Towards Virtual Routers as a Service

6th GI/ITG KuVS Workshop on “Future Internet”November 22, 2010

Hannover

Zdravko Bozakov

Towards Virtual Routers as a Service

Talk outline Virtualization overview Use case: virtual routers as a service Problem statement Resource allocation algorithm Virtual router location selection In brief

Virtual router architecture Live-migration

Summary and outlook

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Network Virtualization Overview

Virtualization aims to decouple logical and physical network resources and increase network flexibility

Variable mapping of physical and logical entities Slice network hardware for multiple customers Handle multiple network devices using a single control plane

Live-migration of logical routers Load balancing (capacity, routing tables, CPU) Scheduled router maintenance Energy conservation

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Virtual Routers as a Service

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Virtual Routers as a Service

On-demand provision of connectivity over core network Enterprise branch offices Regional providers University campuses

Single virtual router for edge interconnection Reduction of customer management overhead Consolidation of provider resources and transparent remapping

Port relay nodes (PRN) Forward traffic to virtual router (root node)

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Problem Statement

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What we have: Backbone network

Weighted graph G with weights W Link utilization U and capacity C (u/c)

Customer requirements Subset of edge nodes Γ Capacity demand D for

edge nodes γ

What we need: Optimal location of VR root node R Optimal paths from R to Γ satisfying

capacity constraints

W=1

R

Path Selection Algorithm

Trivial case: unlimited backbone capacity For each γ calculate shortest path to R (e.g. Dijkstra)

Does not work for capacity constrained networks

Solution with constraints: flow network theory (successive shortest paths)

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SRC DST

w=0C=1

w=0C=4

Root Node Selection

Optimal location of root node R Minimize the cost S of bandwidth consumed by the VR links V

Root selection using total enumeration Nodes with insufficient resources are pruned (e.g. capacity, CPU, memory)

Example: optimal root node locations with total cost S=4

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Virtual Router Architecture

Root node: hardware accelerated virtual router Control plane virtualization

using standard VMson commodity servers

Programmable data plane using Openflow-enabled switches

Port relay nodes (PRN) Forward packets based

on L2 virtual router addresses along computed paths

Openflow implementation

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Live Router Migration

Virtual router architecture allows live router migration Setup outbound PRN paths for new root node R* Clone forwarding table from old root R and remap physical ports Control plane continuously updates routing tables on R and R* Asynchronously setup inbound paths for R* Tear down old paths and root node

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Watch the demo during the break!

Conclusion and Outlook

Conclusion On-demand connectivity using single logical router instance

reduces management overhead Presented approach allows optimal computation of paths to a router

located within network core Basic root node selection strategy Architecture is capable of live-migration

Outlook Refine path selection algorithm and analyze alternative approaches Optimize root node selection method Detailed evaluation of live-migration performance Implement and evaluate fallback strategies

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