Cisco WS-C3560E-48PD-SF Command Reference - Page 304

mls qos trust Chapter 2 Catalyst 3560 Switch Cisco IOS Commands mls qos trust Use the mls qos trust interface configuration command to configure the port trust state. Ingress traffic can be trusted, and classification is performed by examining the packet Differentiated Services Code Point (DSCP), class of service (CoS), or IP-precedence field. Use the no form of this command to return a port to its untrusted state. mls qos trust [cos | device cisco-phone | dscp | ip-precedence] no mls qos trust [cos | device | dscp | ip-precedence] Syntax Description cos device cisco-phone dscp ip-precedence (Optional) Classify an ingress packet by using the packet CoS value. For an untagged packet, use the port default CoS value. (Optional) Classify an ingress packet by trusting the CoS or DSCP value sent from the Cisco IP Phone (trusted boundary), depending on the trust setting. (Optional) Classify an ingress packet by using the packet DSCP value (most significant 6 bits of 8-bit service-type field). For a non-IP packet, the packet CoS is used if the packet is tagged. For an untagged packet, the default port CoS value is used. (Optional) Classify an ingress packet by using the packet IP-precedence value (most significant 3 bits of 8-bit service-type field). For a non-IP packet, the packet CoS is used if the packet is tagged. For an untagged packet, the port default CoS value is used. Defaults The port is not trusted. If no keyword is specified when the command is entered, the default is dscp. Command Modes Interface configuration Command History Release 12.1(19)EA1 12.2(20)SE Modification This command was introduced. The usage guidelines were revised to describe how the switch sets the trust state when a Cisco IP Phone is connected to a switch or routed port. Usage Guidelines Packets entering a quality of service (QoS) domain are classified at the edge of the domain. When the packets are classified at the edge, the switch port within the QoS domain can be configured to one of the trusted states because there is no need to classify the packets at every switch within the domain. Use this command to specify whether the port is trusted and which fields of the packet to use to classify traffic. When a port is configured with trust DSCP or trust IP precedence and the incoming packet is a non-IP packet, the CoS-to-DSCP map is used to derive the corresponding DSCP value from the CoS value. The CoS can be the packet CoS for trunk ports or the port default CoS for nontrunk ports. If the DSCP is trusted, the DSCP field of the IP packet is not modified. However, it is still possible that the CoS value of the packet is modified (according to DSCP-to-CoS map). 2-272 Catalyst 3560 Switch Command Reference 78-16405-05