CloudStack and SDN
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CloudStack and SDN

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Software Defined Networking is seeing a lot of momentum these days. With server virtualization solving the virtual machines problem, and large scale object storage solving the distributed storage......

Software Defined Networking is seeing a lot of momentum these days. With server virtualization solving the virtual machines problem, and large scale object storage solving the distributed storage challenge, SDN is seen as key in virtual networking.
In this talk we don't try to define SDN but rather dive straight into what in our opinion is the core enabled of SDN: the virtual switch OVS.

OVS can help manage VLAN for guest network isolation, it can re-route any traffic at L2-L4 by keeping forwarding tables controlled by a remote controller (Openfow controller). We show these few OVS capabilities and highlight how they are used in CloudStack and Xen.

Xen Summit presentation of CloudStack and Software Defined Networks. OpenVswitch is the default bridge in Xen and supported in XenServer and Xen Cloud Platform

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  • Related VMs are placed into security groups: for example, web vms are placed in the web security group and the db vms are in the DB security group. By default all ingress traffic to the vm is dropped. To allow web vms to communicate to DB vms, the cloud user calls an api to allow access on the database’s tcp port.
  • Each pod has a different subnet. When a VM is started in a pod, it acquires a free ip in that pod’s subnet. Different tenants can land up in the same pod and hence share the same L2 subnet. Because security groups deny all by default, each VM needs a host-based firewall (embedded in the hypervisor dom0) to enforce this. This also prevents stuff like DHCP and ARP snooping. To prevent attacks, multicast and broadcast are blocked by the firewall
  • As a tenant starts more vms, the vms can land in different pods. The cloud user cannot make any assumptions about L2 connectivity between their vms.
  • As vms get created and destroyed, CloudStack has to ensure the configuration of the host-based firewalls (iptables) is consistent with the security group rules programmed by the cloud user
  • 40,000 hypervisors in a data center x 25 vms / hypervisor = 1 million firewalls to be orchestrated by CloudStack
  • An ipset is a kernel datastructure that can match an ip very efficiently against a large set of ips. For example, using a tree structure, an ip address can be quickly tested for containment. The ipset is supplied to the iptables rule leading to a single iptable rule.

Transcript

  • 1. Xen*, SDN andApache Cloudstack Sebastien Goasguen,Apache CloudStack Citrix EMEA August 28th 2012 Xen Summit
  • 2. Outline• A bit about CloudStack• A bit about SDN• A bit about OpenVswitch• Some bits about “SDN” in CloudStack• Slides are on slideshare for download:http://www.slideshare.net/sebastiengoasguen/ cloudstack-and-sdn
  • 3. Apache CloudStack• IaaS solution to build a • Java application private/public cloud • Ant build but moving to• Hypervisor agnostic: maven (via new – Xen, XS, XCP contributor) – KVM – VMware• Object store support • First Apache release 4.0 – Swift coming Sept 26th – Upcoming support from Caringo• EC2/S3 compatibility
  • 4. Participating in CloudStack• Apache incubator project• http://www.cloudstack.org• #cloudstack on irc.freenode.net• @CloudStack on Twitter• http://cloudstack.org/discuss/mailing-lists.html Welcoming contributions and feedback, Join the fun !
  • 5. A Very Flexible IaaS PlatformCompute HypervisorStorage Block & Object Primary Storage Secondary StorageNetwork Network & Network Services http://www.slideshare.net/cloudstack/cloudstack-architecture
  • 6. NaaS ?• “Cloud Servers” – On-demand, Elastic, Measured server provisioning• Cloud Storage – Scalable/fault tolerant storage with object stores• Cloud Networks – How to do on-demand, elastic, measured networking provisioning ? – How to program the network ?
  • 7. A very extensive API • CloudStack orchestrates your network: – Provisioning – Configuration – Updates • For multi-tenants isolation • Using hardware and software devices • At scale: O(10^4) Hyp, O(10^5) VMs…
  • 8. Software Defined Networking• Enable innovation, experimentation, optimization and customization of networks• Move control of the network to software. i.e Programmable network• Virtualize the network• Vendor-agnostic, standard protocol for control: OpenFlow
  • 9. OpenFlow • Leading SDN protocol • Decouples control and data plane by giving a controller the ability to install flow rules on switches. • Hardware or software• Google achieved 95% switches can use utilization of WAN OpenFlow backbone by using SDN • Spec driven by ONF
  • 10. OpenFlow• OpenFlow rules can drop, rewrite, forward packets Rule Action Stats Packet + byte counters 1. Forward packet to port(s) 2. Encapsulate and forward to controller 3. Drop packet 4. Send to normal processing pipeline Switch MAC MAC Eth VLAN IP IP IP TCP TCP Port src dst type ID Src Dst Prot sport dport Diagram Src: http://www.openflow.org/wp/documents/August 28, 2012 10
  • 11. OF Controllers • Several controllers out there (NOX, POX,Trema…) • Floodlight from Big Switch. Apache license
  • 12. OpenVSwitch • “Open vSwitch is a production quality, multilayer virtual switch licensed under the open source Apache 2.0 license. It is designed to enable the massive network automation through programmatic extension…”
  • 13. OpenVSwitch • Default bridge in XenServer and XCP • Supported in Xen but not integrated in toolstack • Enables: – VLAN tagging – Rate limiting – GRE tunnels – OpenFlow controller – … • High Performance ( http://networkheresy.com/category/
  • 14. e.g OVS rate limiting• Can enforce QoS with rate limiting controls• ovs-vsctl set Interface tap0 ingress_policing_rate=1000• ovs-vsctl set Interface tap0 ingress_policing_burst=100
  • 15. e.g OVS VLAN tagging • ovs-vsctl add-br br0 • ovs-vsctl add-port br0 eth0 • ovs-vsctl add-port br0 tap0 tag=1 • ovs-vsctl add-port br0 tap1 tag=2 • Complement on host2…
  • 16. e.g OVS and GRE tunnels• No Cookbook on OVS page• ovs-vsctl add-port br1 gre1 -- set interface gre1 type=gre options:remote_ip=192.168.1.152
  • 17. OVS and Openflow• Point OVS switches to an OF controller: $ovs_vsctl set-controller br0 tcp 192.168.1.33:6633• Install rules on switch –Proactively (before any packet flows) –Reactively (unknown packets forwarded to controller, who pushes flow mod on switch, then operates at line rate)• Can do SDN with OpenFLOW but also with straight up OVS and managing mappings/rules in CloudStack db.
  • 18. OpenNebula • Supports VLAN tagging and rate limiting through “hooks” that call ovs_vsctl • Scripts executed on an hypervisor before a VM is launched • Potentially also executed after VM shutdown for cleanup • Also supports OpenFlow
  • 19. CloudStack Nicira Support • https://cwiki.apache.or g/confluence/display/CL OUDSTACK/Feature+Nic ira+NVP+integration • By Hugo Trippaers, Schuberg Philis
  • 20. API key to customization of the network • You dream it, CloudStack orchestrates it 
  • 21. Terminology Zone: Availability zone, aka Regions. Could be worldwide. Different data centers Pods: Racks or aisles in a data center Clusters: Group of machines with a common type of Hypervisor Host: A Single server Primary Storage: Shared storage across a cluster Secondary Storage: Shared storage in a single Zone
  • 22. Physical Network Operations Users Admin and Cloud API CloudStack Mgmt Server Cluster Router MySQL Load Balancer Availability Zone L3 Core Switch Access LayerSwitches … Secondary Servers Storage … … … … Pod 1 Pod 2 Pod 3 Pod NSlide from Chiradeep Vittal, http://www.slideshare.net/cloudstack/cloudstack-networking
  • 23. Layer-2 Guest Virtual Network 1 VLAN per guest network CS Virtual Router provides Network Services External Devices provide Network Services Network Hardware exposing API can be controlled Guest Virtual Network 10.1.1.1/8 Guest Virtual Network 10.1.1.1/8 VLAN 100 VLAN 100Public PublicNetwork/Inter Network/Internet net Guest Guest Private IP VM 1 Public IP 10.1.1.1 VM 1 10.1.1.1 10.1.1.111 Gateway 65.37.141.11 JuniperPublic IP 1 SRX address65.37.141.11 CS Firewall 10.1.1.1 Guest Guest Virtual 10.1.1.3 VM 2 10.1.1.3 VM 2 Router Public IP Private IP DHCP, DNS 65.37.141. 10.1.1.112 NetScaler NAT 112 Guest Load Guest Load Balancing 10.1.1.4 VM 3 Blancer 10.1.1.4 VM 3 VPN Guest Guest 10.1.1.5 VM 4 10.1.1.5 VM 4 CS DHCP, Virtual Router DNSSlide from Chiradeep Vittal, http://www.slideshare.net/cloudstack/cloudstack-networking
  • 24. Opportunity for Xen• Opportunity to create highly specialized networking services appliances using – OpenMirage VMs – HalVM• See talks in Monday’s session
  • 25. Networking challenges in a private Cloud• Multi-tenants on hypervisors => isolation between guest networks• VLANs in the datacenter is hard and limit at 4096 VLANs.• Hardware switches may not do it very well or have a lower limit
  • 26. Networking trend• Move to software switches• Move to L3 isolation• Use tunnels between OVS (GRE tech preview)• Program the network through API• Encapsulation virtualizes the network, between overlays on overlays on overlays..• L3 on L2 on GRE on L3 on L2…• Then you bring the WAN and you have:• L3 on L2 on GRE on L3 on L2 on GRE on L3 on L2 ….Euhhhh !!!
  • 27. Back of the enveloppe• ~10,000 hypervisors in your data center• ~100,000 VMs – x10 or x100 if you use HalVM or Openmirage.org • (10,000*9,999)/2 tunnels for a full mesh – 50x10^6 tunnels to keep track of ?
  • 28. Slide from Chiradeep Vittal Layer 3 cloud networking Web Web DB DB Web Web VM VM VM VM VM VM Web DB Security Security Group Group Web Web Web Web DB DB VM VM VM VM VM VM … … … Web Web Web Web VM VM VM VMIngress Rule: Allow VMs in Web Security Group access to VMs in DB Security Group on Port 3306
  • 29. L3 isolation with distributed firewalls Tenant 10.1.0.2Public Public IP address 1 VM 1Internet 65.37.141.11 65.37.141.24 65.37.141.36 10.1.0.1 Pod 1 L2 Tenant 10.1.0.3 65.37.141.80 Switch 2 VM 1 Tenant 10.1.0.4 1 VM 2 L3 Core Pod 2 L2 Switch 10.1.8.1 … 10.1.16.1 Load Pod 3 L2 Balancer Switch … Slide from Chiradeep Vittal
  • 30. L3 isolation with distributed firewalls Tenant 10.1.0.2Public Public IP address 1 VM 1Internet 65.37.141.11 65.37.141.24 65.37.141.36 10.1.0.1 Pod 1 L2 Tenant 10.1.0.3 65.37.141.80 Switch 2 VM 1 Tenant 10.1.0.4 1 VM 2 L3 Core Pod 2 L2 Switch 10.1.8.1 … 10.1.16.1 Load Pod 3 L2 Balancer Switch … Tenant 1 VM 3 10.1.16.47 Tenant 10.1.16.85 1 VM 4 Slide from Chiradeep Vittal
  • 31. L3 isolation with distributed firewalls Tenant 10.1.0.2Public Public IP address 1 VM 1Internet 65.37.141.11 65.37.141.24 65.37.141.36 10.1.0.1 Pod 1 L2 Tenant 10.1.0.3 65.37.141.80 Switch 2 VM 1 Tenant 10.1.0.4 1 VM 2 L3 Core Pod 2 L2 Switch 10.1.8.1 … Tenant 10.1.16.12 10.1.16.1 2 VM 2 Load Pod 3 L2 Balancer Switch Tenant 2 VM 3 10.1.16.21 … Tenant 1 VM 3 10.1.16.47 Tenant 10.1.16.85 1 VM 4 Slide from Chiradeep Vittal
  • 32. A Million Firewalls? VM VM VM VM… VM VM VM VM … … … VM VMVM VM … VM VM VM VM VMVM VM VMVM VM VM VM VM VM VM VM VMVM VM VM VM VM… VM VM VM VM … … … VM VMVM VM … VM VM VM VM VMVM VM VM VM VM VM VM VM VM VM VM VM VM VM VM VMVM VM… … VM VM VM VM … … VMVM VM … VM VM VM VM VM VM VM VMVM VM VM VM VM VM VM VM VM VMVM VM VM VM… VM VM VM VM … … … VM VMVM VM … VM VM VM VM VM VM VMVMVM VM VM VM VM VM VM VM VMVM VM VM VM VM… VM VM VM VM … … … VM VMVM VM … VM VM VM VM VM VM VM VMVM VM VMVM VM VM VM VM VM VM… VMVM VM VM … VM VM VM VM … VM VM VM … VM VM … VM … VM VM VM VM VMVM VM VM VM VM VM VM VM VM VM VMVM VM VM VM VM… … VM VM VM VM … … VMVM VM … VM VM VM VM VM VM VM VMVM VM VM VM VM VM VM VM VM VMVM VM VM VM… VM VM VM VM … … … VM VMVM VM … VM VM VM VM VM VM VM VMVM VM VM VM VM VM VM VM VM VM Slide from Chiradeep Vittal
  • 33. Problem:Manage the state of 100s of thousands of firewallsSolution:Well-known software scaling techniques•Message queues•Consistency tradeoffs•Idempotent configuration & retries CloudStack uses •special purpose queues •optimized for large security groups •eventual consistency for rule updates Slide from Chiradeep Vittal
  • 34. Problem:Firewall (iptables) rules explosion on the host firewallSolution:Use ipsets: ipset –N web_sg iptreemap ipset –A web_sg 10.1.16.31 ipset –A web_sg 10.1.16.112 ipset –A web_sg 10.1.189.5 … ipset –A web_sg 10.21.9.77 -A FORWARD –p tcp –m tcp –dport 3060 –m set –match-set web_sg src -j ACCEPT Slide from Chiradeep Vittal
  • 35. Conclusions• Programmable networking is here• Software switches are key enabler to network virtualization• Opens the door for scalable, on-demand, ephemeral networks• OVS is the default switch in Xen, and supported in XenServer and XenCP.• CloudStack implements highly scalable network structures and leverages OVS capabilities
  • 36. Participating in CloudStack• Apache incubator project• http://www.cloudstack.org• #cloudstack on irc.freenode.net• @CloudStack on Twitter• http://cloudstack.org/discuss/mailing-lists.html Welcoming contributions and feedback, Join the fun !