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Asynchronous Transfer Mode (ATM) Module Installation and User Guide
3-41
Configuring QoS Functions
In addition, a network element that complies with the DiffServ standards must also
provide a recommended default code point, which must be unique for code points in the
standard space. The default PHB describes the common, best-effort forwarding behavior
offered by existing network elements, as defined in RFC 1812.
As an additional differentiation, a set of code points has been allocated for use as the
Class Selector code points, which describe the minimum forwarding handling
requirements needed to preserve compatibility with existing practices while respecting
flexibility for the future.
Table 3-12 and the command examples that follow show how the standard per-hop
behaviors (PHBs) might be mapped onto ExtremeWare QoS profiles qp1 through qp8.
Table 3-10: Assured Forwarding Classes and Three-Level Drop Precedence
Drop-Precedence Level
AF1
AF2
AF3
AF4
Low drop precedence
(AF11) 001010
(AF21) 010010
(AF31) 011010
(AF41) 100010
Medium drop precedence
(AF12) 001100
(AF22) 010100
(AF32) 011100
(AF42) 100100
High drop precedence
(AF13) 001110
(AF23) 010110
(AF33) 011110
(AF43) 100110
Table 3-11: Assured Forwarding Classes and Two-Level Drop Precedence
Drop-Precedence Level
AF1
AF2
AF3
AF4
Low drop precedence
(AF11) 001010
(AF21) 010010
(AF31) 011010
(AF41) 100010
High drop precedence
(AF12) 001100
(AF22) 010100
(AF32) 011100
(AF42) 100100
(AF13) 001110
(AF23) 010110
(AF33) 011110
(AF43) 100110
Table 3-12: Mapping PHBs to QoS Profiles
PHB
Default
Class Selector
AF1
AF2
AF3
AF4
EF
QoS
Profile
qp1
qp2
qp3
qp4
qp5
qp6
qp7
qp8
DSCP
000000
001000
010000
011000
100000
101000
110000
111000
001010
001100
001110
010010
010100
010110
011010
011100
011110
100010
100100
100110
101110
Summary of Contents for BlackDiamond 6800
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