Design Goals:

• Accommodate heterogeneous receivers
• Accommodate different applications with different resource requirements
• Make multicast a first class service, with adaptation to multicast group membership
• Leverage existing multicast/unicast routing with adaptation to changes in underlying unicast, multicast routes
• Control protocol overhead to grow linearly as # receivers
• modular design for heterogeneous underlying technologies

Overview of Operation:

1. Senders and receivers join a multicast group

• Done outside of RSVP
• Senders need not join group

2. Sender-to-Network signalling:

• Path Message: Communicates sender info, and reverse-path-to-sender routing info
• Path teardown: delete senders path state from routers

3. Receiver-to-Network signalling:

• Reservation Message: Reservations flow upstream from receiver to sender, reserving resources, creating additional receiver related state at routers
• Reservation teardown: remove receiver reservations

4. Network-to-End system signalling:

• Path Error
• Reservation Error

RSVP uses soft-state:

• Senders periodically resend path messages to refresh state
• Receivers periodically resent reservations messages to refresh state
• Path and reserve messages have TTL field, specifying refresh intervals