[c-nsp] 2901 output drops

Alex Pressé alex.presse at gmail.com
Tue Nov 5 14:42:55 EST 2013


This is how traffic shaping works; by dropping packets. I would also add
fair-queueing to each of your classes, as this would allow you to tune
queues:

policy-map WAN-OUT
 class Network-Control
  bandwidth percent 10
  fair-queue
  queue-limit 128 packets
 class class-default
  random-detect dscp-based
  fair-queue 256
  queue-limit 128 packets

You can tune the number of dynamic queues for your environment; look at
your netflow data to get a sense of how many flows are happening during
your busy times. Queueing packets adds delay; which may reduce performance
where simply dropping packets would have sped things up. It's a balancing
act.




On Tue, Nov 5, 2013 at 12:13 PM, Michael Sprouffske
<msprouffske at yahoo.com>wrote:

> I am seeing over a million outputs drops per day.  This
> is a 100Mb mpls connection that is shaping down to 10.  Is there any way to
> improve on my drops ?  Do I need to up my queue
> limit on this interface and if so, what would be a good number to use.
> I’m not sure how to tweak this without breaking things.  I’m really only
> seeing this issue in the best effort queue.
>
>
> Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M),
> Version 15.0(1)M4, RELEASE SOFTWARE (fc1)
>
> interface GigabitEthernet0/1
> description QWEST ELA
> ip address x.x.x.x
> ip flow ingress
> ip flow egress
> duplex full
> speed 100
> service-policy output ELA_SHAPING_POLICY
>
> GigabitEthernet0/1 is up, line protocol is up
>   Hardware is CN Gigabit Ethernet, address is
> 6400.f164.baa9 (bia 6400.f164.baa9)
>   Description: QWEST ELA
>   Internet address is 63.231.1.138/30
>   MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
>      reliability 255/255, txload 17/255,
> rxload 1/255
>   Encapsulation ARPA, loopback not set
>   Keepalive set (10 sec)
>   Full-duplex, 100Mb/s, media type is RJ45
>   output flow-control is unsupported, input
> flow-control is unsupported
>   ARP type: ARPA, ARP Timeout 04:00:00
>   Last input 00:00:03, output 00:00:00, output hang
> never
>   Last clearing of "show interface" counters
> 12w1d
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total
> output drops: 22927282
>   Queueing strategy: Class-based queueing
>   Output queue: 0/1000/0 (size/max total/drops)
>   5 minute input rate 287000 bits/sec, 233 packets/sec
>   5 minute output rate 6807000 bits/sec, 1215
> packets/sec
>      1140353458 packets input, 203684093
> bytes, 0 no buffer
>      Received 0 broadcasts, 0 runts, 0
> giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0
> overrun, 0 ignored
>      0 watchdog, 0 multicast, 0 pause
> input
>
> GigabitEthernet0/1
>
>   Service-policy output: ELA_SHAPING_POLICY
>
>     Class-map: class-default (match-any)
>       3224094436 packets,
> 1840099533264 bytes
>       5 minute offered rate 6800000
> bps, drop rate 21000 bps
>       Match: any
>       Queueing
>       queue limit 64 packets
>       (queue depth/total
> drops/no-buffer drops) 0/22927245/0
>       (pkts output/bytes output)
> 3214611748/1831697074895
>       shape (average) cir 10000000,
> bc 40000, be 40000
>       target shape rate 10000000
>
>       Service-policy :
> ELA_QUEUING_POLICY
>
>         Class-map:
> Priority-One (match-any)
>
> 652548002 packets, 121711798378 bytes
>           5
> minute offered rate 364000 bps, drop rate 0 bps
>
> Match: ip precedence 5
>
> 652547995 packets, 121711796301 bytes
>
> 5 minute rate 364000 bps
>
> Queueing
>           queue
> limit 64 packets
>
> (queue depth/total drops/no-buffer drops) 0/0/0
>           (pkts
> output/bytes output) 652547998/121711798085
>
> bandwidth 40% (4000 kbps)
>
> Exp-weight-constant: 9 (1/512)
>
> Mean queue depth: 0 packets
>
> class     Transmitted
> Random drop      Tail
> drop          Minimum
> Maximum     Mark
>
> pkts/bytes
> pkts/bytes       pkts/bytes
> thresh
> thresh     prob
>
>
> 0
> 0/0
> 0/0
> 0/0
> 20            40
> 1/10
>
> 1
> 0/0
>   0/0
> 0/0
> 22            40
> 1/10
>
> 2
> 0/0
> 0/0
> 0/0
> 24            40
> 1/10
>
> 3
> 0/0
> 0/0
> 0/0
> 26            40
> 1/10
>
> 4
> 0/0
> 0/0
> 0/0
> 28            40
> 1/10
>
> 5
> 2859563189/528793287896
> 0/0
> 0/0
> 30            40
> 1/10
>
> 6
>      0/0
> 0/0
> 0/0
> 32            40
> 1/10
>
> 7
> 0/0
> 0/0
> 0/0
> 34            40
> 1/10
>
>         Class-map:
> Priority-Two (match-any)
>
> 3787671 packets, 767947737 bytes
>           5
> minute offered rate 0 bps, drop rate 0 bps
>
> Match: ip precedence 4  6  7
>
> 3787671 packets, 767947737 bytes
>
> 5 minute rate 0 bps
>
> Queueing
>           queue
> limit 64 packets
>
> (queue depth/total drops/no-buffer drops) 0/0/0
>           (pkts
> output/bytes output) 3787671/330536833
>
> bandwidth 20% (2000 kbps)
>
> Exp-weight-constant: 9 (1/512)
>
> Mean queue depth: 0 packets
>
> class     Transmitted
>     Random drop      Tail
> drop          Minimum
> Maximum     Mark
>
> pkts/bytes
> pkts/bytes
> pkts/bytes
> thresh
> thresh     prob
>
>
> 0
> 0/0
> 0/0
> 0/0
>      20
> 40  1/10
>
> 1
> 0/0
> 0/0
> 0/0
> 22            40
> 1/10
>
> 2
> 0/0
> 0/0
> 0/0
> 24            40
> 1/10
>
> 3
> 0/0
> 0/0
> 0/0
> 26            40
> 1/10
>
> 4
> 6329811/355302154
> 0/0
> 0/0
> 28            40
> 1/10
>
> 5
> 0/0
>   0/0
> 0/0
> 30            40
> 1/10
>
> 6
> 13685632/1194240446
> 0/0
> 0/0
> 32            40
> 1/10
>
> 7
> 1052/1507535
> 0/0
> 0/0
> 34            40
> 1/10
>
>         Class-map:
> Best-effort (match-any)
>           2566808274
> packets, 1717522303645 bytes
>           5
> minute offered rate 6420000 bps, drop rate 21000 bps
>
> Match: ip precedence 0  1
>
> 2566808266 packets, 1717522295369 bytes
>
> 5 minute rate 6420000 bps
>
> Queueing
>           queue
> limit 64 packets
>
> (queue depth/total drops/no-buffer drops) 0/22927245/0
>           (pkts
> output/bytes output) 2543881025/1689309763627
>
> bandwidth 20% (2000 kbps)
>
> Exp-weight-constant: 9 (1/512)
>
> Mean queue depth: 10 packets
>
> class     Transmitted
> Random drop      Tail
> drop          Minimum
> Maximum     Mark
>
> pkts/bytes
> pkts/bytes
> pkts/bytes
> thresh
> thresh     prob
>
>
> 0       11188633262/6901309576156
> 50899436/66626844913
> 23141442/29723879892
> 20            40
> 1/10
>
> 1
> 42293/20533986
> 11/9717           1/121
> 22            40
> 1/10
>
> 2
> 0/0
> 0/0
> 0/0
> 24            40
> 1/10
>
> 3
> 0/0
> 0/0
> 0/0
> 26            40
> 1/10
>
> 4
>  0/0
> 0/0
> 0/0
> 28            40
> 1/10
>
> 5
> 0/0
> 0/0
> 0/0
> 30            40
> 1/10
>
> 6
> 0/0
> 0/0
> 0/0
> 32            40
> 1/10
>
> 7
> 0/0
> 0/0
> 0/0
> 34            40
> 1/10
>
>         Class-map:
> Priority-Three (match-any)
>           81557
> packets, 5666687 bytes
>           5
> minute offered rate 0 bps
>
> Match: ip precedence 2  3
>
> 81557 packets, 5666687 bytes
>
> 5 minute rate 0 bps
>
>         Class-map:
> class-default (match-any)
>
> 868971 packets, 91855955 bytes
>           5
> minute offered rate 0 bps, drop rate 0 bps
>
> Match: any
>
>           queue
> limit 64 packets
>
> (queue depth/total drops/no-buffer drops) 0/0/0
>           (pkts
> output/bytes output) 14395054/20344976350
>
>
> HERE IS THE POLICY MAP
>
>
>
> class-map match-any Best-effort
>  match ip precedence 0  1
> class-map match-any Priority-Three
>  match ip precedence 2  3
> class-map match-any Priority-Two
>  match ip precedence 4  6  7
> class-map match-any Priority-One
>  match ip precedence 5
> !
> !
> policy-map ELA_QUEUING_POLICY
>  class Priority-One
>     bandwidth percent 40
>      random-detect
>  class Priority-Two
>     bandwidth percent 20
>      random-detect
>  class Best-effort
>     bandwidth percent 20
>      random-detect
>  class Priority-Three
> policy-map ELA_SHAPING_POLICY
>  class class-default
>     shape average 10000000
>   service-policy ELA_QUEUING_POLICY
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-- 
Alex Presse
"How much net work could a network work if a network could net work?"


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