zl50415 Zarlink Semiconductor, zl50415 Datasheet - Page 40

• Manufacturer Part Number: zl50415
• Description: Managed 16-port 10/100 M + 2-port 1 G Ethernet Switch
• Manufacturer: Zarlink Semiconductor

7.11
The mapping between priority classes discussed in this chapter and elsewhere is shown below.
As the table illustrates, P7 is used solely for network management (NM) frames. P6 is used for expedited
forwarding service (EF). Classes P2 through P5 correspond to an assured forwarding (AF) group of size 4. Finally,
P0 and P1 are two best effort (BE) classes.
For 10/100 Mbps ports, the classes of Table 9 are merged in pairs—one class corresponding to NM+EF, two AF
classes and a single BE class.
Features of the ZL50418 that correspond to the requirements of their associated IETF classes are summarized in
the table below.
Table 10 - Mapping between ZL50418 and IETF Diffserv Classes for Gigabit Ports
Mapping to IETF Diffserv Classes
Network management (NM) and
Expedited forwarding (EF)
Assured forwarding (AF)
Best effort (BE)
Table 11 - Mapping between ZL50418 and IETF Diffserv Classes for 10/100 Ports
ZL
IETF
ZL
IETF
Table 12 - ZL50418 Features Enabling IETF Diffserv Standards
P7
NM
P3
NM+EF
P6
EF
P5
AF0
Global buffer reservation for NM and EF
Shaper for EF traffic on 1 Gbps ports
Option of strict priority scheduling
No dropping if admission controlled
Four AF classes for 1 Gbps ports
Programmable bandwidth partition, with option of WFQ
service
Option of delay-bounded service keeps delay under fixed
levels even if not admission-controlled
Random early discard, with programmable levels
Global buffer reservation for each AF class
Two BE classes for 1 Gbps ports
Service only when other queues are idle means that QoS not
adversely affected
Random early discard, with programmable levels
Traffic from flow control enabled ports automatically classified
as BE
Zarlink Semiconductor Inc.
ZL50418
P4
AF1
P2
AF0
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P3
AF2
P1
AF1
P2
AF3
P1
BE0
P0
BE0
P0
BE1
Data Sheet