HP ProCurve Series 6120 Blade Switches Advanced Traffic Management Guide

5-27
Quality of Service (QoS): Managing Bandwidth More Effectively
Using QoS Classifiers To Configure Quality of Service for Outbound Traffic
codepoint and corresponding 802.1p priority. (Use the qos dscp-map
command to specify a priority for any codepoint, see “Differentiated
Services Codepoint (DSCP) Mapping” on page 5-51.)
• Assign an 802.1p Priority: This option reads the DSCP of an
incoming IPv4 packet and, without changing this codepoint, assigns
the 802.1p priority to the packet, as configured in the DSCP Policy
Table (page 5-51). This means that a priority value of 0 - 7 must be
configured for a DSCP before the switch will attempt to perform a
QoS match on the packet’s DSCP bits.
Before configuring the ToS Diffserv mode, you must use the qos dscp-map
command to configure the desired 802.1p priorities for the codepoints you
want to use for either option. See “Differentiated Services Codepoint
(DSCP) Mapping” on page 5-51 for more information.
Unless IP-Precedence mode and Diffserv mode are both disabled (the default
setting), enabling one automatically disables the other. For more on ToS
operation, refer to “Details of QoS IP Type-of-Service” on page 5-36.
Assigning an 802.1p Priority to IPv4 Packets on the Basis
of the ToS Precedence Bits
If a device or application upstream of the switch sets the precedence bits in
the ToS byte of IPv4 packets, you can use this feature to apply that setting for
prioritizing packets for outbound port queues. If the outbound packets are in
a tagged VLAN, this priority is carried as an 802.1p value to the adjacent
downstream devices.
Syntax: qos type-of-service ip-precedence
Causes the switch to automatically assign an 802.1p prior-
ity to all IPv4 packets by computing each packet’s 802.1p
priority from the precedence bits the packet carries. This
priority determines the packet’s queue in the outbound port
to which it is sent. If the packet leaves the switch on a tagged
port, it carries the 802.1p priority with it to the next
downstream device. (ToS IP Precedence Default: Disabled)
no qos type-of-service
Disables all ToS classifier operation, including prioritiza-
tion using the precedence bits.