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What is pass-through mode?

April 26, 2017mode pass-through

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What is pass-through mode?

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A. In pass-through mode, the switch uses the class of service (CoS) value of incoming packets without a modification of the differentiated services code point (DSCP) value. The frame can pass through the switch with both the incoming CoS and DSCP values intact. When you disable pass-through mode and configure the switch port to trust CoS, the DSCP value is derived from the CoS-to-DSCP map. In this case, the DSCP usually changes as a result. In Cisco IOS Software releases earlier than Cisco IOS Software Release 12.1(11)EA1, this derivation of the DSCP value is on by default and you cannot change it. In Cisco IOS Software Release 12.1(11)EA1 and later, you can configure this with the enablement of pass-through mode on the port. Here is a sample configuration: interface fastethernet 0/1 switchport mode access mls qos trust cos pass-through dscp Q. Can I reclassify the class of service (CoS) value of data that are generated from a PC that connects to an IP phone? The IP phone attaches to a