2.3 Reservation Set-Up Protocol (RSVP)



 
  This protocol should be actually designed for a multicast environment.In general, an RSVP reservation request specifies the amount of resources to be reserved for all. The resource quantity is specified by a 'flowspec' and the packet subset to receive those resources is specified by a 'filter spec'.

There can be two types for reservation setup protocols:

i) Hard State-which is connection oriented, and under this approach the connection is made and removed completely under the networks responsibility.

ii) Soft State- which is connectionless, and this saves the reservation state in it's cache which is updated periodically by the end hosts.RSVP uses the Soft State method for reservation protocols.

Another important point to be noted here is that the RSVP protocol should scale well with large multicast groups.It should also give the flexibility of adding one sender or receiver to an existing set-up or at the same time deleting a sender or a receiver.

2.3.1Overview:-

RSVP supports multicast transmission. Multicast distribution replicates each data from a sender for delivery to every receiver. RSVP request specifies the amount of resources to be reserved for all/subset of packets. As explained before, the 'flowspec' in the scheduler, attributes the parameters required for the class and the 'filterspec' maps the appropriate packets in the classifier.
RSVP should be implemented on links which will adhere to the reservation of resources.The link path should contain a huge capacity which is unreserved and can be used for a new flow.But in case of link failure, there should be a possibility of adapting a alternate path, the one which also satisfies the above two conditions.