WAN interface drop packet, but not reaching max. bandwidth

[R T]

I have a 10M WAN link between two offices, but I found that there is a tail drop and WRED drop. Just wonder why it was dropped under the max. bandwidth... I'm not sure whether there is a mis-configuration... 
<LOG>
-------------------------------------------------------------------------------------------------- 
show policy-map int gi1/1/1 
 GigabitEthernet1/1/1

  Service-policy output: Shape_9M

    Class-map: class-default (match-any)
      45896657 packets, 33444526808 bytes
      5 minute offered rate 1997000 bps, drop rate 0 bps
      Match: any
      Traffic Shaping
        Average Rate Traffic Shaping
        CIR 9000000 (bps)
      Output Queue:
        Queue Actively Shaped: No

      Service-policy : Segment1-Segment2

        Class-map: Segment1-Vlans (match-any)
          45494315 packets, 33406372492 bytes
          5 minute offered rate 1996000 bps, drop rate 0 bps
          Match: vlan  46
          Match: vlan  47
          Bandwidth 4000 (kbps)
          Traffic Shaping
            Average Rate Traffic Shaping
            CIR 8000000 (bps)
          Output Queue:
            Queue Actively Shaped: No

          Service-policy : WAN-1

            Class-map: class-default (match-any)
              45494315 packets, 33406372492 bytes
              5 minute offered rate 1996000 bps, drop rate 0 bps
              Match: any
              random-detect exponential-weighting-constant 9
              prec     min-threshold    max-threshold    mark-probablity
              ----------------------------------------------------------
              0          56                 95               1/ 2
              1          72                 100              1/ 3
              2          80                 105              1/ 4
              3          88                 110              1/ 6
              4          96                 120              1/ 7
              5          104                128              1/10
              6          112                128              1/10
              7          120                128              1/10

              Output Queue:
                Current Queue Depth: 0
                Tail Drop Threshold: 128
                Tail Packets Drop: 180582
                Tail Bytes Drop: 137921882
                Current Average Queue Length: 7
                WRED Packets Drop: 19181
                WRED Bytes Drop: 29079067

        Class-map: Segment2-Vlans (match-any)
          271542 packets, 21200402 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: vlan  42
          Match: vlan  43
          Bandwidth 4000 (kbps)
          Traffic Shaping
            Average Rate Traffic Shaping
            CIR 8000000 (bps)
          Output Queue:
            Queue Actively Shaped: No

          Service-policy : WAN-1

            Class-map: class-default (match-any)
              271542 packets, 21200402 bytes
              5 minute offered rate 0 bps, drop rate 0 bps
              Match: any
              random-detect exponential-weighting-constant 9
              prec     min-threshold    max-threshold    mark-probablity
              ----------------------------------------------------------
              0          56                 95               1/ 2
              1          72                 100              1/ 3
              2          80                 105              1/ 4
              3          88                 110              1/ 6
              4          96                 120              1/ 7
              5          104                128              1/10
              6          112                128              1/10
              7          120                128              1/10

              Output Queue:
                Current Queue Depth: 0
                Tail Drop Threshold: 128
                Tail Packets Drop: 0
                Tail Bytes Drop: 0
                Current Average Queue Length: 0
                WRED Packets Drop: 0
                WRED Bytes Drop: 0

        Class-map: class-default (match-any)
          130800 packets, 16953914 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: any

-----------------------------------------------------------------------
<Configuration>
----------------------------------------------------------------------- 
class-map match-any Segment1-Vlans
 match vlan 46
 match vlan 47
class-map match-any Segment2-Vlans
 match vlan 42
 match vlan 43
!
policy-map WAN-1
 class class-default
     random-detect
     random-detect precedence 0 56 95 2
     random-detect precedence 1 72 100 3
     random-detect precedence 2 80 105 4
     random-detect precedence 3 88 110 6
     random-detect precedence 4 96 120 7
     random-detect precedence 5 104 128 10
     random-detect precedence 6 112 128 10
     random-detect precedence 7 120 128 10
policy-map Segment1-Segment2
 class Segment1-Vlans
    bandwidth 4000
    shape average 8000000
  service-policy WAN-1
 class Segment2-Vlans
    bandwidth 4000
    shape average 8000000
  service-policy WAN-1
policy-map Shape_9M
 class class-default
    shape average 9000000
service-policy Segment1-Segment2 !

interface GigabitEthernet1/1/1
 switchport trunk allowed vlan 42,43,46,47
 switchport mode trunk
 logging event trunk-status
 logging event spanning-tree
 logging event status
 mls qos trust ip-precedence
 service-policy output Shape_9M

[R T]

<Hostname>#show policy-map int gi1/1/1
 GigabitEthernet1/1/1

  Service-policy output: Shape_9M

    Class-map: class-default (match-any)
      45992095 packets, 33501156147 bytes
      5 minute offered rate 2136000 bps, drop rate 9000 bps
      Match: any
      Traffic Shaping
        Average Rate Traffic Shaping
        CIR 9000000 (bps)
      Output Queue:
        Queue Actively Shaped: No

      Service-policy : Segment1-Segment2

        Class-map: Segment1-Vlans (match-any)
          45589416 packets, 33462969983 bytes
          5 minute offered rate 2135000 bps, drop rate 9000 bps
          Match: vlan  46
          Match: vlan  47
          Bandwidth 4000 (kbps)
          Traffic Shaping
            Average Rate Traffic Shaping
            CIR 8000000 (bps)
          Output Queue:
            Queue Actively Shaped: No

          Service-policy : WAN-1

            Class-map: class-default (match-any)
              45589416 packets, 33462969983 bytes
              5 minute offered rate 2135000 bps, drop rate 9000 bps
              Match: any
              random-detect exponential-weighting-constant 9
              prec     min-threshold    max-threshold    mark-probablity
              ----------------------------------------------------------
              0          56                 95               1/ 2
              1          72                 100              1/ 3
              2          80                 105              1/ 4
              3          88                 110              1/ 6
              4          96                 120              1/ 7
              5          104                128              1/10
              6          112                128              1/10
              7          120                128              1/10

              Output Queue:
                Current Queue Depth: 0
                Tail Drop Threshold: 128
                Tail Packets Drop: 181240
                Tail Bytes Drop: 138553980
                Current Average Queue Length: 3
                WRED Packets Drop: 19182
                WRED Bytes Drop: 29079135

        Class-map: Segment2-Vlans (match-any)
          271769 packets, 21218128 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: vlan  42
          Match: vlan  43
          Bandwidth 4000 (kbps)
          Traffic Shaping
            Average Rate Traffic Shaping
            CIR 8000000 (bps)
          Output Queue:
            Queue Actively Shaped: No

          Service-policy : WAN-1

            Class-map: class-default (match-any)
              271769 packets, 21218128 bytes
              5 minute offered rate 0 bps, drop rate 0 bps
              Match: any
              random-detect exponential-weighting-constant 9
              prec     min-threshold    max-threshold    mark-probablity
              ----------------------------------------------------------
              0          56                 95               1/ 2
              1          72                 100              1/ 3
              2          80                 105              1/ 4
              3          88                 110              1/ 6
              4          96                 120              1/ 7
              5          104                128              1/10
              6          112                128              1/10
              7          120                128              1/10

              Output Queue:
                Current Queue Depth: 0
                Tail Drop Threshold: 128
                Tail Packets Drop: 0
                Tail Bytes Drop: 0
                Current Average Queue Length: 0
                WRED Packets Drop: 0
                WRED Bytes Drop: 0

        Class-map: class-default (match-any)
          130910 packets, 16968036 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: any

[Joseph W. Doherty]

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Posting

"Just wonder why it was dropped under the max. bandwidth..."

You know this how?

Are you familiar with the concept of micro bursts?  If not, search for it on the Internet, and read up on it.

If you're still puzzled, please post a follow-on question to this thread.