politecnico di torino dipartimento di automatica ed informatica torsec group performance of xen’s...
TRANSCRIPT
Politecnico di Torino
Dipartimento di Automatica ed Informatica
TORSEC Group
Performance of Xen’s Secured Virtual Networks
Emanuele Cesena <[email protected]>Paolo Carlo Pomi <[email protected]>Gianluca Ramunno <[email protected]>Davide Vernizzi <[email protected]>
Outline Introduction Experiments Model Security mechanism Conclusion
Introduction
Motivations Server consolidation
Planning
Model of virtual network Emulation Comparison
Virtualization “Technique for dividing the resources of a computer
into multiple execution environments called virtual machines (VMs)” (A. Singh)
Full virtualization Complete emulation of the underlying hardware Unmodified operating system in the VM
Paravirtualization VM needs a modified OS Best performance, close to native
Virtualization: XEN XEN is a free Virtual Machines Monitor (hypervisor)
x86, Intel Itanium, PowerPC platforms Paravirtualization, full virtualization (hw support) Very low overhead when paravirtualized: average
3-5%
Virtual machines Domain-0: privileged VM
Direct access to hardware Direct interface to the hypervisor
Guest domains
Virtual Network in XEN Network interfaces
Front-end within VM: eth0 Back-end in Domain-0: virtual interface (vif) Connection between netfront and netback
provided by the hypervisor
XEN hypervisor
Domain 0
vif1.0 vif2.0
Guest 1
eth0
Guest 2
eth0
Virtual Network in XEN Virtual Network
Domain-0 manages all the netbacks Bridge as “L2-switch”
XEN hypervisor
Domain 0
vif0.0 vif1.0 vif2.0
peth0
eth0
br0
Dom-0 Guest 1 Guest 2
physicalworld
switch
Virtual Network in XEN Example: Guest 1 sends a packet to Guest 2
packet created within Guest 1 stack copied from FE to BE via page flipping forwarded through the bridge copied from BE to FE, then received by Guest 2
we call this a virtual link
Domain 0
vif1.0 vif2.0
br0
Guest 1
eth0
Guest 2
eth0
Experiments
Experiments HP Compaq dc7700
Intel Core2 Duo 2.13 GHz RAM: 2GB XEN 3.0.4 Linux kernel 2.6.20
10 Virtual Machines (guests) RAM: 128 MB Linux kernel 2.6.20 minimal Debian installation IPerf to test network bandwidth
Experiments: Virtual Network Simple topology
All VMs connected to the same bridge
ClientGuest 1
bridge
ClientGuest 2
ClientGuest 3
ClientGuest 4
ClientGuest 5
ServerGuest 1
ServerGuest 2
ServerGuest 3
ServerGuest 4
ServerGuest 5
Experiments: Virtual Network Simple topology
All VMs connected to the same bridge
Up to 16 virtual links IPerf TCP channels Example with 7 links
ClientGuest 1
bridge
ClientGuest 2
ClientGuest 3
ClientGuest 4
ClientGuest 5
ServerGuest 1
ServerGuest 2
ServerGuest 3
ServerGuest 4
ServerGuest 5
Experiments: tests SMP disabled SMP enabled Static domain scheduling
10 iterations for each experiment 1 minute per link Samples every 5 sec Average value
Experiments: Results NoSMP vs. SMP
Experiments: Results Dynamic scheduling vs Static scheduling
Model
Model: assumptions Simple resource model
Single type of resource Resources completely separated in system and
network Network described by the number of virtual links Bandwidth equally distributed among links
Model M: maximal total bandwidth M – K: minimal total bandwidth (n): total bandwidth
Bandwidth
Network resources
System resources
M
KTotal
resources
n links
Model Model curve vs. experimental data: error less than
2%
Security mechanisms
Security mechanisms Adding security brings
More workload More networking
We focused on increase of number of links (eg. firewalls)
Security mechanisms Number of links increases by a factor s
Depending on topology Depending on the security mechanism
The model allows prediction on the loss of bandwidth
Model application 1/2 Scenario: server consolidation
Computation power available The virtual network must supply the physical interface If the virtual network is well-designed, the virtual
network supports the transaction
Model application 2/2 What happens if we introduce a firewall? Applying the model we can esteem the resulting
bandwidth
Conclusions
Future works Improve the model
Relax assumptions Forecast parameters without experiments
Validate the model Other architecture Other security solutions
Improve Xen D2D communication Optimization
Conclusions We developed a simple (but still effective) model
Explain how virtual network works in Xen Foresee performance of the virtual network
Planning Impact of security solutions
We show the limits of current Xen’s implementation and suggested improvements
Thank you
Any question?