1. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University1 Towards a Framework for Network Control Composition T. S. Eugene Ng Rice University Hong Yan Carnegie Mellon University

2. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University2 Many Network Controls Manage Network State Best effort routing Traffic engineering QoS routing VPN tunneling Packet filtering Planned maintenance Policy based inter-domain routing … Implemented by a variety of –Distributed protocols –Remote configurations How do they coordinate?

3. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University3 Comparing Network Controls to Processes Internet Control PlaneOperating System ProcessesDist. protocols, remote config. Process scheduling? Process synchronization ?? Inter-process communication ??? Memory management ???? vs

4. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University4 “Inter-Process Communication” ISP Y is the preferred egress How to “tell” OSPF this policy? B3 B2B1 C3 C2C1 A2A1 A4 A3 B4 ISP Y ISP Z ISP X Overload semantics of OSPF link weight Prone to policy violations –Traffic engineering, link failure, etc

5. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University5 “Process Scheduling” A packet filter needs to be placed on the flow path OSPF re-routes when network changes B3 B2B1 C3 C2C1 A2A1 A4 A3 B4 ISP Y ISP Z ISP X Who “schedules” the packet filter control to run after routing changes?

6. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University6 “Process Synchronization” Want to perform planned maintenance on C1 How to re-config network in a systematic manner? How to ensure re- config is completed before taking down C1? B3 B2B1 C3 C2C1 A2A1 A4 A3 B4 ISP Y ISP Z ISP X QoS Routed Traffic

7. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University7 “Memory Management” Hardware tables shared by all network controls What does each network control see? –All table space? –Only free table space? How to share limited physical space? Virtual table abstraction? Paging? Packet filterAction Spec 1Forward Spec 2Drop Spec 3MPLS Spec 4Tunnel

8. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University8 Operating Platform Approach Re-factor existing nuts and bolts network controls into simple control applications Applications are not distributed protocols Run control applications on operating platform to achieve control objectives Distributed nature of network control handled by underlying system

9. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University9 4D-like Architecture Network Control Applications Node 1 Node 2Node 3 Meta Management System Operating Platform

10. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University10 Operating Platform Services Network and node abstractions –Topology, hardware tables, link characteristics, load, etc Interfaces for writing network state Control coordination –Inter-process communication –Synchronization –Scheduling Resource management –Coordinated sharing of hardware resources Network protection –Prevent exceeding hardware resource limits –Link bandwidth, hardware tables, etc

11. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University11 Operating Platform Network View Virtualization QoS Routing Inter-Domain Routing Policy Shortest Path Routing Network Maintenance Meta Management Interface B3 B2B1 C3 C2C1 A2A1 A4 A3 B4 ISP Y ISP Z ISP X

12. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University12 Potential Benefits Remove implicit dependencies between controls Prevent unintended side-effects of ad hoc control composition Network control re-configurations are triggered systematically Protect network from faulty network controls A better environment for innovation and evolution

13. T. S. Eugene Ngeugeneng at cs.rice.edu Rice University13 Summary Ad hoc network control composition leads to unwanted complexity and fragile systems It is time to move towards a more principled framework analogous to an operating system Challeges: Develop abstractions and services for a network control platform –Network abstractions and interfaces –Inter-process communication –Scheduling –Synchronization –Resource management –Protection