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voice vlan/cos posted 08/03/2003
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If you use this on any given 3550 switchport:

1) mls qos cos 5
   mls qos cos override

   [ Presumably overrides whatever is
     coming into the switch port (voice and data)
     from the phone/pc and sets COS to 5 ]

and then enter this:

2) switchport priority extend cos 5

    [ Presumably instructs the IP phone(?) to
      override whatever cos might be coming from
      an attached PC and sets COS to 5 ]


Is command 2 superfluous?
Could voice traffic theoretically suffer, relative to data, on the way to
the 3550 switch port if an attached PC had all data traffic set at COS 7 and
command 2 was not used.  I guess it comes down to what level of COS
processing/prioritization, if any, can be done by the IP phone with its
integrated switch before info is forwarded on to the 3550 switch.  Thanks in
advance for any comments.  I have seen
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12113ea1/3550scg/s
wvoip.htm
and
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12113ea1/3550scg/s
wqos.htm

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