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
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.
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