Introduction

• Active networks allow users to inject customized programs into nodes.
• can permit new computations to happen in-network
• advantages of active networks by exchanging active programs rather than passive packets
  • exchanging code has a basis for adaptive protocols
  • capsules provide a means of implementing fine-grained application-specific functions
  • programming abstract is a powerful platform for user-driven customization

Lead users

• firewalls
  • implement filters to determine which packet should be passed transparently and which should be blocked
  • tend to implement application and user-specific functions in addition to routing
  • active network could considerably automate process of adding new functions or rules into firewalls
• web proxies
  • cache and serve www traffic
  • algorithms to automatically balance cache hierarchy by re-positioning caches themselves
  • web pages with js code make the case for programs to dynamically generate page content in network on the cache side
• mobile gateways
  • observes and adapts connection to network depending on physical conditions
  • w/ active network, can choose to compress traffic (or not)
• other domains
  • multi-point communication strategies
  • information fusion > fuse within the network

Active Networks

• discrete approach to programmable switches
  • processing is separate from program loading
  • header message identifies the program to be run
  • operators allowed to load code into routers
• capsules - integrated approach
  • every message sent is a program
  • program + data
  • capsule execution can result in 0 or more outgoing capsules
• programming with capsules
  • simple application: compute next hop + schedule outgoing packets
  • active routing - capsule can dynamically enumerate and evaluate paths while being routed
• ways to reach beyond capsule environment
  • foundation components – universally available services outside of capsule
    • capsules may require access to service such as routing tables, link states, etc. Need a standard library of services
  • active storage – modify node storage after capsule execution complete
    • leave information behind for new capsules to read
    • “flows” rather than connections
  • extensibility – allow programs to define new classes/methods
    • inefficient for programs to be always alongside data
    • need a way to push some of the code into the network device with small reference to run program in-packet
• interoperable programming model
  • capsules require mobility
  • must be transmittable across network, portable
  • must also be safe+efficient

Capsule Programs

• capsule primitives
  • list of primitive actions a capsule may perform
  • all nodes on a path must be capable of executing the program
• safety and efficiency
  • restrict execution primitives available to programs
  • programming language to foster efficiency
  • can go with interpreted (e.g. python), intermediate (java bytecode) or binary (platform dependent)
  • run-time compilation of C programs
• java-like instruction-set

Node Resources

• need basic resource specification, platform independent
  • transmission bandwidth
  • processing capacity
  • transient storage
• link abstraction to encompass unit of bandwidth allocation and traffic patterns
• instruction execution – assign capsules default allocations (# of instr?)
• transient storage for aggregation of capsules - plus garbage collection
• active storage – soft+persistent
  • soft: cache objects like hints/flow state. do not survive restarts
  • persistent..self-explanatory
• resource safety
  • safe manipulation of node resources: partitioned into few activities
  • validation of user requests for resources
  • automated delegation of resource authorizations

Internet to ActiveNet

• researchers should attempt to deploy wide-area ActiveNet

  • overlay on traditional infrastructure