IBM RackSwitch G8000, Application Manual

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RackSwitch G8000: Application Guide
• Assured Forwarding (AF)—This PHB contains four service levels, each with a
different drop precedence, as shown in the following table. Routers use drop
precedence to determine which packets to discard last when the network
becomes congested. AF PHB is described in RFC 2597.
• Class Selector (CS)—This PHB has eight priority classes, with CS7 representing
the highest priority, and CS0 representing the lowest priority, as shown in the
following table. CS PHB is described in RFC 2474.
QoS Levels
Table 14 shows the default service levels provided by the switch, listed from highest
to lowest importance:
Drop
Precedence
Class 1 Class 2 Class 3 Class 4
Low AF11 (DSCP 10) AF21 (DSCP 18) AF31 (DSCP 26) AF41 (DSCP 34)
Medium AF12 (DSCP 12) AF22 (DSCP 20) AF32 (DSCP 28) AF42 (DSCP 36)
High AF13 (DSCP 14) AF23 (DSCP 22) AF33 (DSCP 30) AF43 (DSCP 38)
Priority Class Selector DSCP
Highest CS7 56
CS6 48
CS5 40
CS4 32
CS3 24
CS2 16
CS1 8
Lowest CS0 0
Table 14. Default QoS Service Levels
Service Level Default PHB 802.1p Priority
Critical CS7 7
Network Control CS6 6
Premium EF, CS5 5
Platinum AF41, AF42, AF43, CS4 4
Gold AF31, AF32, AF33, CS3 3
Silver AF21, AF22, AF23, CS2 2
Bronze AF11, AF12, AF13, CS1 1
Standard DF, CS0 0