HP 6120XG HP ProCurve Series 6120 Blade Switches Advanced Traffic Management G - Page 203
Assigning an 802.1p Priority to IPv4 Packets on the Basis of the ToS Precedence Bits, qos dscp-map
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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 priority 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 prioritization using the precedence bits. 5-27