Virtual Software Routers: A Performance and Migration Study

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Frederick Kennedy
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1 Virtual Software Routers: A Performance and Migration Study DFN-Forum 2010 ZdravkoBozakov

2 Network Virtualization Decouple logical and physical network resources Tunnels/virtual links Virtual routers, virtual control/forwarding plane Increased flexibility Deployment of concurrent virtual networks Network architecture evolution through phase-in of new services Network management benefits IPv6 IPvX IPv4 2

Increased flexibility Deployment of concurrent virtual networks Network

3 Network Virtualization: Use-Cases Flexible mapping of resources (N:M) Provide slices of router hardware to virtual network operators Control multiple forwarding engines using a single control plane Separation enables live-migration of logical resources Scheduled router maintenance Load balancing g( (capacity, routing tables, CPU load) Resource consolidation, energy efficiency Research challenge: proprietary systems Closed hardware / source code Limited interoperability 3

of logical resources Scheduled router maintenance Load balancing g( (capacity, routing tables, CPU load) Resource

4 Performance Study: Motivation Can we use commodity hardware for routing? Commercial HW vs. cheap, redundant, off-the-shelf PCs (Google approach) Open software spurs innovation How can we leverage system virtualization platforms for router virtualization and migration? Highly successful deployment in data centers today. Build on several decades of experience Which h router components do we virtualize? it Fully virtual router Virtual control plane Virtual forwarding plane 4

virtualization platforms for router virtualization and migration? Highly successful deployment in data centers today.

5 System Virtualization Architectures Full virtualization Minimal hypervisor layer Unmodified guest operating systems Para-virtualization Guest hosts are virtualization aware Improved performance Container-based virtualization Lightweight (pseudo-) virtual environment Low overhead Trade-off: performance & resource isolation. 5

virtualization aware Improved performance Container-based virtualization

6 Migration Strategies Stop-and-copy Pause VM Transfer memory dump Resume VM Iterative stop-and-copy Enable memory ypage logging g Transfer full memory dump Iteratively transfer dirty memory pages until threshold Stop-and-copy for final memory pages Router migration Migrate control plane Migrate forwarding plane flow entries 6

Iteratively transfer dirty memory pages until threshold Stop-and-copy for final

7 Experimental Setup Tested virtualization platforms: Xen, KVM, OpenVZ 1Gbps, Dell Optiplex PCs, Intel PRO/1000, XORP Independent control network CBR cross-traffic (A B) generated usingnetfpga Virtual machine migration from R1 R2 7

XORP Independent control network CBR cross-traffic (A B)

8 Experimental Setup Metrics Achievable throughput (A B) Round trip times (C D) Migration duration Network downtime VM migration traffic 25 runs per experiment automated using SSHLauncher [1] [1] 8

downtime VM migration traffic 25 runs per experiment

9 Throughput 1500 Byte packets Maximum throughput Linux, Xen, OpenVZ: line rate KVM: ~800 Mbps PCI pass-through: equivalent to Linux performance 9

10 Throughput 64 Byte packets Maximum throughput: Linux: ~300 Mbps Xen: ~100 Mbps OpenVZ: ~100 Mbps KVM: ~50 Mbps Majority of packets dropped at bridge Slightly better results with Intel igbdriver 10

11 Migration Time and Downtime Xen: cross traffic dependent, unreliable for 64B packets KVM: times approximately constant t 11

12 Comparison to Various Systems 12

13 Processing Time of Various Systems 13

14 Conclusion Summary Throughput very low for small packet sizes routed within fully virtualized software routers Lightweight OpenVZnot as efficient as expected Tested Xenversion has stability issues when migrating under high packet load Very low downtimes possible during migration Tested platforms feasible for control plane virtualization & migration Outlook Evaluate Intel virtual device queues Develop HW-supported forwarding plane virtualization Utilize Openflowenabled forwarding hardware 14

downtimes possible during migration Tested platforms feasible for control plane virtualization & migration Outlook Evaluate

15 ThankYou 15

16 Router Migration Live router migration [1] Common substrate Separate control/data planes 1. Establish tunnels for routing message redirection 2. Migrate control plane (iterative copy) 3. Redirect routing messages Remote controlled source data plane Keep target control plane up-to-date Data plane 4. Re-instantiate target data plane (FIB, ACLs) Control plane using data plane hypervisor Parallel data plane operation 5. Asynchronous link migration 6. Disable source router Data plane 16

Redirect routing messages Remote controlled source data plane Keep target control plane up-to-date Data plane 4.

17 Talk Outline Network virtualization overview and use-cases System virtualization ti architectures t and migration approaches Experimental Setup and Measurements results Summary &outlook 17

Network Virtualization

Network Virtualization What is Network Virtualization? Abstraction of the physical network Support for multiple logical networks running on a common shared physical substrate A container of network services