Nortel business policy switch 2000, Руководство пользователя

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290 Chapter 4 Policy-enabled networks
208700-C
QoS classes
The BPS 2000 supports the following Nortel Networks QoS classes:
• Critical and Network classes have the highest priority over all other traffic.
• Premium class is an end-to-end service functioning similarly to a virtual
leased line. Traffic in this service class is normally guaranteed an agreed-upon
peak bandwidth. Traffic requiring this service should be shaped at the network
boundary in order to undergo a negligible delay and delay variance. This
service class is suitable for real-time applications like video and voice over IP.
The recommended PHB for this service is the Expedited Forwarding (EF)
PHB.
• Platinum, Gold, Silver, and Bronze classes use the Assured Forwarding (AF)
PHB. These classes are used for real-time, delay-tolerant traffic and
non-real-time, mission-critical traffic.
• Standard class is the best-effort IP service with an additional, optional use of
traffic classification
that is used at the network boundary to request a better
effort treatment for packets that are in-profile (packets that do not break the
service agreements between the user and the service provider).
Table 56 describes the service classes and the required treatment.
Table 56 Service classes
Traffic category Service class Application type Required treatment
Critical network control Critical Critical network control
traffic Highest priority over all other
traffic. Guaranteed minimum
bandwidth.
Standard network control Network Standard network control
traffic Priority over user traffic.
Guaranteed minimum
bandwidth.
Real time, delay
intolerant, fixed
bandwidth Premium Interhuman
communications requiring
interaction (such as VoIP). Absolute bounded priority over
user traffic. No packet loss for
in-profile traffic. Virtual leased
line with lowest amount of
latency. Provisioned for peak
rate.
Real time, delay tolerant,
low variable bandwidth Platinum Interhuman
communications requiring
interaction with additional
minimal delay (such as
low-cost VoIP). Higher-priority scheduling
providing guaranteed minimum
provisioned bandwidth.
Competes for additional
bandwidth.