QoS HQF (3 Level) Configuration

zakir.ahmed · ‎07-21-2013

I would like to share a 2 level QoS config first and then the same config using 3 level -

!

! Example 1

!

class-map match-any C-EF

match dscp cs5 ef

!

class-map match-any C-AF4

match dscp cs4 af41 af42 af43

!

class-map match-any C-AF3

match dscp cs3 af31 af32 af33

!

class-map match-any C-AF2

match dscp cs2 af21 af22 af23

!

class-map match-any C-AF1

match dscp cs1 af11 af12 af13

!

policy-map CHILD-POLICY-1

class C-EF

priority percent 20

class C-AF4

bandwidth remaining percent 25

class C-AF3

bandwidth remaining percent 25

class C-AF2

bandwidth remaining percent 24

class C-AF1

bandwidth remaining percent 24

!

policy-map 2-LEVEL

class class-default

shape average 10000000

service-policy CHILD-POLICY-1

!

interface FastEthernet0

service-policy output 2-LEVEL

!

#show policy-map interface fastEthernet0

FastEthernet0

Service-policy output: 2-LEVEL

Class-map: class-default (match-any)

9 packets, 1271 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: any

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 9/1313

shape (average) cir 10000000, bc 40000, be 40000

target shape rate 10000000

Service-policy : CHILD-POLICY-1

queue stats for all priority classes:

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

Class-map: C-EF (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs5 (40) ef (46)

0 packets, 0 bytes

30 second rate 0 bps

Priority: 20% (2000 kbps), burst bytes 50000, b/w exceed drops: 0

Class-map: C-AF4 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs4 (32) af41 (34) af42 (36) af43 (38)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 25% (2000 kbps)

Class-map: C-AF3 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs3 (24) af31 (26) af32 (28) af33 (30)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 25% (2000 kbps)

Class-map: C-AF2 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs2 (16) af21 (18) af22 (20) af23 (22)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 24% (1920 kbps)

Class-map: C-AF1 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs1 (8) af11 (10) af12 (12) af13 (14)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 24% (1920 kbps)

Class-map: class-default (match-any)

9 packets, 1271 bytes

30 second 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) 9/1313

!

! Example 2

!

class-map match-any C-EF

match dscp cs5 ef

!

class-map match-any C-AF4

match dscp cs4 af41 af42 af43

!

class-map match-any C-AF3

match dscp cs3 af31 af32 af33

!

class-map match-any C-AF2

match dscp cs2 af21 af22 af23

!

class-map match-any C-AF1

match dscp cs1 af11 af12 af13

!

class-map match-any C-AF4-AF3

match dscp cs4 af41 af42 af43 cs3 af31 af32 af33

!

class-map match-any C-AF2-AF1

match dscp cs2 af21 af22 af23 cs1 af11 af12 af13

!

policy-map AF4-AF3-CHILD

class C-AF4

bandwidth remaining percent 50

class C-AF3

bandwidth remaining percent 49

!

policy-map AF2-AF1-CHILD

class C-AF2

bandwidth remaining percent 50

class C-AF1

bandwidth remaining percent 49

!

policy-map CHILD-POLICY-2

class C-EF

priority percent 20

class C-AF4-AF3

bandwidth remaining percent 50

service-policy AF4-AF3-CHILD

class C-AF2-AF1

bandwidth remaining percent 48

service-policy AF2-AF1-CHILD

!

policy-map 3-LEVEL

class class-default

shape average 10000000

service-policy CHILD-POLICY-2

!

interface FastEthernet0

service-policy output 3-LEVEL

!

#show policy-map interface fastEthernet0

FastEthernet0

Service-policy output: 3-LEVEL

Class-map: class-default (match-any)

162 packets, 17737 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: any

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 162/18081

shape (average) cir 10000000, bc 40000, be 40000

target shape rate 10000000

Service-policy : CHILD-POLICY-2

queue stats for all priority classes:

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

Class-map: C-EF (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs5 (40) ef (46)

0 packets, 0 bytes

30 second rate 0 bps

Priority: 20% (2000 kbps), burst bytes 50000, b/w exceed drops: 0

Class-map: C-AF4-AF3 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs3 (24) af31 (26) af32 (28) af33 (30) cs4 (32) af41 (34) af42 (36) af43 (38)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 50% (4000 kbps)

Service-policy : AF4-AF3-CHILD

Class-map: C-AF4 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs4 (32) af41 (34) af42 (36) af43 (38)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 50% (2000 kbps)

Class-map: C-AF3 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs3 (24) af31 (26) af32 (28) af33 (30)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 49% (1960 kbps)

Class-map: class-default (match-any)

0 packets, 0 bytes

30 second 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) 0/0

Class-map: C-AF2-AF1 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs1 (8) af11 (10) af12 (12) af13 (14) cs2 (16) af21 (18) af22 (20) af23 (22)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 48% (3840 kbps)

Service-policy : AF2-AF1-CHILD

Class-map: C-AF2 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs2 (16) af21 (18) af22 (20) af23 (22)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 50% (1920 kbps)

Class-map: C-AF1 (match-any)

0 packets, 0 bytes

30 second offered rate 0 bps, drop rate 0 bps

Match: dscp cs1 (8) af11 (10) af12 (12) af13 (14)

0 packets, 0 bytes

30 second rate 0 bps

Queueing

queue limit 64 packets

(queue depth/total drops/no-buffer drops) 0/0/0

(pkts output/bytes output) 0/0

bandwidth remaining 49% (1881 kbps)

Class-map: class-default (match-any)

0 packets, 0 bytes

30 second 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) 0/0

Class-map: class-default (match-any)

162 packets, 17737 bytes

30 second 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) 162/18081

In both examples (2-Level and 3-Level), the five classes (EF/AF4/AF3/AF2/AF1) are allocated almost the same amount of bandwidth. During the congestion period, if there is no traffic in the AF4 Class the unused bandwidth (2000 kbps) will be shared between AF3, AF2, and AF1 classes (first example - 2-Level).

But in the 2nd example (3-Level), if there is no traffic in the AF4 class during the congestion period, the unused bandwidth (2000 kbps) will be used by the AF3 class first because AF3 and AF4 are under the same parent class C-AF4-AF3 (4000 Kbps). The unused bandwidth from AF4 class will not be shared with AF2 and AF1 as long as AF3 class needs 50% (4000 Kbps) of the link bandwidth.

Please confirm if my understanding is correct.

Joseph W. Doherty · ‎07-22-2013

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Posting

In both examples (2-Level and 3-Level), the five classes (EF/AF4/AF3/AF2/AF1) are allocated almost the same amount of bandwidth. During the congestion period, if there is no traffic in the AF4 Class the unused bandwidth (2000 kbps) will be shared between AF3, AF2, and AF1 classes (first example - 2-Level). 
But in the 2nd example (3-Level), if there is no traffic in the AF4 class during the congestion period, the unused bandwidth (2000 kbps) will be used by the AF3 class first because AF3 and AF4 are under the same parent class C-AF4-AF3 (4000 Kbps). The unused bandwidth from AF4 class will not be shared with AF2 and AF1 as long as AF3 class needs 50% (4000 Kbps) of the link bandwidth.
Please confirm if my understanding is correct.

I believe your understanding is incorrect.

What CBWFQ really does is assign a weight to the flows. It uses that weight relative to other flows for bandwidth scheduling.

In both your 2 layer and 3 layer polices, your four classes would get about the same weight, so they will all be processed alike regardless of whether the defining policy was 2 layer or 3 layer.