Evaluating the Trade-off between Resilience Design Alternatives in - PowerPoint PPT Presentation

Network Architectures and Services, Georg Carle Faculty of Informatics Technische Universität München, Germany Evaluating the Trade-off between Resilience Design Alternatives in a Virtual Network Environment under Different Network Visibility Conditions Juan Pablo Alanis Barrera Nokia Siemens Networks Işıl Burcu Barla Stephan M. Günther 14 November, 2012

Thesis Objective  Design an indicator to determine at which layer the resilience provisioning should be carried out.  Evaluate the performance of the metric under different visibility conditions.  Find out the trade off between the resilience design models. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 2

Agenda  Introduction to Network Virtualization  Network Virtualization business roles  Resilience Models  Network Robustness indicators  Algebraic Connectivity  Methodology  “Hiding Bandwidth” metric  “QoS Differentiation” metric  Virtual Network Simulator tool  Example of visibility conditions  Result Analysis and Evaluation  Conclusion Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 3

Introduction to Network Virtualization  What is Network Virtualization?  “Technique for isolating computational and network resources through virtualization to allocate them to a logical (virtual) network for accommodating multiple independent virtual networks.” [1]  Benefits  Operating isolated network slices on diverse physical infrastructures.  Enabling diverse network architectures to operate on shared physical substrates.  Providing flexibility of adding and managing service- tailored networks. [1] Akiro Nakao, “Network Virtualization as Foundation for Enabling New Network Architectures and Applications”, IEICE TRANS. COMMUN., VOL.E93-B, NO.3, MARCH 2010. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 4

Network Virtualization Business Roles Virtual node Virtual Network Operator (VNO) VNet • Requests a virtual topology Virtual 2 VNO1 • Operates the virtual topology link • Provides connectivity VNet 1 Mappin g PIP 2 Physical Infrastructure Provider PIP 1 (PIP) • Possesses physical resources • Virtualizes physical resources • Lease resources to VNO’s Physical link Physical node Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 5

Resilience Models  There are two fundamental resilience models: the PIP-Resilience and the VNO-Resilience.  PIP resilience:  The PIP is on charge of the resilience on the physical infrastructure  Each virtual path is mapped in 2 disjoint physical paths  Ideally, the VNO is unaware of rerouting and failures  VNO resilience:  The VNO is responsible of resilience  The working and protection path have to be physically disjoint  The VNO reroutes the traffic in case of failures. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 6

Network Robustness Indicators  The edge connectivity η (G) of a connected graph G is the smallest number of edges whose removal disconnects G.  The vertex connectivity ν (G) of a connected graph G is the minimum number of vertices whose removal disconnects G.  The algebraic connectivity λ2 (G) is defined as the second smallest eigenvalue from the Laplacian Matrix. E D A B C = = 2 = 2 1.38 Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 7

Algebraic Connectivity  The algebraic connectivity λ2 (G) is defined as the second smallest eigenvalue from the Laplacian Matrix L(G) . Where G is graph G=(V,E).  L(G) is calculated as L = D - L.  λ2 (G) is a non-decreasing function of the number of links with the same set of nodes. 2 0 0 0 0 0 -1 0 0 -1 0 2 0 0 0 -1 0 -1 0 0 D = 0 0 2 0 0 A = 0 -1 0 -1 0 0 0 0 2 0 0 0 -1 0 -1 0 0 0 0 2 -1 0 0 -1 0 Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 8

Methodology  There is a fixed number of PIPs that provide the infrastructure to the VNO.  Each PIP has the exact same set of nodes.  The set of edges between PIPs may be different.  In each PIP physical substrate, a maximum initial load is set, that ranges from 40% to 60%.  “ Hiding Bandwidth ” metric  The hiding factor h is the percentage of the link bandwidth that is hidden by the PIP to the VNO due to resilience purposes.  The value of h ranges from 40% to 60% of the total link bandwidth. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 9

Methodology  “ Hiding Bandwidth ” cont’d  The set of visible resources to the VNO is defined as  For this metric a threshold is set to measure the effect of the hidden bandwidth.  The gain of the metric is calculated as follows: Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 10

Methodology  “ QoS Differentiation ” metric  Three client memberships are defined C = {bronze, silver, gold}.  Depending on the VNO membership and the link load, the visibility of the link is modified to the VNO:  If a link load is less than 30%, it is shown to all clients.  If the link load is larger than 30% and less than 70%, it is only shown to silver and gold clients.  If a link load is larger than 70%, it is only shown to gold clients.  The gain of the metric is calculated as follows: Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 11

Methodology  Virtual Network Simulator tool  In order to obtain a benchmark of the metrics’ performance, the metric gain is compared against the output of the Resilience designs of the Virtual Network Simulator tool presented in [2].  The VNet resilience designs are modeled as MILPs with an objective function of delay minimization.  The VNet delay is the sum of the observed delay of the services running on the VNet.  The simulator also provides the cost of the VNet, which is defined as follows: VNet cost = (fixed + variable) for VLinks + (fixed + variable) for VNodes [2] I. B. Barla, D. A. Schupke and G. Carle , “Resilient Virtual Network Design for End-To-End Cloud Services”, IFIP Networking 2012, Prague, May 2012. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 12

Example of Visibility Conditions  Scenario: service differentiation  Visibility conditions:  Link load < 30%: visible to all clients  Link load > 30% & < 70%: only visible to silver and gold clients  Link load > 70%: only visible to gold clients  VNO 1 membership: bronze A C VNO1 VNet 1 B  PIP1 C-D link load is 50% PIP 1  The load of links from PIP2 C C-D & A-C are 60% A =>NO SURVIVABLE MAPPING IN Overlapping PIP‘s B D EACH PIP ALONE. PIP 2 C BASED ON THIS VISIBILITY CONDITIONS A SOLUTION: Acquire resources for both PIP‘s B D Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 13

Result Analysis and Evaluation  Different network sets used in the simulations Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 14

Result Analysis and Evaluation  This work uses the following as a proof of concept:  1 PIP, 1 VNO and no hidden information: the virtual simulator output ratio is equal to 1.  ˆ 1 PIP, 1 VNO and hidden information: the virtual simulator output ratio is less than or equal to 1.  ˆ n PIPs, 1 VNO and no hidden information: the virtual simulator output ratio is higher than or equal to 1.  Network simulator values used for the simulations.  Total capacity on a physical links: uniform of 100 Gbps  Bandwidth amount requested per service demand: uniform for all services.  Setup cost for link and nodes: proportional to the link length. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 15

Results Analysis and Evaluation  Results 7-node sparse set for Hiding Bandwidth metric  Break even point observed several times  Abrupt change of the simulator ratio seen due to the hidden information. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 16

Results Analysis and Evaluation  Results 7-node mesh set for Hiding Bandwidth metric  The hidden bandwidth does not affect in the same proportion in comparison with the 7-node sparse set. Juan Pablo Alanis Evaluating the trade-off btw resilience design alternatives in a VNE under different net. visibility conditions 17