configuration

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Network OS

App App App

HW open interface

Network control API

Net Apps / Services:Solve Distributed Systems problems ONCE rather than for every protocol(e.g. Dijkstra)

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Network OS

App App App

HW open interface

Network control APIA programming analogyWhat if you were to write a program which must

1) Know the details of the HW you are working on

2) Set yourself the content of each physical memory bit

Abstractions, for separating concerns and attain simplicity!

1) Machine independent language

2) Virtual memory

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OPENFLOW V1.0• If header matches an entry, corresponding actions are

performed and counters are updated• If no header match, the packet is queued and the

header is sent to the controller, which sends a new rule. Subsequent packets of the flow are handled by this rule.

• Secure Channel: Between controller and the switch using TLS

Header fields Counters Actions


… … …


Flow Table:

IngressPort

EtherSource

EtherDest

VLAN ID

VLANPriority

IP Src IP Dst IP Proto

IP ToS Src L4 Port

Dst L4Port

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FLOW TABLE EXAMPLE

• Idle timeout: Remove entry if no packets received for this time• Hard timeout: Remove entry after this time• If both are set, the entry is removed if either one expires.

Port SrcMAC

DstMAC

VLAN ID

Prio Ether Type

SrcIP

Dst IP IP Proto

IP ToS

SrcL4 Port

DstL4 Port

Action Counter

* * 0A:C8:*

* * * * * * * * * Port 1 102

* * * * * * * 192.168.*.*

* * * * Port 2 202

* * * * * * * * * * 21 21 Drop 420* * * * * * * * 0x806 * * * Local 444* * * * * * * * 0x1* * * * Controlle

r1

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ACTIONS• Controller can send flow table entries beforehand

(Proactive) or Send on demand (Reactive). OpenFlowallows both models.

• Forward to Physical Port i or to Virtual Port:• All: to all interfaces except incoming interface• Controller: encapsulate and send to controller• Local: send to its local networking stack• Table: Perform actions in the flow table• In_port: Send back to input port• Normal: Forward using traditional Ethernet• Flood: Send along minimum spanning tree except the incoming

interface• Enqueue: To a particular queue in the port à QoS• Drop• Modify Field: E.g., add/remove VLAN tags, ToS bits,

Change TTL

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FLOWVISOR• FlowVisor uses OpenFlow as a hardware

abstraction layer to sit logically between control and forwarding paths on a network device • OpenFlow provides an abstraction of the

networking forwarding path that allows FlowVisor to slice the network

“FlowVisor: A Network Virtualization Layer”, by Rob Sherwood, Glen Gibb, Kok-Kiong Yap, Guido Appenzeller, Martin Casado, Nick McKeown, Guru Parulkar, White paper, 2009.

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FLOWVISOR CONCEPT

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FLOWVISOR FEATURES

• FlowVisor intercepts OpenFlowmessages from guest controllers (1) and, using the user’s slicing policy (2), transparently rewrites (3) the message to control only a slice of the network.• Messages from switches (4) are

forwarded only to guests if it matches their slice policy

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FLOWVISOR

BEYOND OPENFLOW

• OpenFlow does not represent the only possible architecture

• Distributed SDN Control Plane (ONOS)

• P4 (high level programming language for software-based switches)

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NETWORK FUNCTION VIRTUALIZATION

“NFV is a network architecture concept that proposes using IT virtualization related

technologies to virtualize entire classes of network node functions into building blocks that

may be connected, or chained, together to create communication services”

Wikipedia: http://en.wikipedia.org/wiki/Network_Functions_Virtu

alization

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http://en.wikipedia.org/wiki/Network_Functions_Virtualization

NFV CONCEPT

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Classical Network Model:Hardware Applicances

New Network Model:Virtual Applicances

Dedicated HW/SW Platform (e.g. firewall)

Firewall SW Appliance

Commodity Hardware

VIRTUALIZATION ALTERNATIVESShips within…

Manual deployment takes…

Automated deployment takes…

Boots in…

Bare Metal days hours minutes minutes

Virtualization

minutes minutes seconds less than a minute

Lightweight virtualization

seconds minutes seconds seconds

From: http://www.socallinuxexpo.org/sites/default/ les/presentations/Jerome-Scale11x%20LXC%20Talk.pdf

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NFV VS SDN

• NFV (Network Function Virtualization) and SDN are complementary• One does not depend upon the other.

• Both have similar goals but approaches are very different• SDN needs new interfaces, control module applications.• NFV requires moving network applications from dedicated

hardware to virtual containers on commercial-off-the-shelf (COTS) hardware

https://portal.etsi.org/Portals/0/TBpages/NFV/Docs/NFV_White_Paper3.pdf

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https://portal.etsi.org/Portals/0/TBpages/NFV/Docs/NFV_White_Paper3.pdf

NFV COMPONENTS• Network Function (NF): Functional building block with

well defined interfaces and well defined functional behavior

• Virtualized Network Function (VNF): Software implementation of NF that can be deployed in a virtualized infrastructure

• VNF Forwarding Graph: Service chain when network connectivity order is important, e.g. firewall, NAT, load balancer

• NFV Infrastructure (NFVI): Hardware and software required to deploy, manage and execute VNFs including computation, networking and storage

• NFV Management & Orchestration: The orchestration of physical/software resources that support the infrastructure virtualisation, and the management of VNFs

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OPENNFV

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Operations Support System (OSS)Business Support System (BSS)Element Management System (EMS)

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OPENNFV

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VIRTUALIZATION CONCEPTS: EVERYTHING ISVIRTUAL!

Virtualization as a Paradigm

Virtual Machine

Guest OS

Guest Application

Virtual Machine

Guest OS

Guest Application

Virtual Machine

Guest OS

Guest Application

NF: Network Function VNF: Virtual Network Function NC: Network Controller VN: Virtual Network

Virtualization and

Application

Management

Hardware

Host OS

Hypervisor

Cloud Stack, Open Stack

Cloud API

VNF

VN VN NF

NF

VN

NaaS

IaaS

NC

VNC

Virtual Machine

Guest OS

Guest Application

Examples of VNFs: •  Switching: BNG, CG-NAT, routers. •  Mobile network nodes: HLR/HSS,

MME, SGSN, GGSN/PDN-GW, RNC. •  Home routers and set top boxes. •  Tunnelling gateway elements. •  Traffic analysis: DPI. •  Signalling: SBCs, IMS. •  Network-wide functions: AAA servers,

policy control. •  Application-level optimisation: CDNs,

Load Balancers. •  Security functions: Firewalls, intrusion

detection systems.

Virtual Network Functions (VNF)

2

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UE

eNodeB S-GW

MME HSS

AAA

P-GW

P-GW

AdministrativePDN

Services PDN

(Internet)S1-MME

S1-U

S11

S6a

SWx

SGi

SGi

S5/S8

S5/S8

Evolved Packet Core (EPC)Radio Access Network (RAN)

LTE IN A NUTSHELL

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UE

eNodeB S-GW

MME HSS

AAA

P-GW

P-GW

AdministrativePDN

Services PDN

(Internet)S1-MME

S1-U

S11

S6a

SWx

SGi

SGi

S5/S8

S5/S8


The MME is the key control-node for the LTE access-network. It isresponsible for idle mode UE (User Equipment) paging and taggingprocedure including retransmissions. It is involved in the beareractivation/deactivation process.

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LTE IN A NUTSHELL

UE

eNodeB S-GW

MME HSS

AAA

P-GW

P-GW

AdministrativePDN

Services PDN

(Internet)S1-MME

S1-U

S11

S6a

SWx

SGi

SGi

S5/S8

S5/S8


The SGW routes and forwardsuser data packets, while alsoacting as the mobility anchor for the user plane during inter-eNodeB handovers and as the anchor for mobility between LTE and other 3GPP technologies.

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LTE IN A NUTSHELL

UE

eNodeB S-GW

MME HSS

AAA

P-GW

P-GW

AdministrativePDN

Services PDN

(Internet)S1-MME

S1-U

S11

S6a

SWx

SGi

SGi

S5/S8

S5/S8


The PDN Gateway providesconnectivity from the UE to external packet data networks by being the point of exit and entry of traffic for the UE.

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LTE IN A NUTSHELL

UE

eNodeB S-GW

MME HSS

AAA

P-GW

P-GW

AdministrativePDN

Services PDN

(Internet)S1-MME

S1-U

S11

S6a

SWx

SGi

SGi

S5/S8

S5/S8


The HSS is a centraldatabase that containsuser-related and subscription-relatedinformation (HLR+AuC).

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LTE IN A NUTSHELL

5G IN A NUTSHELL 32

5G Disruptive

Capabilities

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� Network slicing – new value creation opportunities(vertical segments)� enables a concurrent deployment of

multiple logical, self-contained networkson a common physical infrastructure platform with devise business demands

� offers dedicated resources that can be used in an isolated, disjunctive or shared manner and a customized network operation

� supports flexible, on-demand, provision of network resources, network functions and applications, even with short lifecycles - resource physical or virtual

THE NETWORK SLICING CONCEPT

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VIRTUALIZATION AND SLICING•Network virtualization can be achieved by slicing

the available resources:• Bandwidth: each slice should have its own fraction of

bandwidth on a link• Topology: each slice should have its own view of

network nodes (switches, routers) and the connectivity between them• Traffic: to associate a specific setof traffic to one (or

more) virtual networks so that one set of traffic can be cleanly isolated from another• Device CPU: computational resources must also be

sliced• Forwarding tables

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� In composing and allocating network slicing: � Software defined control and separation of control/data plane

• Network programming via SDN APPs� Network function virtualization

and resource orchestration• (De)compose/allocate VNFs

� Flexible service chaining and service provision

� Mobile edge computing services closer to the user

� QoS provision policy� Selection of RAT / fix access� Data offloading policies

NETWORK SLICING TECHNOLOGY ATTRIBUTES

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HSS

PCRFMME

AAA

SGW + PGWU.P.

SGW + PGWC.P.

eNB + gNB

4G Arch

NSSF

DN2UPF2

Network Functions:-UDM: Unified Data Management-AUSF: Authentication Server Function-PCF: Policy Control Function-AMF: Core Access and Mobility Management Function-SMF: Session Management Function-UPF: User plane Function-DN: Data network, e.g., operator services, Internet access-(*) NSSF: Network Slice Selection Function

Interfaces:-NG1: NAS-NG2: AN-CN C-plane-NG3/NG9: per PDU Session tunnelling-NG7/8/10-15: C-Plane Service-based interface

3GPP NETWORK SLICING ARCHITECTURE

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BASE STATION VIRTUALIZATION

• eNB virtualization in LTE: • via hypervisor means that shares

resources among different MNOs• consider radio conditions, sharing

contracts and traffic load

• Network Virtualization Substrate (NVS) operates closely to MAC scheduler and adopts a two-step process: • one managed by the infrastructure

provider for controlling the resource allocation towards each virtual instance of an eNB

• the second controlled by each VMNO providing scheduling customization for allocated resources

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3GPP RAN FOR NETWORK SLICING

• Slice preference / Selection • The UE sends a RRC request specifying the Network Slice Selection Assistance

Information (NSSAI) indicator(s).• NSSAI has clear definition in SA2 TR 23.799 and TS 23.501.• NSSAI is a vector of slice ID preferences (e.g., slice-ids) the UE would like to join.• NSSAI information are pre-coded on the SIMcard (like the IMSI information) and

cannot be selected (for the moment) by the device user interface.• For signaling between RAN and CN a Slice ID is represented by an NSSAI or SM-NSSAI.

For the air interface, it is up to RAN groups to decide how to carry NSSAI information in RRC.

• In the RRC Connection Response, the eNB notifies the UE with allowed/accepted NSSAI, which will be stored and use for future messages.

RRC Connection Req.

RRC Connection Resp.

AMF Selection

Slice Availability

• Mobility• Slice availability during mobility, e.g.,

• Neighbours may exchange slice availability• core network could provide the RAN a mobility

restriction list• source gNB needs to pass on slices that a UE in

question is using to a target gNB• target AMF is responsible for removing (or

inactivating) at NAS level any slice no longer supported at the target node.

• Heterogeneous Slice Structure• Same number of slices available in the same

Tracking Area (or specified cell cluster)• AMF can deattach the UE from a specific slice,

e.g., Netflix when is not used.• HO procedures are required when moving to

areas with different slice availability, as AMFshould be changed.

• Different PDN-Ips can be assigned tothe same UE over time.

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E2E SLICING CONCEPTJournal of Information Processing Vol.25 153–163 (Feb. 2017)

Fig. 1 End-to-end slicing concept [41].

radio boundary, so called mobile packet core slicing and RAN(Radio Access Network) slicing. Each network slice is made upof a virtualized air-interface, radio access network and mobilepacket core network, and transport network combined. We alsonote that mobile fronthaul and backhaul network slicing need tobe considered as well.

3. Packet Core Slicing

There are several research efforts to slice packet core networksusing virtual machines on top of white boxes with general pur-pose processors and network processors as well as FPGAs. Inthis section, we first review the components of packet core net-work and introduce our preliminary research efforts on slicingpacket core networks using deeply programmable network nodeswith general purpose processors and network processors, calledFLARE programmable nodes [6] and FPGA boards with Ope-nAirInterface (OAI) [39] on top of them.

3.1 Packet Core NetworkIn 3GPP, the current generation Evolvable Packet Core (EPC)

network has been designed and standardized as a flat architec-ture, where IP (Internet Protocol) is the only protocol to transportall services. A User Equipment (UE) can get Internet connectiv-ity when connected to EPC over RAN (radio access network). Inconsidering end-to-end network slicing, we must fist study packetcore network slicing as an extension to well studied transport net-work slicing, such as transport SDN.

3.2 MVNO as Precursor to SlicingMobile Virtual Network Operators (MVNOs) that obtain sliced

RAN resources from Mobile Network Operators (MNOs) act as aforerunner in mobile network slicing, which is a key technologyin the evolution towards 5G cellular wireless networks. Compar-ing to the traditional MNOs, MVNOs don’t need to build theirown RAN but focus on building new business models and newvalue-added network functions in their packet core networks.

We believe that an in-depth study of MVNO network not only

Fig. 2 Underlying infrastructure of FLARE [6].

help the current MVNOs improve their services but also benefitthe 5G research and development in terms of network slicing, es-pecially for allocating isolated resources for different applicationsand services.

For example, in Refs. [25], [37], we create application specificslices and characterize the flow properties of popular mobile ap-plications. We have studied how to create per-application sliceswithin an MVNO using deeply programmable FLARE [6] nodes.Since the data plane of our MVNO is enabled to be deeply pro-grammable by FLARE nodes, from given flows observed at thedata plane, we can identify applications that transmit those flowswith 100% accuracy. We also develop an application-specificin-network processing mechanism to optimize MVNO networkthrough applying different virtual network functions to differentapplications.

3.3 FLARE Programmable NodeFLARE [6] is an open deeply programmable node architecture

that can concurrently run multiple isolated virtual network func-tions on a physical node. As shown in Fig. 2, a FLARE nodeconsists of a combination of many-core network processors andIntel x86 processors. With various virtualization techniques, weslice both resources (CPUs, memory and link bandwidth) in bothmany-core processors and x86 processors. We define sliver as a

c⃝ 2017 Information Processing Society of Japan 155

A. Nakao, et al., “End-to-end Network Slicing for 5G Mobile Networks,” J. Of Information Processing, Vol. 25, pp. 153-163, Feb.’17.39

� 5G Network slice broker� Perfrom admission control based-on

indicated SLA � Use Itf-N and Itf-B to monitoring KPIs and

configure slice on RAN � Receive on-demand slice request from

• MVNOs via the Type 5.• verticals and OTT providers, through SCEF

� Itf-N, Itf-B and Type 5 interface enhancements: � PLMN-id or vertical-id � type of resources and QoS� starting time, duration or periodicity � amount of resource blocks or capacity � size of file to be downloaded� mobility (stationary, low, medium, high) � service disruption tolerance� performance measurement info

MULTI-TENANCY SUPPORT IN 3GPP NETWORKS

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CLOUD RAN - DEFINITION• C-RAN (Cloud-RAN), sometimes referred to as Centralized-RAN, is a

proposed architecture for future cellular networks.• Motivation: BTS are designed to handle the maximum traffic, not average

traffic, resulting in a waste of processing resources and power at idle times à a more flexible solution is needed.

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BBU Pool RRH

RRHRRH

Fronthaul links

C-RAN CONCEPT

• C-RAN may be viewed as an architectural evolution of the above distributed base station system.

• It takes advantage of many technological advances in wireless, optical and IT communications systems.• It uses the latest CPRI standard, low cost Coarse or Dense Wavelength Division

Multiplexing (CWDM/ DWDM) technology, and mmWave to allow transmission of baseband signal over long distance, thus achieving large scale centralised base station deployment.

• It applies recent Data Centre Network technology to allow a low cost, high reliability, low latency and high bandwidth interconnect network in the BBU pool.

• It utilises open platforms and real-time virtualisation technology rooted in cloud computing to achieve dynamic shared resource allocation and support of multi-vendor, multi-technology environments.

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CLOUD RAN ARCHITECTURE

• Large scale centralized deployment:• It allows hundreds of thousands of remote RRH connect to a centralized BBU

pool. The maximum distance can be 20 km in fiber link for 4G (LTE/LTE-A) system, even longer distance (40 km~80 km) for 3G (WCDMA/TD-SCDMA) and 2G (GSM/CDMA) systems.

• Apparently, some Asia operators have deployments of C-RAN systems with 1200 RRHs centralized to one central office.

• Native support to Collaborative Radio technologies:• Any BBU can talk with other BBU within the BBU pool with very high bandwidth

(10Gbit/s and above) and low latency (10us level). This is enabled by the interconnect of BBU in the pool.

• This is one major difference from BBU Hoteling, or base station hoteling. In the latter case, the BBU of different base stations are simply stacked together and has no direct link among them to allow physical layer co-ordination.

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CLOUD RAN ARCHITECTURE

• Real-time virtualization capability based on open platform:• This is different from the traditional base station built on proprietary hardware,

where the software and hardware are closed-sources and provided by one single vendor. C-RAN BBU pool is built on open hardware, like x86/ARM CPU based servers, plus interface cards to handle fiber link to RRH and inter-connection in the pool.

• Real-time virtualization make sure the resources in the pool can be allocated dynamically to base station software stacks, say 4G/3G/2G function modules from different vendors according to network load.

• To satisfy the strict timing requirement of wireless communication system, the real-time performance for C-RAN is at the level of 10s of micro-seconds, which is two magnitude higher than the milli-second level 'real-time' performance usually seen in Cloud Computing environment.

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CONCLUSIONS

• This seminar introduced SDN and VNF methodologies

• 5G seems a relevant scenario where such technologies will be implemented

• Several aspects need to still be analyzed

• Open topic, both for research and implementation/deployment

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ANY QUESTIONS?

Fabrizio [email protected]

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mailto:[email protected]

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