Programming with ANTS

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Programming with ANTS

• ANTS facilitates protocols construction and
  deployment
• Demonstrate some examples using
• Mobility services
• Multicasting

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Mobility Services

• Involves 2 types of capsules
• One is sent by mobile hosts to register
  forwarding information while its roaming
• Other is used by other hosts (source) to send
  messages to the mobile host while its roaming
• Home Agent is used to intercept messages at the
  base location of the mobile host
• Foreign Agent is used as a care of address to
  reach the mobile host while its away from its base

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• Mobile Hosts role
• Periodically send Register capsules to their
  Home Agent Via the Foreign Agent
• This capsule updates forwarding address cached
  at the home and the foreign Agent
• Home Agents role
• When other sources send information for the
  Mobile Host, capsule discovers a forwarding
  pointer as it traverses the home agent and
  follows it to the foreign agent
• Foreign Agents role
• Maintains a pointer to the Mobile Host
• When it receives a capsule intended for the
  Mobile Host it simply forwards it

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Multicast

• Consists of 2 types of capsules
• Subscribe capsules Send by applications that
  wish to receive messages sent by a particular
  sender, send these towards the sender
• Multicast Data capsule To multicast to the
  group, the sender node sends these capsules which
  simple route themselves along the distribution
  tree

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• Subscribe program
• Looks up the forwarding record for the group in
  the node cache or creates a new one if none is
  found
• To distinguish between different multicast
  sessions in the cache
• The record is stored in a key which is a
  combination of the group and the senders address
• Once a forwarding record is located, a reverse
  pointer in the direction of the subscriber is
  merged into the forwarding record
• (Leaf subscribers have empty forwarding lists)

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• Multicast Data program
• Makes use of the forwarding records found at the
  nodes, sending copies along every indicated
  reverse path.
• At end systems where there is an empty
  forwarding record, capsule is delivered to the
  application.
• special multicast routers are not needed this
  scheme is localized to the nodes using this
  protocol

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Prototype Implementation

• Done in JAVA
• Classes Involved
• Node class Represents the runtime of a single
  network node
• Channel class Provides interface to the link
  layer connecting nodes via point-to-point or
  shared medium channels
• Capsule class virtual class to create capsules
  specialized to protocols
• Application class Container for end system
  processing that provides a small API for
  registering protocols, injecting capsules into
  the network and receiving capsules from the
  network.

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Source http//www.cs.washington.edu/research/netw
orking/ants/ants-thesis.ps.gz
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Related work done in this field are on websites
below
David Weatherall's thesis http//www.cs.washingt
on.edu/research/networking/ants/ants-thesis.ps.gz
(pg 135)
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Conclusion

• Allows new protocols to be automatically,
  dynamically, and rapidly deployed to exact those
  nodes where needed
• Required no advanced consensus about the kinds
  or definitions of the protocols.
• Can provide means for automatically upgrading
  network protocols can remove barriers to
  innovation, stimulate experimentation, and hasten
  the arrival of new functionality.