1. Programmable Packets in the Emerging Extreme Internet David Culler UC Berkeley Intel Research @ Berkeley

2. 8/7/2002Programmable Packets The emerging internet of 2012 won’t be dominated by independent, point-to- point transport between ‘desktops’ 99.9% of the network nodes will be the billions of devices deeply embedded in the physical world –they are the majority today, but not connected to each other or the web.... This will change. –they will generate a phenomenal amount of data Broad-coverage services spread over a substantial portions of the web serve millions at once –CDNs and P2Ps the tip of the iceberg These ‘extreme’ network environments may present a much greater need for programmability –may also be more condusive to generality –very different attack models and response

3. 8/7/2002Programmable Packets Outline Motivation Deeply embedded networks of tiny devices Planetary-scale Services Discussion

4. 8/7/2002Programmable Packets Deeply Embedded Networks # nodes >> # people sensor/actuator data stream unattended inaccessible prolonged deployment energy constrained operate in aggregate in-network processing necessary what they do changes over time => must be programmed over the network

5. 8/7/2002Programmable Packets Berkeley Wireless Sensor ‘Motes’ Mote TypeWeCReneRene2DotMica DateSep-99Oct-00Jun-01Aug-01Feb-02 Microcontroller (4MHz) TypeAT90LS8535ATMega163ATMega103/128 Prog. Mem. (KB)816128 RAM (KB)0.514 Communication RadioRFM TR1000 Rate (Kbps)1010/40 Modulation TypeOOKOOK/ASK

6. 8/7/2002Programmable Packets TinyOS Application Graph RFM Radio byte Radio Packet UART Serial Packet ADC Tempphoto Active Messages clocks bit byte packet Route map routersensor appln application HW SW Example: self-organized ad- hoc, multi-hop routing of photo sensor readings 3450 B code 226 B data Graph of cooperating state machines on shared stack

7. 8/7/2002Programmable Packets It is a noisy world after all... Get to rethink each of the layers in a new context –coding, framing –mac –routing –transport, –rate control –discovery –multicast –aggregation –naming –security –... Resource constrained, power aware, highly variable,... Every node is also a router No entrenched ‘dusty packets’ probability of reception from center node vs xmit strength

8. 8/7/2002Programmable Packets Example “epidemic” tree formation

9. 8/7/2002Programmable Packets Tiny Virtual Machines? TinyOS components graph supports a class of applns. Application flexibility / extendability needed –Re-tasking deployed networks –Adjusting parameters Binary program uploading takes ~2 minutes –significant energy cost, vulnerable transition Tiny virtual machine adds layer of interpretation for specific coordination –Primitives for sensing and communication –Small capsules (24 bytes) –Propagate themselves through network

10. 8/7/2002Programmable Packets Maté Overview TinyOS component 7286 bytes code, 603 bytes RAM Stack-based bytecode interpreter Three concurrent execution contexts Code broken into capsules of 24 instructions Single instruction message send Self-forwarding code for rapid programming Message receive and send contexts

11. 8/7/2002Programmable Packets Maté Network VM Architecture 0123 Subroutines Clock Send Receive Events gets/sets Code Operand Stack Return Stack PC Mate Context 3 execution contexts dual stack, 1-byte inst. Send/Rcv/Clock + sub capsules Hold up to 24 instructions Fit in a single TinyOS AM packet –installation is atomic –no buffering Context-specific inst: send, receive, clock Shared: subroutines 0-3 Version information

12. 8/7/2002Programmable Packets Code Snippet: cnt_to_leds gets # Push heap variable on stack pushc 1 # Push 1 on stack add # Pop twice, add, push result copy # Copy top of stack sets # Pop, set heap pushc 7 # Push 0x0007 onto stack and # Take bottom 3 bits of value putled # Pop, set LEDs to bit pattern halt #

13. 8/7/2002Programmable Packets Sending a Message pushc 1 # Light is sensor 1 sense # Push light reading on stack pushm # Push message buffer on stack clear # Clear message buffer add # Append reading to buffer send # Send message using built-in halt # ad-hoc routing system

14. 8/7/2002Programmable Packets Viral Code Every capsule has version information Maté installs newer capsules it hears on network Motes can forward their capsules (local broadcast) –forw –forwo

15. 8/7/2002Programmable Packets Forwarding: cnt_to_leds gets # Push heap variable on stack pushc 1 # Push 1 on stack add # Pop twice, add, push result copy # Copy top of stack sets # Pop, set heap pushc 7 # Push 0x0007 onto stack and # Take bottom 3 bits of value putled # Pop, set LEDs to bit pattern forw # Forward capsule halt #

16. 8/7/2002Programmable Packets Code Progation 42 motes: 3x14 grid 3 hop network –largest cell 30 motes –smallest cell 15 motes

17. 8/7/2002Programmable Packets Why Tiny Programmable Packets? All programming must be remote –rare opportunities to get to GDI, can’t mess with the birds, minimize disturbance –too many devices to program by hand Network programming of entire code image –essential, but often overkill –takes about 2 minutes of active radio time –window of vulnerability Packet programs propagate very cheaply –if a change will run for less than 6 days, less energy to interpret it ~10,000 instructions per second Task operations are 1/3 of Maté overhead 33:1 to 1.03:1 overhead on TinyOS operations

18. 8/7/2002Programmable Packets Thoughts on the “Many Tiny” Deeply embedded networks of small devices are coming –utilize spatial diversity as well as coding and retransmission –severely constrained resources –self-organization is essential –deal with noise and uncertainty - routinely “Programming the network?” is not a question. –it is necessary –epidemic algorithms common –distributed algorithms (time synch, leader elec,...) –reactive by design –‘learning’ framework is natural (ex. MPR routing) Nodes interact directly with physical world –what they do will matter –potential to observe the effects of actions Models of security & privacy TBD! –very different attack models Deja vu opportunity www.tinyos.org

19. 8/7/2002Programmable Packets The Other Extreme - Planetary Scale Services www.planet-lab.org

20. 8/7/2002Programmable Packets Motivation A new class of services & applications is emerging that spread over a sizable fraction of the web –CDNs as the first examples –Peer-to-peer,... Architectural components are beginning to emerge –Distributed hash tables to provide scalable translation –Distributed storage, caching, instrumentation, mapping, events... The next internet will be created as an overlay on the current one –as did the last one –it will be defined by its services, not its transport »translation, storage, caching, event notification, management There will soon be vehicle to try out the next n great ideas in this area

21. 8/7/2002Programmable Packets Confluence of Technologies Cluster-based scalable distribution, remote execution, management, monitoring tools –UCB Millennium, OSCAR,..., Utah Emulab, ModelNet... CDNS and P2Ps –Gnutella, Kazaa,...,Pastry, Chord, CAN, Tapestry Proxies routine Virtual machines & Sandboxing –VMWare, Janos, Denali,... web-host slices (EnSim) Overlay networks becoming ubiquitous –XBONE, RON, Detour... Akamai, Digital Island,.... Service Composition Frameworks –yahoo, ninja,.net, websphere, Eliza Established internet ‘crossroads’ – colos Web Services / Utility Computing Grid authentication infrastructure Packet processing, –Anets,.... layer 7 switches, NATs, firewalls Internet instrumentation The Time is NOW

22. 8/7/2002Programmable Packets Guidelines (1) Thousand viewpoints on “the cloud” is what matters –not the thousand servers –not the routers, per se –not the pipes, per se

23. 8/7/2002Programmable Packets Guidelines (2) and you miust have the vantage points of the crossroads –primarily co-location centers

24. 8/7/2002Programmable Packets Guidelines (3) Each service needs an overlay covering many points –logically isolated Many concurrent services and applications –must be able to slice nodes = > VM per service –service has a slice across large subset Must be able to run each service / app over long period to build meaningful workload –traffic capture/generator must be part of facility Consensus on “a node” more important than “which node”

25. 8/7/2002Programmable Packets Guidelines (4) Test-lab as a whole must be up a lot –global remote administration and management »mission control –redundancy within Each service will require its own remote management capability Testlab nodes cannot “bring down” their site –generally not on main forwarding path –proxy path –must be able to extend overlay out to user nodes? Relationship to firewalls and proxies is key Management, Management, Management

26. 8/7/2002Programmable Packets Guidelines (5) Storage has to be a part of it –edge nodes have significant capacity Needs a basic well-managed capability –but growing to the seti@home model should be considered at some stageseti@home –may be essential for some services

27. 8/7/2002Programmable Packets Initial Researchers (mar 02) Washington Tom Anderson Steven Gribble David Wetherall MIT Frans Kaashoek Hari Balakrishnan Robert Morris David Anderson Berkeley Ion Stoica Joe Helerstein Eric Brewer John Kubi Intel Research David Culler Timothy Roscoe Sylvia Ratnasamy Gaetano Borriello Satya Milan Milenkovic Duke Amin Vadat Jeff Chase Princeton Larry Peterson Randy Wang Vivek Pai Rice Peter Druschel Utah Jay Lepreau CMU Srini Seshan Hui Zhang UCSD Stefan Savage Columbia Andrew Campbell ICIR Scott Shenker Mark Handley Eddie Kohler see http://www.cs.berkeley.edu/~culler/planetlab

28. 8/7/2002Programmable Packets Initial Planet-Lab Candidate Sites Intel Berkeley ICIR MIT Princeton Cornell Duke UT Columbia UCSB UCB UCSD UCLA UW Intel Seattle KY Melbourne Cambridge Harvard GIT Uppsala Copenhagen CMU UPenn WI Chicago Utah Intel OR UBC Washu ISI Intel Rice Beijing Tokyo Barcelona Amsterdam Karlsruhe St. Louis

29. 8/7/2002Programmable Packets Approach:Service-Centric Virtualization Virtual Machine Technology has re-emerged for hosting complete desktop environments on non-native OS’s and potentially on machine monitors. –ex. VMWare,... Sandboxing has emerged to emulate multiple virtual machines per server with limited /bin, (no /dev) –ex. ENSim web hosting Network Services require fundamentally simpler virtual machines, can be made far more scalable (VMs per PM), focused on service requirements –ex. Jail, Denali, scalable and fast, but no full legacy OS –access to overlays (controlled access to raw sockets) –allocation & isolation »proportional scheduling across resource container - CPU, net, disk –foundation of security model –fast packet/flow processing puts specific design pressures Instrumentation and management are additional virtualized ‘slices’ –distributed workload generation, data collection

30. 8/7/2002Programmable Packets Hard problems/challenges “Slice-ability” – multiple experimental services deployed over many nodes –Distributed Virtualization –Isolation & Resource Containment –Proportional Scheduling –Scalability Security & Integrity - remotely accessed and fully exposed –Authentication / Key Infrastructure proven, if only systems were bug free –Build secure scalable platform for distributed services »Narrow API vs. Tiny Machine Monitor Management –Resource Discovery, Provisioning, Overlay->IP –Create management services (not people) and environment for innovation in management »Deal with many as if one Building Blocks and Primitives –Ubiquitous overlays Instrumentation

31. 8/7/2002Programmable Packets Programmable Packets w/i a Slice A service spread over the globe needs to be extensible through methods more lightweight than ‘reload all the code’ –not unlike the ‘new router firmware’ problem Smart Packets interpreted in the context of the containing service-slice, rather than generic core-router. Routing is overlay routing, so not limited by CISCO design cycle ‘Global view’ gives the service many advantages –not just localization / caching –adaptive or multipath routing in the overlay –multi-lateration in the network space »consider a global spam filter Reactive loops within a service are natural –service-driven load balancing, overlay management, SEDA-style processing

32. 8/7/2002Programmable Packets Discussion Wide-Area Broad-Coverage Services Traditional pt-pt Internet Deeply- Embedded Networks

33. 8/7/2002Programmable Packets Security: restricted API -> Simple Machine Monitor Authentication & Crypto works… if underlying SW has no holes  very simple system  push complexity up into place where it can be managed  virtualized services Classic ‘security sandbox’ limits the API and inspects each request Ultimately can only make very tiny machine monitor truly secure SILK effort (Princeton) captures most valuable part of ANets nodeOS in Linux kernel modules –controlled access to raw sockets, forwarding, proportional alloc Key question is how limited can be the API –ultimately should self-virtualize »deploy the next planetlab within the current one –progressively constrain it, introducing compatibility box –minimal box defines capability of thinix Host  1 planetSILK within  2 thinix VM