T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
1
Towards a Framework forNetwork Control Composition
T. S. Eugene Ng
Rice University
Hong Yan
Carnegie Mellon University
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
2
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?
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
3
Comparing Network Controls to Processes
Internet Control Plane
Operating System
ProcessesDist. protocols, remote config.
Process scheduling?
Process synchronization??
Inter-process communication???
Memory management????
vs
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
4
“Inter-Process Communication”
•ISP Y is thepreferred egress
•How to “tell” OSPFthis policy?
B3
B2
B1
C3
C2
C1
A2
A1
A4
A3
B4
ISP Y
ISP Z
ISP X
•Overload semanticsof OSPF link weight
•Prone to policyviolations
–Traffic engineering,link failure, etc
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
5
“Process Scheduling”
•A packet filterneeds to beplaced on theflow path
•OSPF re-routeswhen networkchanges
B3
B2
B1
C3
C2
C1
A2
A1
A4
A3
B4
ISP Y
ISP Z
ISP X
•Who “schedules”the packet filtercontrol to runafter routingchanges?
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
6
“Process Synchronization”
•Want to performplannedmaintenance on C1
•How to re-confignetwork in asystematic manner?
•How to ensure re-config is completedbefore taking downC1?
B3
B2
B1
C3
C2
C1
A2
A1
A4
A3
B4
ISP Y
ISP Z
ISP X
QoS Routed
Traffic
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
7
“Memory Management”
•Hardware tables shared by allnetwork controls
•What does each networkcontrol see?
–All table space?
–Only free table space?
•How to share limited physicalspace?
•Virtual table abstraction?Paging?
Packet filter
Action
Spec 1
Forward
Spec 2
Drop
Spec 3
MPLS
Spec 4
Tunnel
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
8
Operating Platform Approach
•Re-factor existing nuts and bolts network controls intosimple control applications
•Applications are not distributed protocols
•Run control applications on operating platform toachieve control objectives
•Distributed nature of network control handled byunderlying system
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
9
4D-like Architecture
Network Control Applications
Node 1
Node 2
Node 3
Meta Management System
Operating Platform
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
10
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
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
11
Operating Platform
Operating Platform
Network View Virtualization
QoS Routing
Inter-Domain
Routing Policy
Shortest Path Routing
Network
Maintenance
Meta Management Interface
B3
B2
B1
C3
C2
C1
A2
A1
A4
A3
B4
ISP Y
ISP Z
ISP X
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
12
Potential Benefits
•Remove implicit dependencies between controls
•Prevent unintended side-effects of ad hoc controlcomposition
•Network control re-configurations are triggeredsystematically
•Protect network from faulty network controls
•A better environment for innovation and evolution
T. S. Eugene Ngeugeneng at cs.rice.edu Rice University
13
Summary
•Ad hoc network control composition leads tounwanted complexity and fragile systems
•It is time to move towards a more principledframework analogous to an operating system
•Challeges: Develop abstractions and services for anetwork control platform
–Network abstractions and interfaces
–Inter-process communication
–Scheduling
–Synchronization
–Resource management
–Protection