User guide

3-56 Packet Over SONET Module Installation and User Guide
Configuring the PoS Module
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 3-11 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 3-9: 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 3-10: 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 3-11: 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