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? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-1 Configuring Campus Switches to Support Voice modating Voice Traffic on Campus Switches ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-2 QoS and Voice Traffic in the Campus Model ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-3 LAN-Based Classification and Marking ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-4 Layer 2 Marking: , CoS ? User Priority field is also called class of service ( CoS ). ? Different types of traffic are assigned different CoS values. ? CoS 6 and 7 are reserved for network use. ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-5 Layer 3 Marking: IP Precedence, DSCP ? IPv4 – Three most significant bits of ToS byte are called IP precedence. – Other bits are unused. ? DiffServ – Six most significant bits of ToS byte are called DiffServ Code Point (DSCP). – DSCP is patible with IP precedence. – Remaining two bits are used for flow control. ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-6 Classification Tools: Trust Boundaries ? A device is “ trusted ” if it correctly classifies packets. ? For scalability, classification should be done as close to the edge as possible. ? The outermost trusted devices represent the “ trust boundary. ” and are optimal; is acceptable (if the access switch cannot perform classification). 123 ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-7 Configuring a Switch for Attachment of a Cisco IP Phone ? Voice traffic tagged for voice VLAN ? Data VLAN traffic from PC can be – Untrusted – Trusted – Set to a specific value ? 2006 Cisco Systems, Inc. All rights reserved. BCMSN — 7-8 Basic mands to Support Attachment of a Cisco IP Phone Configure voice VLAN ? switchport voice vlan 110 Configure trust and CoS options ? mls qos trust cos ? mls qos trust device cisco -phone ? mls qos extend trust ? switchport p