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

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

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 Agent’s 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 Agent’s role: Maintains a pointer to the Mobile Host When it receives a capsule intended for the Mobile Host it simply forwards it

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

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 sender’s 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)

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

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.

Source: http://www. cs. washington

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

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.