HP ProCurve Series 2810 Management And Configuration Manual page 159

Precedence Criteria Overview
1 UDP/TCP Takes precedence based on a layer 4 UDP or TCP application, with a user-specified application
port number (for example, Telnet). Default state: Disabled
If a packet does not meet the criteria for UDP/TCP priority, then precedence defaults to the Device Priority
type, below.
2 Device Takes precedence based on an inbound packet having a particular destination or source IP
Priority address. QoS applies the following IP address limits:
(IP
• Up to 60 IP addresses
Address)
If a given packet has a destination IP address matching a QoS configuration, this packet takes
precedence over another packet that has the matching IP address as a source address. (This
can occur, for example, on an outbound port in a switch mesh environment.) Also, if the source
and destination IP addresses (SA and DA) in the same packet match for different QoS policies,
the DA takes precedence. Default state: No IP address prioritization.
If a packet does not meet the criteria for device priority, then precedence defaults to the IP Type of Service
(ToS) type, below.
3 IP Type- Takes precedence based on the TOS field in IP packets. (Applies only to IP packets.) The ToS
of- field is configured by an upstream device or application before the packet enters the switch.
Service
• IP Precedence Mode: QoS reads an inbound packet's IP precedence (upper three) bits in
(IP ToS)
• Differentiated Services (Diffserve) Mode: QoS reads an inbound IP packet's differentiated
For more on IP ToS, see "QoS IP Type-of-Service (ToS) Policy and Priority" on page 6-33. Default
state: Disabled.
If a packet does not meet the criteria for ToS priority, then precedence defaults to the VLAN type
4 VLAN Takes precedence based on the ID number of the VLAN in which the inbound packet exists.
Priority For example, if the default VLAN (VID = 1) and the "Blue" VLAN (with a VID of 20) are both
assigned to a port, and Blue VLAN traffic is more important, you can configure QoS to give Blue
VLAN traffic a higher priority than default VLAN traffic. (Priority is applied on the outbound
port.) Default state: No-override.
If a packet does not meet the criteria for VLAN priority, then precedence defaults to the Interface (Source-
Port) type, below.
precedence supersedes VLAN precedence, all TCP port 80 packets on VLAN
100 will be set to normal priority. For a type precedence listing, see table 6-4,
''Switch Type Search Order and Precedence'', on page 6-10.
Table 6-5. Precedence Criteria for QoS types
the Type-of-Service (ToS) byte and automatically assigns an 802.1p priority to the packet (if
specified in the QoS configuration) for outbound transmission.
services, or codepoint (upper six), bits of the Type-of-Service (TOS) byte. Packet
prioritization depends on the configured priority for the codepoint. (Some codepoints default
to the DSCP standard, but can be overridden.)
Quality of Service (QoS): Managing Bandwidth More Effectively
Introduction
6-11