| Description | This object denotes the PHB which is mapped to the traffic
class given by cggsnQosUmtsTrafficClass.
DS architecture is based on number of functional elements,
one of which is PHB. PHBs specify queuing, queue management
and scheduling characteristics that allow a means of
allocating buffer and bandwidth resources at each node among
the competing traffic streams.
The various DS PHBs include:
signalling - signallingClass(1)
The signalling class PHB is only used for the UMTS
signalling messages. This DS PHB does not apply to
any other IP data packets.
expedited forwarding - efClass(2)
The expedited forwarding PHB is used for providing
a low loss, low latency, low jitter, assured
bandwidth, end-to-end service through the DS domains.
Such a service appears to the endpoints like a
point-to-point connection, or a virtual leased line.
assured forwarding - afClass(3-6)
The assured forwarding PHB provides a means for a
provider DS domain to offer different levels of
delivery assurances for packets received from a
customer DS domain. Four assured forwarding classes:
afClass1, afClass2, afClass3 and afClass4 are defined,
where each AF class is in each DS node allocated a
certain amouont of forwarding resoources(buffer space
and bandwidth). IP packets are assigned into one or
more of these classes, according to the subscribed
service. Within each class the packets are marked
by a mobile subscriber, or by the provider DS domain,
with one of the three possible drop precedence
values. In case of congestion, the drop precedence
of a packet determines the relative importance of a
packet within the class. Packets in one class are
forwarded independently of the packets in another
class.
best effort - bestEffort(7)
This is the default PHB. The packets of this
aggregate are forwarded on an output link whenever
the link is not required to satisfy any other PHB. |