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Thursday, February 6, 2014

NTS: QoS

QoS



  • Congestion Management
    • WFQ (Weighted Fair Queuing)
      • fair-queue
    • CQ (Custom Queuing)
      • custom-queue
    • PQ (Priority Queuing)
      • priority-queue
    • CBWFQ (Class-Based WFQ)
      • MQC & bandwidth
    • LLQ (Low Latency Queuing)
      • MQC & priority
  • Congestion Avoidance
    • Tail-Drop
      • default
    • WRED (Weighted Random Early Detection) 
      • random-detect
    • Class-Based WRED
      • MQC & random-detect


Don't forget the set the interface "max-reserved-bandwidth" if more than 75% is required.


Weighted Fair Queuing

  • configure congestion threshold
  • configure dynamic queues
  • configure reservable queues


IOS
interface Serial2/0
 fair-queue 512 256 128


IOS
R2#sh queueing fair
Current fair queue configuration:

  Interface           Discard    Dynamic  Reserved  Link    Priority
                      threshold  queues   queues    queues  queues
  Serial2/0           512        256      128       8       1
R2#sh queueing int s2/0
Interface Serial2/0 queueing strategy: fair
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/512/0 (size/max total/threshold/drops)
     Conversations  0/0/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1158 kilobits/sec



Custom Queuing

  • assign packets/protocols to the 16 queues
  • configure custom queue parameters
  • assign custom queue to interface

Not applicable to subinterfaces.

IOS
queue-list 1 protocol ip 0 list 100
queue-list 1 protocol ipv6 1
queue-list 1 protocol pppoe 2
queue-list 1 default 3
!
queue-list 1 queue 0 byte-count 5000 limit 500
queue-list 1 queue 1 byte-count 2500 limit 250
queue-list 1 queue 2 byte-count 1500 limit 150
queue-list 1 queue 3 byte-count 1500 limit 50
!
interface FastEthernet0/0
 custom-queue-list 1


IOS
R4#sh queueing custom
Current custom queue configuration:

List   Queue  Args
1      3      default
1      2      protocol ip          list 100
1      1      protocol ipv6
1      2      protocol pppoe-sessi
1      0      byte-count 5000 limit 500
1      1      byte-count 2500 limit 250
1      2      limit 150
1      3      limit 50
R4#sh queueing int fa0/0
Interface FastEthernet0/0 queueing strategy: custom

Output queue utilization (queue/count)
        0/680 1/0 2/48085 3/1 4/0 5/0 6/0 7/0 8/0
        9/0 10/0 11/0 12/0 13/0 14/0 15/0 16/0



Priority Queuing

  • assign packets/protocols to the 4 priority queues
  • configure priority queue parameters
  • assign priority queues to interface
Not applicable to subinterfaces.

IOS
priority-list 1 protocol ip high list 100
priority-list 1 protocol ipv6 medium
priority-list 1 protocol pppoe normal
priority-list 1 default low

!
priority-list 1 queue-limit 500 250 150 50
!interface FastEthernet0/0
 priority-group 1


IOS
R4#sh queueing priority
Current DLCI priority queue configuration:
Current priority queue configuration:

List   Queue  Args
1      low    default
1      normal protocol ip          list 100
1      medium protocol ipv6
1      normal protocol pppoe-sessi
1      high   limit 500
1      medium limit 250
1      normal limit 150
1      low    limit 50
R4#sh queueing int fa0/0
Interface FastEthernet0/0 queueing strategy: priority

Output queue utilization (queue/count)
        high/2349 medium/0 normal/48090 low/2


WRED

  • choose between dscp and precedence WRED
  • configure dscp/prec parameters


IOS
interface Serial2/0
 random-detect dscp-based


IOS
R2#sh queueing int s2/0
Interface Serial2/0 queueing strategy: random early detection (WRED)
    Exp-weight-constant: 9 (1/512)
    Mean queue depth: 0

   dscp          Random drop      Tail drop    Minimum Maximum  Mark
                  pkts/bytes       pkts/bytes    thresh  thresh  prob
   af11      0/0              0/0           33      40  1/10
   af12      0/0              0/0           28      40  1/10
   af13      0/0              0/0           24      40  1/10
   af21      0/0              0/0           33      40  1/10
   af22      0/0              0/0           28      40  1/10
   af23      0/0              0/0           24      40  1/10
   af31      0/0              0/0           33      40  1/10
   af32      0/0              0/0           28      40  1/10
   af33      0/0              0/0           24      40  1/10
   af41      0/0              0/0           33      40  1/10
   af42      0/0              0/0           28      40  1/10
   af43      0/0              0/0           24      40  1/10
    cs1      0/0              0/0           22      40  1/10
    cs2      0/0              0/0           24      40  1/10
    cs3      0/0              0/0           26      40  1/10
    cs4      0/0              0/0           28      40  1/10
    cs5      0/0              0/0           31      40  1/10
    cs6      0/0              0/0           33      40  1/10
    cs7      0/0              0/0           35      40  1/10
     ef      0/0              0/0           37      40  1/10
   rsvp      0/0              0/0           37      40  1/10
default       0/0              0/0           20     40  1/10



If WRED is used for a used-defined class, then bandwidth reservation must be made too.

If WRED is used for the default class, then either bandwidth reservation of fair-queue must be used too.


at

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