Dynamic composition of virtual network functions in a cloud environment

Alma Mater Studiorum - Universit`a di Bologna
Dynamic composition of virtual network functions in cloud
enviroments
Supervisor
Prof. Eng. Walter Cerroni
Assistant Supervisors
Eng. 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 edge
networks
In this kind of scenario, it will most likely take place the Cloud
Computing paradigm where network resources are oﬀered from a
provider to a client as a service in a way which is similar to
electricity, 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 to
origin of NFV:
The original Internet paradigm is focused on packet forwarding
based on IP addresses, but in current IP networks packets are
processed 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: the
proposal is to virtualize network functions on general purpose
hardware, simplifying middle-boxes
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Software Defined Networking (SDN)
All those approaches require a certain dinamicity and flexibility at
traffic management level:
SDN: it’s a new approach to computer networking that allows
network administrators to manage network services through
abstraction of low-level functionality, standardised by Berkeley
and 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 and
network services
The OpenFlow protocol lets to communicate network plane with
the data plane: it enables remote controllers to determine the
path 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 physical
machines which contains some servers that will be offered as a
service to a client, in according to the IaaS
(Infrastructure-as-a-Service) paradigm
A user can create a virtual network infrastructure (VNI) composed
of instances (implemented as virtual machines) and networks
appliances (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 in
a 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 hardware
New business opportunities
Removed vendor lock-in problem
Multi tenancy
Added ﬂexibility in network functions and dynamism
High scalability
Possible loss of performance as the hardware moves from
specialized 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, which
implements the NFV and SDN paradigms
We are refering to a network services provider which offers
connectivity to two users: these contracted different agreements.
There are a Residential and a Business Users; the second one
requires a better Qos than the first one.
The suitable QoS is given by means of virtual network functions
implementation: they elaborate user’s traffic while the steering
takes place by means of an adequate programming of the SDN
controller, applying service chaining mechanisms.
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How does it works
The edge network containing the two user is built up using
OpenStack; outside its cluster there is the destination edge
network which can be reached via Virtual Router
When a user starts to exchange traffic, initially it will be sent to a
Deep Packet Inspector (in order to be classified) and to the
destination host
After a bit of time traffic will be steered to the related network
function in order for the system to give the adequate QoS to each
user:
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 the
OpenStack components (neutron, nova, glance) on Linux terminal
The destination edge network has been realized in a external host
using libvirt and the virsh command suite
The SDN controller which has been programmed and used is the
Il controller SDN programmato e utilizzato per la POX (written
in Python): this allowed an efficient realization of the steering
operations 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 create
and manage new market offers with competitive prices, for the
providers themself and for the end-users; the easy
programmability allows the provider to copy, migrate, destroy and
modificate 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

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