3com 8807 참조 가이드
QoS Commands
247
In the case of network congestion, the switch drops packets to release system
resources. And then no packets are put into long-delay queues. The following two
drop modes are available:
resources. And then no packets are put into long-delay queues. The following two
drop modes are available:
■
Tail drop mode: different queues (red, yellow and green) are allocated with
different drop thresholds. When these thresholds are exceeded respectively,
excessive packets will be dropped.
different drop thresholds. When these thresholds are exceeded respectively,
excessive packets will be dropped.
■
WRED drop mode: Drop precedence is taken into account in drop action.
When only min-thresholds of red, yellow and green packets are exceeded,
packets between min-thresholds and max-thresholds are dropped randomly at
a given slope. But when max-thresholds of red, yellow and green packets are
exceeded, all excessive packets will be dropped.
When only min-thresholds of red, yellow and green packets are exceeded,
packets between min-thresholds and max-thresholds are dropped randomly at
a given slope. But when max-thresholds of red, yellow and green packets are
exceeded, all excessive packets will be dropped.
Example
# Set the port Ethernet3/1/1 in WRED drop mode; import WRED 0 as the
threshold.
threshold.
<SW8800> system-view
System View: return to User View with Ctrl+Z.
[SW8800]interface Ethernet3/1/1
[3Com-Ethernet3/1/1] drop-mode wred 0
dscp
Syntax
dscp dscp-list : dscp-value exp-value cos-value local-precedence-value
drop-precedence
drop-precedence
undo dscp dscp-list
View
Conform level view
Parameter
dscp-list: Original DSCP value, which can be a single value or several values, in the
range of 0 to 63. For example, you can type single DSCP value "46", or DSCP
values "0 8 10 16" (space is required between two values).
range of 0 to 63. For example, you can type single DSCP value "46", or DSCP
values "0 8 10 16" (space is required between two values).
dscp-value: Modified DSCP value, in the range of 0 to 63.
exp-value: Modified EXP value, in the range of 0 to 7. EXP is MPLS priority of MPLS
packets.
packets.
cos-value: Modified 802.1p priority value, in the range of 0 to 7
local-precedence-value: Modified local precedence value, in the range of 0 to 7.
drop-precedence: Modified drop precedence value, in the range of 0 to 2.
Description
Use the dscp command to configure the "DSCP + Conform-level ->
Service-parameter" mapping table of current conform level.
Service-parameter" mapping table of current conform level.
Use the undo dscp command to restore default configuration of the "DSCP +
Conform-level -> Service- parameter" mapping table.
Conform-level -> Service- parameter" mapping table.