End-to-end quality of service (QoS) and service priority signalling in H.323 systems Amendment 1: New Annex A "IntServ/RSVP support for H.323 systems", Annex B "DiffServ support for H.323 systems" and Annex C "Priority support for H.323 systems" (Study Gr
H.361 Amendment 1 introduces three new annexes.
Annex A describes the procedures of H.323 QoS signalling when RSVP-based QoS signalling is
used in the transport plane. Resource Reservation Protocol (RSVP) is the QoS signalling protocol
used in the Integrated Services (IntServ) architecture. RSVP is a path-based QoS mechanism which
is used to reserve resources for both individual flows and flow aggregates. RSVP can be used in a
pure IntServ architecture or can be coupled with Differentiated Services architecture (DiffServ) to
provide IntServ operation over DiffServ network. This Annex describes the procedures for H.323
QoS to allow the use of RSVP in the transport plane.
Annex B describes the procedures of H.323 QoS signalling under the Differentiated Services
(DiffServ) architecture in the transport plane. DiffServ is a class-based QoS architecture which
supports in-band signalling. The signalling occurs via a value defined in the differentiated services
(DS) field of the IP header. This value is referred to as the Differentiated Services Code Point
(DSCP). The packet forwarding treatment given to a packet in a network device is based on the
DSCP value.
Annex C describes the QoS service priority support signalling used for H.323 systems. The service
priority mechanism defines procedures and constructs within the signalling plane that are used to
prioritize bearer traffic during periods of resource contention. This allows traffic of higher priority
to receive preferred QoS treatment.