Allied Telesis AlliedWare Plus 5.2.1, Руководство по программному обеспечению, Страница: 844 / 1294

Quality of Service (QoS)
©2008 Allied Telesis Inc. All rights reserved.
39.12 AlliedWare Plus
TM
Operating System Software Reference C613-50003-00 REV E Software Version 5.2.1
packet’s destination output port. Note that this procedure takes priority over that
described in method (1) above.
These methods and their related commands will be now be described in greater detail.
CoS tagging commands
A number of commands can be used set or change the CoS tag mapping. Table 39-3 shows
the commands that can set or change the CoS tag within a packet.
Table 39-3: CoS Mapping Commands in Hierarchical Order
Note: Where a packet contains both a CoS and a DSCP field, and each field maps to a
different class-map; the switch will apply a priority based on the creation date of the
class maps to which they apply - the earlier the creation date, the higher the priority.
Mapping CoS tags to traffic types
The command mls qos map cos-queue to , enables you to create a switch-wide mapping of
CoS values to egress queues. The default mappings for this command are:
COS : 0 1 2 3 4 5 6 7
--------------------------------
QUEUE: 2 0 1 3 4 5 6 7
These mappings match the CoS guidelines documented in Annex H.2 of ANSI/IEEE 802.1D
1988 Edition. Table H-15 on page 355 of the standard, shows a table of user priorities for
specific traffic types.
Table 39-4 shows an adapted version of the ANSI/IEEE table.
Table 39-4: Traffic Type Guidelines
Command Function
set cos Assigns a CoS tag to a particular class-map / policy map.
mls qos map mark-dscp to Where a packet contains CoS tag and a DSCP tags. The
table set by this command contains a configurable DSCP to
CoS tag mapping.
mls qos map policed-dscp to Finally, the remarking function applied by this command can
remap all previously set CoS tagging.
User Priority
(egress queue)
CoS Value Acronym Traffic type
0 (lowest) 1 BK Background
1 2 - Spare
2 0 BE Best Effort
3 3 EE Excellent Effort
4 4 CL Controlled Load
5 5 VI “Video,” <100 ms latency and jitter
6 6 VO “Voice,” <10 ms latency and jitter
7 (highest) 7 NC Network Control