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COS class-default bandwidth allocation

Seeking clarification as to if the class-default would utilize available remaining bandwidth based on the remaining bandwidth and queue packet limit config. 

 

I have a 12416 | Cisco IOS XR Software, Version 4.1.2

2XT1 multilink interface as follows:

 

!
interface Multilink0/10/0/0/115
 service-policy input V4_Ex_20:60:30:10_in
 service-policy output V4_Ex_20:60:30:10_out_4M
 vrf 13979:283866
 ipv4 address 192.168.10.126 255.255.255.252
 encapsulation ppp
 keepalive disable
!

The question concerns service-policy output V4_Ex_20:60:30:10_out_4M....

!
policy-map V4_Ex_20:60:30:10_out_4M
 class cos1_class
  priority level 1
  police rate percent 20 burst 250 ms peak-burst 250 ms
   exceed-action drop
  !
 !
 class control_class
  bandwidth percent 5
  queue-limit 320 packets
 !
 class cos2_class
  bandwidth remaining percent 60
  random-detect dscp 24,26 192 packets 320 packets
  random-detect dscp 25,27,28,29,30,31 96 packets 160 packets
  queue-limit 320 packets
 !
 class cos3_class
  bandwidth remaining percent 30
  random-detect dscp 16,18 192 packets 320 packets
  random-detect dscp 17,19,20,21,22,23 96 packets 160 packets
  queue-limit 320 packets
 !
 class class-default
  bandwidth remaining percent 10
  queue-limit 320 packets
 !
 end-policy-map
!

 

Based on this configuration would the class-default not utilize any existing remaining bandwidth as needed versus tail dropping as it is per the output below..? The end user is knowingly not tagging the COS 2 traffic correctly therefore causing much of the traffic to flow to the class-default bucket...although we will get this corrected I was wondering why the packets got dropped regardless of the tagging as I understood the class-default would consume remaining bandwidth. Is the bandwidth remaining and queue limit config lines as configured above putting restrictions on this capability? Any feedback would be greatly appreciated. I have scrubbed lots of documentation but finding it hard to place my finger on something decisive. 

Multilink0/10/0/0/115 output: V4_Ex_20:60:30:10_out_4M

Class cos1_class
  Classification statistics          (packets/bytes)     (rate - kbps)
    Matched             :            14331896/1068064350           31
    Transmitted         :            14331814/1067962471           31
    Total Dropped       :                  82/101879               0
  Policing statistics                (packets/bytes)     (rate - kbps)
    Policed(conform)    :            14331814/1067962471           31
    Policed(exceed)     :                  82/101879               0
    Policed(violate)    :                   0/0                    0
    Policed and dropped :                  82/101879
  Queueing statistics
    Queue ID                             : 304
    High watermark                       : N/A
    Inst-queue-len  (packets)            : 0
    Avg-queue-len   (packets)            : 0
    Taildropped(packets/bytes)           : 0/0
Class control_class
  Classification statistics          (packets/bytes)     (rate - kbps)
    Matched             :                   0/0                    0
    Transmitted         :                   0/0                    0
    Total Dropped       :                   0/0                    0
  Queueing statistics
    Queue ID                             : 302
    High watermark                       : N/A
    Inst-queue-len  (packets)            : 0
    Avg-queue-len   (packets)            : 0
    Taildropped(packets/bytes)           : 0/0
Class cos2_class
  Classification statistics          (packets/bytes)     (rate - kbps)
    Matched             :                   0/0                    0
    Transmitted         :                   0/0                    0
    Total Dropped       :                   0/0                    0
  Queueing statistics
    Queue ID                             : 300
    High watermark                       : N/A
    Inst-queue-len  (packets)            : 0
    Avg-queue-len   (packets)            : 0
    Taildropped(packets/bytes)           : 0/0
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0

    WRED profile for Label 1
    DSCP:  24 26
    RED Transmitted (packets/bytes)      : N/A
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0
    WRED profile for Label 2
    DSCP:  25 27 28 29 30 31
    RED Transmitted (packets/bytes)      : N/A
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0
Class cos3_class
  Classification statistics          (packets/bytes)     (rate - kbps)
    Matched             :             1324919/478941081            2
    Transmitted         :             1324919/478941081            2
    Total Dropped       :                   0/0                    0
  Queueing statistics
    Queue ID                             : 301
    High watermark                       : N/A
    Inst-queue-len  (packets)            : 0
    Avg-queue-len   (packets)            : 0
    Taildropped(packets/bytes)           : 0/0
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0

    WRED profile for Label 1
    DSCP:  16 18
    RED Transmitted (packets/bytes)      : N/A
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0
    WRED profile for Label 2
    DSCP:  17 19 20 21 22 23
    RED Transmitted (packets/bytes)      : N/A
    RED random drops(packets/bytes)      : 0/0
    RED maxthreshold drops(packets/bytes): 0/0
Class class-default
  Classification statistics          (packets/bytes)     (rate - kbps)
    Matched             :            54233413/24240606239          546
    Transmitted         :            54099865/24154788424          546
    Total Dropped       :              133548/85817815             0
  Queueing statistics
    Queue ID                             : 303
    High watermark                       : N/A
    Inst-queue-len  (packets)            : 9
    Avg-queue-len   (packets)            : 1
    Taildropped(packets/bytes)           : 133548/85817815

 

 

 

1 REPLY
Cisco Employee

Looks like you have a SIP700

Looks like you have a SIP700 card, this one is CPP based (as opposed to Typhoon NPU based on the ether LC's).

you need to check the command show qos-hal for that linecard to see what the programming looks like for that queue.

in this config snippet you show, with bandwidth and bw remaining you set the CIR of the queue.

so now you're applying a minimum bw to that queue and hence a weighted ratio.

if you omit that, it will get whatever is left, but it is scheduled in an MDRR methodology.

xander

Xander Thuijs CCIE #6775 Principal Engineer ASR9000, CRS, NCS6000 & IOS-XR
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