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V. referencesIrrespective of thecurrent trends of virtualization in every aspect of cloud computing and internetprotocols, network virtualization stands unique from the virtualization designspace point of view. As it is necessary to have a virtualized network in orderto set an inter-connection between all other virtual networks, it is alsocrucial to enhance the rapidity of internet and networking that is seeing aslow paced activity because of the huge population of multiuser support system.Most current researchers think that a redesign is a necessity and not a luxury.
NV can take a stand point and leadership in the field of cloud computing topromote innovation, flexibility and heterogeneity. This realization has led tothe rise of innumerable projects across the globe related to NV. Moreover, realizingthe actual extent of NV needs to satisfy the requirements and objectives set byits designated goals. Although ensuring these shall give rise to a flexible andheterogeneous networking environment, attaining these is difficult.IV. conclusionPre-deployment phenomenaincludes the geographical distribution of networking services that is typicallydesignated and assessed in test labs under controlled environment and thesetests are limited to simple topologies and traffic patterns.3.
7 Experimental anddeployment facilityThis concept should reignon the underlying networking technologies as well as on end to end virtualnetworking to provide a wide array of topologies to the users.3.6 HeterogeneityProgrammability of thenetwork elements is crucial to give birth to a flexible and manageable VN.3.5 ProgrammabilityThese should be providedby the NV to prevent any mishaps resilient to faults and attacks.3.4 Isolation, security andprivacyNV should always motivatethe coexistence of multiple networks over the same physical substratum in orderto provide multiple virtual networks for the underlying infrastructure tomanage resources (Addanki et al,.
2017).3.3 Scalability NV should separate SPsfrom InPs to modulate and manage tasks to introduce accountability innetworking3.
2 ManageabilityCrucial for NV in order toprovide SPs stage to use arbitrary topologies3.1 FlexibilityEnabling of multipleanalogous virtual networks to cohabit together has a set goal on a sharedphysical substratum that can be categorized into several smaller objectives. Inorder to bring these to action, each of these designated goals must befulfilled to the brim. These goals helps in providing a guideline in thedesignation of a protocol or an algorithm for virtual networks and can also beused to compare multiple NV schemes3. Design GoalsAn edge Ev in the virtualnetwork spans over one or more connected physical links in the underlyingphysical topology.
2.5 Virtual linkIt can either be a virtualhost or a router all on its own.The former act as a packet source and cannot befound inside the network whereas the virtual router acts in a way similar tothe router in the physical network.
Its main application is to forward packetsin accordance to the protocols generated.2.4 Virtual NodeAnother weightedundirected graph Gv=(Vv, Ev) where Vv is the set of virtual nodes and Ev thevirtual links (Sunay et al,. 2017)2.3 Virtual topology It is designated by aweighted undirect graph Gp = (Vp, Ep), where each node in the network isvertex.
2.2 Physical topologyThis section defines thecommonly used terminologies and notations frequently appearing while describingor referring to the different aspects of a NV architecture.2.1 ConceptsThe basic entity of an NVEis the virtual network or VN and each one of these are made up of and managedby a single SP.
It is nothing else but a collective assembly of virtual nodesconnected together by a set of virtual links forming a virtual topology. Fig. 2(Zhang et al,. 2017) designates twoanalogous virtual networks VN1 and VN2 created by service providers SP1 and SP2respectively. The former composed VN1 on top of the physical resources whichwere managed by two different infrastructure providers InP1 and InP2, providingend to end users U2 and U3. The latter, on the other hand, had a deployment ofVN2 by combining resources from InP1, with a child virtual network from SP1.
End users U1 and U3 have been well connected by VN2.2. ArchitectureThey play an importantrole in the network virtualization economy, acting as mediators between InPs,Sps and end users in the network virtualization marketplace. Sps lease theresources from InPs to create virtual networks of all sort and deployment ofsold services to these virtual networks to interested end users throughbrokers.
The presence of brokers makes it easier for the matching processes ofSPs’ requirements to available resources by accumulating offers from multipleInpS and also helps by allowing end users in selecting desirable services froma wide range of SPs.1.4 BrokerAs far as the network virtualizationis concerned, end users are similar to the end users in the already prevailinginternet, with an exception of multiple virtual user existence from competingSPs that leads to the enabling of choices from a wide range of services. Anyend user may feel free to get connected to a multiple service provider fordifferent services (Jiang et al,.2017).1.3 End userService providers or SPsgive off resources from multiple facilities providers in order to createvirtual network while deploying customized protocols by programming therequisite networking resources to offer end to end services to the end users.Child virtual networks can also be created by an SP by partitioning itsresources.
After that, lease of those child networks can be provided to otherservice providers, thereby taking a practical role of an infrastructuralprovider creating a hierarchy of roles (Fig. 1b) (Kitindi et al,. 2017).1.2 Service ProviderInfrastructure providersor InPs engages and manages the underlying physical network resources in theNVE. They forms the baseline for managing, operating and maintaining thephysical infrastructure and resources through programmable interface todifferent ISPs.
No direct services are provide to the end users. Infrastructureproviders make themselves unique in the way of quality of resources that isprovided, the freedom and tools being imparted to their customers or serviceproviders.1.1 Infrastructure ProviderThe NV model players orinvestors (Fig. 1a) (Kitindi et al,. 2017)varies from those in the traditional networking model. There lies the presenceof two distinctive roles: infrastructureproviders and service providers,represented by a single role; ISP in the conventional model.
Looking from acommercial point of view, this decoupling phenomena reduces high fixed cost ofmaintenance that is a result of sharing capital and operational expendituresacross multiple infrastructure providers. Emphasis should also be put onbusiness roles that do not necessarily join one to one distinct businessentities which means that any business entity can assume multiple roles.1. Reference Business ModelThe pluralist approach definesnetwork virtualization as a crucial part of the diversified internetarchitecture that helps in supporting multiple cohabiting networkingarchitectures from different ISPs that shares a common physical matrix orsupport. These are managed by a multiple infrastructure providers. By thephenomenon of decoupling ISPs from infrastructure providers, NV sets forthflexibility for innovation and change.
This section deals with aconceptualistic approach of the NV architecture in accordance with a referencebusiness model and identifies the main designating factors to materialize thearchitectureIII. network virtualizationenvironment (NVE)Routing Service Providers(RSPs) are introduced as third parties by the “Routing as a Service” (Abdelazizet al,. 2017)in buying virtual linksfrom different ASes connecting a number of virtual routers. Hosts who desire acustomized route may contact with an RSP for a contract establishment, therebysetting up an end to end overlay path along its virtual links corresponding tothe global topology. OverQoS sets a stage for giving ample informationregarding to establish overlay links with certain loss and delay gurantees (Addankiet al,. 2017). Provision of valueadded internet services is achieved by the use of Service Overlay Network (SON)(Kitindi et al,. 2017) and it canpurchase bandwidth of up to certain QoS guarantees from different ISPs in order to construct a logical end to endservice delivery overlay.
The Detour study (Fietz et al,.2016) has shown that the re-routing packets had been found useful in improvingend to end performance via virtual tunneling, in terms of loss, latency andthroughput compared to the direct internet path. The Resilient Overlay Network(RON) (Gross and Davie, 2016; Narten etal,. 2016) project experimentally determined the fact that an overlaynetwork that works on its own networking measurements recovers faster fromfailure with an enhance in latency.The overlay-based Internet IndirectionInfrastructure (i3) (Black et al,.2016) makes it a point to simplify the network services’ deployment andmanagement services by decoupling sending and receiving. In i3, packets arebeen sent from the sources to a logical identifier while the recipient expressinterest in packets that is sent to the identifier.
This level of indirectionenhances flexibility in node mobility and deployment. In all the three cases,routing performance of the internet is wired by an overlay on top of theexisting matrix.Consequentially,deployment of new features and fixes in the internet has long been approachedby the use of overlay network. A wide array overlay networks have been proposedin the recent years to mitigate several diverse issues including performanceinsurance (Low et al,.
2017) andavailability of internet routing (Gross and Davie, 2016), enablingmulticasting, providing QoS guarantees, protection from denial of serviceattacks and for content distribution, file sharing and storage systems (Sunay et al,. 2017).This is a kind of virtualcomputer network creating a virtual topology on top of the physical topology ofanother network. Virtual links connect the nodes in an overlay networkcorresponding to a path that is again connected by multiple physical links inthe underlying network. Overlay network is not governed geographically and suchrestrictions does not follow suit and the involvement is completelyintentional. Because of the fact several participants share their resources tothe network, hence it does not pay overlay a heavy expenditure. Moreover,compared to other networks, they are highly flexible and adaptable.1.
Overlay NetworksMultiple co-inhabiting networks isnot new to the world of cloud computing and internet and has been reportedseveral times earlier in the literatures related to networking. This sectionemphasizes on the most widely accepted incarnation of network virtualization,that is, overlay networks. An overlay network is a kind of virtual network thatfinds use in the application layer in addition to the existence of severalimplementations in the lower layers of the networking protocols. Although weak,it has been widely used to bring in new features and fixes in the internet.II.
historical perspectiveThis report assesses the former andcurrent state of the art technologies in network virtualization whileidentifying its key prospects.Although network visualization hasbeen considered as a stage to assess new architectural advances by the purists,pluralist approaches consider it as a support system for the architectureitself (Blenk et al,. 2016). Theythink that network virtualization has the capability to extenuate thetremendous forces of the current internet and enhance innovative approaches byenabling diverse array of networking architectures to coexist on a sharedmatrix. Policy separation from mechanism is crucial in order to introducediversity in computing field, and such examples have been set by networking virtualizations(Gross and Davie, 2016; Khan et al,. 2016).The role of the ever-changing ISPs has been sub-divided into two categories: infrastructure providers, responsiblefor managing the physical infrastructure, and service providers, responsible for creating virtual networks byaccumulating resources from multiple infrastructure providers thereby offeringend-to-end encryption to the users. This scenario shall encourage thedeployment of multiple cohabiting heterogeneous network architecture unbound bythe inherent restrictions found in the existing internet.
The way of life, our thinking attitudes, modulations towards the societyand virtual proliferation has been widely influenced by the internet and thishas mended the way more smoothly for the development of the human race as awhole. The extent of the internet architectural plethora and influence has beenproven universally over the last three decades by the active support on aplatform of multi-various applications and technologies over which it currentlythrives. But, its popularity has become its toughest enemy. Because of thepresence of a huge population of users and its multi-provider nature, adoptionof any new technology to enhance the existing one will invite strongcompetition among the investors.
Hence, modifications of the internetarchitecture have been limited to only incremental updates without making anyconsiderable changes by the introduction or deployment of new networkingtechnologies (Gross and Davie, 2016).I. INTRODUCTION Keywords:Internet, network virtualization, cloud computing,flexibility, versatility.
Abstract—Networking, currently have facedseveral potholes, due to the presence of multiple investors having differencesof opinions, due to which, changes in the existing internet have now beenrestricted only to incremental apprises; and overall disposition of freshtechnological aspects is completely impossible in this field. In order tomitigate these restrictive issues, network virtualization has been identifiedas the next generation penicillin that shall contribute to the future of cloudcomputing and inter-networking prototype. Network virtualization allows thecoexistence of multiple heterogeneous network architectures on a shared matrix,thereby providing flexibility and versatility with increased security andmanageability. The current report deals with the pros and cons of networkvirtualization in accordance to the set goals, past surveys and state of theart technological advances and also discusses the future challenges and scopesthat require proper identity.