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![What's SDN? And why?
●
Software Defined Networking
– Making network programmable
– http://www.opennetsummit.org/why-sdn.html
●
SDN is a disruptive technology that is making
networks programmable by ordinary programmers
using ordinary software running on ordinary
operating systems in ordinary servers. With SDN,
the introduction of new features becomes less
manual, less prone to error, and faster to
implement.
– [Paraphrased from the HotSDN ‘13 Solicitaion]
●
Software Defined Networking (SDN) is a refactoring
of the relationship between network devices and the
software that controls them.
● Motivations behind SDN
– Academic research
● Allow researchers to program/modify
switches freely
– Industry technology trends
● Virtualization/cloud technology
● Network is behind those technology
progress
● Networkig virtualization/automation](https://image.slidesharecdn.com/ryu-sdn-framework-upload-130914010856-phpapp01/75/Ryu-sdn-framework-5-2048.jpg)
Uploaded byIsaku Yamahata
Ryu sdn framework
The document presents an overview of Ryu, a component-based software-defined networking (SDN) framework primarily developed in Python. It highlights Ryu's architecture, event-driven features, and integration capabilities with OpenStack, while discussing the motivations behind SDN and its underlying principles. Additionally, it covers Ryu's development process, supported protocols, and its ease of use in networking applications.
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Ryu sdn framework
- 1. Ryu: SDN frameworkand Python experience Isaku Yamahata <yamahata@private.email.ne.jp> <isaku.yamahata@gmail.com> Pycon APAC 2013, September 14
- 2. Agenda ● Introduction ● Ryu:SDN framework ● Ryu Internals – Openstack support ● Ryu development ● Python experience through Ryu This presentation represents my personal view/opinion. Not Ryu project nor any companies.
- 3. Who am I? ●My background is OS/virtualization/cloud – Not network guy ● Programming language – C/C++/assembler ● Projects I've contributed – Linux – Virtualization ● Qemu, KVM, Xen – OpenStack ● Nova, neutron(formarly quantum) Ryu plugin – Open vSwitch ● My python experience had begun with OpenStack and Ryu
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- 5. What's SDN? Andwhy? ● Software Defined Networking – Making network programmable – http://www.opennetsummit.org/why-sdn.html ● SDN is a disruptive technology that is making networks programmable by ordinary programmers using ordinary software running on ordinary operating systems in ordinary servers. With SDN, the introduction of new features becomes less manual, less prone to error, and faster to implement. – [Paraphrased from the HotSDN ‘13 Solicitaion] ● Software Defined Networking (SDN) is a refactoring of the relationship between network devices and the software that controls them. ● Motivations behind SDN – Academic research ● Allow researchers to program/modify switches freely – Industry technology trends ● Virtualization/cloud technology ● Network is behind those technology progress ● Networkig virtualization/automation
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- 8. Openflow datapath(hardware) controlpath(software) datapath(hardware) controlpath(software) openflow Openflow controller Openflowprotocol(tcp/ssl) Ethernet switch Openflow ethernet switch ● protocol to control switches
- 9. Flow table andmatch/action Openflow controller Flow table MAC src MAC dst IP src IP dst TCP src TCP dst ... action Packet in event When entry miss * * * * * 80 output port N port PacketportPacket Packet match Action
- 10. Ryu, a component-based software-definednetworking framework
- 11. What's Ryu? 流 龍 Flow OrientalDragion, A god of water Manages flow control to enable intelligent networking http://ja.wikipedia.org/wiki/%E8%B5%A4%E7%9B%AE%E5%9B%9B%E5%8D%81%E5%85%AB%E6%BB%9D
- 12. What's Ryu? ● acomponent-based software-defined networking framework ● License: Apache 2.0 ● Fully written in Python ● Supports various protocols for managing network devices – OpenFlow, Netconf, OF-config, SNMP etc. ● Official site http://osrg.github.io/ryu/ ● MLhttps://lists.sourceforge.net/lists/listinfo/ryu-devel ● Download https://github.com/osrg/ryu ● Documentation http://ryu.readthedocs.org/en/latest/ ● Wiki https://github.com/osrg/ryu/wiki
- 13. Supported features/protocols ● Openflowprotoocol – OF-wire: 1.0,1.2, 1.3, Nicira extension – OF-config 1.1 ● Non-openflow protocols – Netconf, OVSDB, netflow, sflow, VRRP, SNMP ● Snmp: Enterprise OID: 41786 – Ryu can configure Open vSwitch directly without ovs-vsctl, ovsdb-client Some features are under development. The patches can be found on ML archive. ● RyuApp, library – Packet library – STP, LACP – Sample apps, etc... – Conversion from/to JSON representation from/to OF – RPC to communicate/control Ryu ● Integration with other project – OpenStack – HA with Zookeeper – IDS(Intrusion Detection System) with snort
- 14. OF/firewall/router REST API ●OF REST (ofctl_reset) – Insert/delete openflow rule ● Firewall (rest_firewall) – Configure firewall – https://github.com/osrg/ryu/wiki/Third-Party-Tools,-Etc. ● Router(rest_router) – Configure router Ryu REST OF REST API add a flow entry POST http://example.org/stats/flownetry/add delete flow entries DELETE http://example.org/stats/flowentry/delete get flow stats GET http://example.org/stats/flow/{dpid} allow drop firewall OF switch Ryu REST OF switch router
- 15. Topology Viewer ● Discovertopology by LLDP and show topology/flows dynamically
- 16. HA support ● Centralizedcontroller is single pointer of failure(SPOF) ● Ryu + Zookeeper can be used to address SPOF Ryu Ryu zookeeper OF switch master slave failover
- 17. IDS support ● Snortintegration https://github.com/osrg/ryu/wiki/Snort-Integration Ryu OF switch Sort Control app IDS(snort) 1. L1-L4 matching 2. send patcket to IDS 3. alert4. take actions e.g. loggingt
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- 19. Ryu implementation ● Quitenormal python program from the point of implementation view – It doesn't use any special tricks ● Event driven – Event source/dispatcher/sink – Core(= Event dispatcher) is very small – It is so generic that Ryu can be used without OpenFlow ● Component based – Event source/sink are created as components ● Even OpenFlow related codes are so – Message passing via events, not directly communite.
- 20. Ryu architecture ● Followsstandard SDN architecture OpenFlow switch OpenFlow switch Network device SDN apps Well defined API (REST, RPC...) Open protocols (OpenFlow, OF-config, NETConfig, OVSDB...) SDN apps SDN apps Ryu SDN framework OpenFlow Parser/serializer Event dispatcher Ryu built-in app (tenant isolation, Topology discovery, firewall ) Ryu App libraries Protocol support (OVSDB, VRRP, ...) Ryu App... operator openstack User app Control layer Application layer
- 21. Aio/thread ● Uses eventlet –Like OpenStack – gevent was used before – switched to eventlet for pypy ● twisted was not adopted for simplicity ● eventlet(or gevent) is cooperative threading, so some cautions are needed – This is different from preemptive threading like pthread
- 22. Event Dispatcher ● classAppManager and class RyuApp ● The guts of Ryu ● Decouples event sources/sinks – Event sources generate whatever events – Event sinks register handlers dynamically ● Dispatches events based on class of events – To event sinks that want class of events – Class is a first class object in Python ● knows which methods are interested in which event by methods attributes – Methods are also first class object in Python RyuAppRyuApp queue BRICKS Event Determin which RyuApp to deliver Based on class of event dispatch Events are read only because It is shared with many RyuApps Event sink Event dispatcher RyuAppRyuApp queue RyuAppRyuApp queueEvent source EventEvent source
- 23. Event source/sink ● source –Call methods of the event dispatcher to generate events ● sink – Subclass of class RyuApp ● Event dispatcher knows which methods are interested in which events – Event handlers are invoked in its own thread context of each RyuApp – To avoid race condition – Direct queuing is also possible RyuApp queue Event thread Consuming events Event
- 24. Event request/reply ● request/replymessaging between RyuApps for easy programming RyuApp Event thread RyuAppevent queue RyuApp Event thread RyuApp event queue reply queue reply queue request event reply event 1. queue request event 3. process request 4. queue back result 5. wake up waiting event thread If necessary 2. wait for reply if synchronous
- 25. OpenFlow parser andits event ● Only controller part is supported ● OF events are created automatically on startup – Introspection is used ● “Where EventOFPxxx is defined?” is FAQ ofproto_v1_N_parser OFPxxx EventOFPxxx ofp_event
- 26. Connection to OpenFlowswitch ● class OpenFlowController, class Datapath ● Receiving loop and sending loop OpenFlow switch Receiving thread Generates OFPEvents Sending thread Serialize and send OF packets Send queue EventOFP message Ryu Datapath RyuAppRyuApp queue Event sink
- 27.
- 28. OpenStack Component ● Composedof Many component ● Neutron – Plugin architecture – Able to support many network technology service Openstack project compute nova storage swift(object) glance(image) cinder(block) identity keystone network neutron ... ...
- 29. Ryu Plugin forNeutron ● L2 isolation ● Multi tenant w/o or w/ VLAN – Mac address based – VLAN – GRE tunnel
- 30. Overview of Ryuplugin Compute-node Vif driver Create OVS port Ryu agent OVS OVS initialization OVS Ryu agent OVS initialization L3 agent Neutron Node Neutron DB (Network ID, key) Ryu server (Network ID, key) Neutron API Ryu node r Ryu REST OpenFlow & OVSDB Neutron server Ryu plugin Network node
- 31. OpenStack L2 isolation:logical view VM VM VM VM VM VM Tenant X Tenant Y
- 32. OpenStack L2 isolation:physical view Compute Node Compute Node Compute /network OVS OVS Tenant X VM Tenant Y VM Tenant X VM Tenant Y VM Tenant X VM Tenant Y VM Tenant => GRE key GRE tunnel OpenFlow Tenant X GRE key = M Tenant Y GRE key = N L2 over L3 with GRE tunnel - Able to span over network segments (l2 segment can over multi data centers) - can coexists with Conventional network technology Set GRE key Deliver packets based on GRE key En/de-cupsel packet Into/from GRE packet Ryu nw-gw nw-gw OVS
- 33. Table 0 Table1 Table 2 Src table Tunnel out Local out VM port match action in_port src mac set_tunnel goto table 1 in_port drop match action tunnel_id dst mac output(tunnel) goto table 2 match action tunnel_id dst mac output(vm) tunnel_id goto table 2 tunnel_id drop Tunnel port in_port tunnel_id goto table 2 in_port drop OVS VM1 VM2 GRE tunnel tunnel port VM port In port Flow Table Usage Nicira extension is used for GRE tunnel
- 34. GRE tunneling withOpenStack ● Composed of several RyuApps ● Network tenant creation – Assign GRE key – Create gateway ● Guest VM instance creation – Create port ● Tenant ↔ key ↔ port relationship – Set flow to the VM port ● Tunnel port management – Create/delete tunnel port ● Track physical compute node – Set flow to the tunnel port rest_quantum gre_tunnel tunnel_port_updater quantum_adapter REST OVS ovsdbOpenFlow Neutron Ryu quantum: former name of neutron project
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- 36. Development process ● Opendevelopment ● Linux style ● Discuss on Mailing List openly ● Send/review patches on Mailing List – git format-patch – git send-patch – No pull request on github ● Evolution – Ryu has evoleved from very small program http://dir.gmane.org/gmane.network.ryu.devel
- 37.
- 38. Python ● Good things – Easy/fastto learn/use – Many useful features ● Dynamic language, first class everything, decorator, introspection... – Especially introspection is very useful – Decorator is handy – Many useful libraries ● Bad things – Hard to debug ● debugger(pdb) is unstable ● Debugger isn't compatible with eventlet – Magic attributes(__xxx___) – Many similar libraries: which to use?
- 39. AIO libraries ● Gevent→ Eventlet ● In general, monky-patching is ugly hack and very fragile ● Monkey patching of gevent/eventlet works stably ● Hit some issues and patches are proposed. ● epoll is removed by monkey patching
- 40. Threading ● eventlet(or gevent)is cooperative threading – Needs special care for protection ● Starvation ● Thread scheduling – Different from native threading like pthread ● Synchronization primitives ● Hard to debug – When debugger(pdb) tries to stop, the thread is switched to other thread ● Need to consider – Native vs green – Giant Interpreter Lock – What context to deliver events?
- 41. Performance ● Gevent performsslightly better than eventlet – But it's very slight. – Needs other approach for more performance boost ● Pypy – Needs patch for eventlet ● Mulit process?
- 42. Network programming ● ForIGMP with VRRP ● Needs to read Cpython code or C-module code – Much better than unsupported, though
- 43.