Help me!! Catalyst 3560/3750 QoS

Hi experts!!

I'm having a tough time understanding the logic behind some of the QOS
configs for the 2970/3560/3750.

1. Why on earth would we want DSCP 0 to be remarked (upwards) to CS1
(Scavenger) as I thought that the whole idea behind remarking to mark
traffic downwards?

<mls qos map policed-dscp 0 24 to 8>

2. Are the ingress policing values below optimal? (got them from SRND) and
why is the burst set to 8000 for all policed values?

I'm would rather do egress policing on the uplink going to the SP switch
rather than having to think about correct individual ingress values for each
port and then calculate the aggregrated bw towards the uplinks, but these
switches don't support egress policing.

Is there a better way?

CAT2970(config) #mls qos map cos-dscp 0 8 16 24 32 46 48 56
      ! Modifies CoS-to-DSCP mapping to map CoS 5 to DSCP EF
CAT2970(config) #mls qos map policed-dscp 0 24 to 8
      ! Excess VVLAN & DVLAN traffic will be remarked to Scavenger (CS1)
CAT2970(config) #
CAT2970(config) #
CAT2970(config) #class-map match-all VVLAN-VOICE
CAT2970(config-cmap) # match access-group name VVLAN-VOICE
CAT2970(config-cmap) #
CAT2970(config-cmap) #class-map match-all VVLAN-CALL-SIGNALING
CAT2970(config-cmap) # match access-group name VVLAN-CALL-SIGNALING
CAT2970(config-cmap) #
CAT2970(config-cmap) #class-map match-all VVLAN-ANY
CAT2970(config-cmap) # match access-group name VVLAN-ANY
CAT2970(config-cmap) #
CAT2970(config-cmap) #
CAT2970(config-cmap) #policy-map IPPHONE+PC-BASIC
CAT2970(config-pmap) #class VVLAN-VOICE
CAT2970(config-pmap-c) # set ip dscp 46 ! DSCP EF (Voice)
CAT2970(config-pmap-c) # police 128000 8000 exceed-action drop
     ! Only one voice call is permitted per switchport VVLAN
CAT2970(config-pmap-c) #class VVLAN-CALL-SIGNALING
CAT2970(config-pmap-c) # set ip dscp 24 ! DSCP CS3 (Call-Signaling)
CAT2970(config-pmap-c) # police 32000 8000 exceed-action
policed-dscp-transmit
     ! Out-of-profile Call-Signaling is marked down to Scavenger (CS1)
CAT2970(config-pmap-c) #class VVLAN-ANY
CAT2970(config-pmap-c) # set ip dscp 0
CAT2970(config-pmap-c) # police 32000 8000 exceed-action
policed-dscp-transmit
      ! Unauthorized VVLAN traffic is marked down to Scavenger (CS1)
CAT2970(config-pmap-c) #class class-default
CAT2970(config-pmap-c) # set ip dscp 0
CAT2970(config-pmap-c) # police 5000000 8000 exceed-action
policed-dscp-transmit
      ! Out-of-profile data

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Received on Mon Aug 23 2010 - 11:34:30 ART