Dynamic composition of virtual network functions in a cloud environment

Alma Mater Studiorum - Universita di Bologna

Dynamic composition of virtual network functions in cloudenviroments

SupervisorProf. Eng. Walter Cerroni

Assistant SupervisorsEng. Chiara Contoli

Eng. Giuliano Santandrea

Candidate

Francesco Foresta

3rd March 2015

Summary� Introduction

� Cloud Computing� Network Functions Virtualization (NFV)� Software Defined Networking (SDN)� OpenStack

� Case Study: Dynamic Service Chaining� Network Topology: L2 Level

� Implementation� Measurements

� Network Topology: L3 Level� Implementation

� Conclusions

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Francesco Foresta - Dynamic composition of virtual network functions

Context� In the last few years Telecommunications networks infrastructures

has been gradually modified� networks resources have been moved from the core to the edge of the

network itself, as close as possible to the end user (edge networks)� it’s expected that in the next future the core networks will be only a

combination of high-bandwidth connections between those edgenetworks

� In this kind of scenario, it will most likely take place the CloudComputing paradigm where network resources are offered from aprovider to a client as a service in a way which is similar toelectricity, telephones, gas, water.

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Cloud Computing

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Network Functions Virtualization (NFV)

The application of cloud computing to the edge networks lead up toorigin of NFV:� The original Internet paradigm is focused on packet forwarding

based on IP addresses, but in current IP networks packets areprocessed in intermediate nodes, called middle-boxes

� Each middle-box is tipically hardware, expensive and proprietary:� vendor lock-in problem: the client is dependant from the provider� Internet ossification: complexity of providing new services

� In 2012 a group part of the ETSI published a white paper: theproposal is to virtualize network functions on general purposehardware, simplifying middle-boxes

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Software Defined Networking (SDN)

All those approaches require a certain dinamicity and flexibility attraffic management level:� SDN: it’s a new approach to computer networking that allows

network administrators to manage network services throughabstraction of low-level functionality, standardised by Berkeleyand Stanford Universities in 2008� SDN architectures decouple network control and forwarding functions� It enables network control to become directly programmable and the

underlying infrastructure to be abstracted from applications andnetwork services

� The OpenFlow protocol lets to communicate network plane withthe data plane: it enables remote controllers to determine thepath of network packets through switches that made the network

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OpenStack

� It’s an Open Source joint project of Rackspace Cloud and NASA,assisted by more than 200 companies from the IT industry.

� It allows to manage cloud platforms: these are cluster of physicalmachines which contains some servers that will be offered as aservice to a client, in according to the IaaS(Infrastructure-as-a-Service) paradigm

� A user can create a virtual network infrastructure (VNI) composedof instances (implemented as virtual machines) and networksappliances (routers, firewalls, etc) in a simple and efficient way

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OpenStack: Components and abstractions

� OS is composed of some components: every component works ina specific area (networking, compute, identity, etc).

� Neutron (networking) defines these networks abstractions:� Network : an isolated L2 network segment;� Subnet : an IP address block on a certain network;� Port : an attachment point to a network;� Router : a gateway between subnets;� DHCP : a virtual appliance which gives IP addresses;� Security Group : a set of rules used as filters which implements a

firewall to the cloud platform level.

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How SDN and NFV co-operate

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Advantages e Disadvantages of NFV and SDN

Network cost reductions in hardwareNew business opportunitiesRemoved vendor lock-in problemMulti tenancyAdded flexibility in network functions and dynamismHigh scalabilityPossible loss of performance as the hardware moves fromspecialized to homogeneous� Likely only short term because of expected high innovation in

software

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Case study: Dynamic Service Chaining

� We want to realize a network scenario, at L2 and L3 Levels, whichimplements the NFV and SDN paradigms

� We are refering to a network services provider which offersconnectivity to two users: these contracted different agreements.There are a Residential and a Business Users; the second onerequires a better Qos than the first one.

� The suitable QoS is given by means of virtual network functionsimplementation: they elaborate user’s traffic while the steeringtakes place by means of an adequate programming of the SDNcontroller, applying service chaining mechanisms.

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How does it works

� The edge network containing the two user is built up usingOpenStack; outside its cluster there is the destination edgenetwork which can be reached via Virtual Router

� When a user starts to exchange traffic, initially it will be sent to aDeep Packet Inspector (in order to be classified) and to thedestination host

� After a bit of time traffic will be steered to the related networkfunction in order for the system to give the adequate QoS to eachuser:� WAN Accelerator (implemented by means of Trafficsqueezer) for the

BusUser� Traffic Shaper (realized with Traffic control) for the ResUser

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Topologies: L2 e L3

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L2 Level: topology realization

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L2 Level: Compute node OpenStack

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L2 Level: Network node OpenStack

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Implementative L2 Details

� The source edge network has been built up using the CLI of theOpenStack components (neutron, nova, glance) on Linux terminal

� The destination edge network has been realized in a external hostusing libvirt and the virsh command suite

� The SDN controller which has been programmed and used is theIl controller SDN programmato e utilizzato per la POX (writtenin Python): this allowed an efficient realization of the steeringoperations on br-int and br3� We implemented also some rules for eliminate problems like the ARP

Storming which affects the L2 scenario� The generated traffics of the two VMs have been realized using

the iperf tool, in the UDP mode

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L2 Measures

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L3 Level: topology realization

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Conclusions

� Experimental results have shown how an network approch like this(NFV, SDN, Cloud) can really rebuild the Telco area

� It really gives new possibilities to the network providers to createand manage new market offers with competitive prices, for theproviders themself and for the end-users; the easyprogrammability allows the provider to copy, migrate, destroy andmodificate network functions dynamically implemented

� Future Developments:� Use of the context-aware concept, for a greater involvement of the

SDN paradigm� Other steering experiments with different topologies types, also in

multi-tenant enviroment

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Thanks for the attention!

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Dynamic composition of virtual network functions in a cloud environment

Engineering

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