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Rising star

Catalyst 9300 QoS Output Drops

Hello folks,


I've got an issue with a new Catalyst 9300 deployment for a customer.  We've moved routing from a dedicated router to the 9300 and the 9300 has taken the QoS for the site.  We're using standard Auto QoS, trusting DSCP, but I'm seeing significant output drops on the WAN bound interface.  Can anyone help shed some light on to what is going on?  The stats don't seem to add up correctly on the port-map.  The WAN providers interface is nailed to 100/Full and the Auto QoS is set to run in percentages of the interface and has dutifully set it's figures to a 100 Mbps reference bandwidth.  I've upgraded the switches from 16.09.01 to 16.12.01, but that didn't clear the problem.  I can't quite understand from the show policy-map what the drops in the priority-queue 1 are from, as it doesn't seem to be matching anything and there's no traffic on the site marked that should hit the priority-queue.


Here is a show interface:-

GigabitEthernet1/0/1 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is c4b3.6a05.7c81 (bia c4b3.6a05.7c81)
  Description: Network::WAN
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 2/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Carrier delay is 0 msec
  Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
  input flow-control is on, output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:01, output 00:00:08, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/200000/0/0 (size/max/drops/flushes); Total output drops: 35615
  Queueing strategy: Class-based queueing
  Output queue: 0/200000 (size/max)
  30 second input rate 34000 bits/sec, 34 packets/sec
  30 second output rate 966000 bits/sec, 102 packets/sec
     120258 packets input, 66898060 bytes, 0 no buffer
     Received 2703 broadcasts (2702 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 2702 multicast, 0 pause input
     0 input packets with dribble condition detected
     285906 packets output, 310294634 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out


Show policy-map int g1/0/1:-


  Service-policy input: AutoQos-4.0-Trust-Dscp-Input-Policy

    Class-map: class-default (match-any)
      291057 packets
      Match: any
      QoS Set
         dscp dscp table AutoQos-4.0-Trust-Dscp-Table

  Service-policy output: AutoQos-4.0-Output-Policy

    queue stats for all priority classes:
      priority level 1

      (total drops) 50316915
      (bytes output) 52157956

    Class-map: AutoQos-4.0-Output-Priority-Queue (match-any)
      0 packets
      Match:  dscp cs4 (32) cs5 (40) ef (46)
      Match: cos  5
      Priority: 30% (30000 kbps), burst bytes 750000,

      Priority Level: 1

    Class-map: AutoQos-4.0-Output-Control-Mgmt-Queue (match-any)
      0 packets
      Match:  dscp cs2 (16) cs3 (24) cs6 (48) cs7 (56)
      Match: cos  3

      queue-limit dscp 16 percent 80
      queue-limit dscp 24 percent 90
      queue-limit dscp 48 percent 100
      queue-limit dscp 56 percent 100
      (total drops) 0
      (bytes output) 915388
      bandwidth remaining 10%

      queue-buffers ratio 10

    Class-map: AutoQos-4.0-Output-Multimedia-Conf-Queue (match-any)
      0 packets
      Match:  dscp af41 (34) af42 (36) af43 (38)
      Match: cos  4

      (total drops) 0
      (bytes output) 303
      bandwidth remaining 10%
      queue-buffers ratio 10

    Class-map: AutoQos-4.0-Output-Trans-Data-Queue (match-any)
      0 packets
      Match:  dscp af21 (18) af22 (20) af23 (22)
      Match: cos  2

      (total drops) 0
      (bytes output) 0
      bandwidth remaining 10%
      queue-buffers ratio 10

    Class-map: AutoQos-4.0-Output-Bulk-Data-Queue (match-any)
      0 packets
      Match:  dscp af11 (10) af12 (12) af13 (14)
      Match: cos  1

      (total drops) 0
      (bytes output) 0
      bandwidth remaining 4%
      queue-buffers ratio 10

    Class-map: AutoQos-4.0-Output-Scavenger-Queue (match-any)
      0 packets
      Match:  dscp cs1 (8)

      (total drops) 0
      (bytes output) 0
      bandwidth remaining 1%
      queue-buffers ratio 10

    Class-map: AutoQos-4.0-Output-Multimedia-Strm-Queue (match-any)
      0 packets
      Match:  dscp af31 (26) af32 (28) af33 (30)

      (total drops) 0
      (bytes output) 0
      bandwidth remaining 10%
      queue-buffers ratio 10

    Class-map: class-default (match-any)
      0 packets
      Match: any

      (total drops) 0
      (bytes output) 259417210
      bandwidth remaining 25%
      queue-buffers ratio 25

Show run int g1/0/1:-

interface GigabitEthernet1/0/1
 description Network::WAN
 switchport access vlan 900
 switchport trunk native vlan 999
 switchport mode access
 switchport nonegotiate
 bandwidth 100000
 bandwidth qos-reference 100000
 ip flow monitor FNF-monitor-SolarWinds-in input
 ip flow monitor FNF-monitor-SolarWinds-out output
 ip arp inspection trust
 load-interval 30
 carrier-delay msec 0
 speed 100
 duplex full
 snmp ifindex persist
 storm-control broadcast level 50.00
 storm-control multicast level 50.00
 storm-control action trap
 auto qos trust dscp
 spanning-tree portfast trunk
 service-policy input AutoQos-4.0-Trust-Dscp-Input-Policy
 service-policy output AutoQos-4.0-Output-Policy
 hold-queue 200000 in
 hold-queue 200000 out
 ip dhcp snooping trust


Any insight or thoughts, greatly appreciated.


Best, Leigh