QoS assurance
Have to specify service-level (e.g. guaranteed?)
- lose flexibility over cost? (service-level decides cost)
- better/more appropriate service levels in the future
- differentiated services
- receiver heterogeneity in multicast group
RSVP:
- if failure: carry on at best-effort (or new RSVP set-up)
- may not be practicable in some cases
- may not be end-to-end in some cases