what is the diff between the two QoS config below?

[hamdinaji]

Dear All,

I have a question, can someone explian for me what is the diff between below two QoS config. i need to what is the diff between applying policy-map inside policy-map then apply it under the interface, or one policy-map and apply it under the interface. Also can i know what is the impact if i will not use class default under the policy map?

Your answer will be highly appreciated.

1)

class-map match-all GOLD
match access-group name CRITICAL_APP
class-map match-all SILVER
match access-group name OTHER_APP

policy-map TRAFFIC_CLASSES
class GOLD
bandwidth <Bandwidth Required e.g. 256>
class SILVER
bandwidth <Bandwidth Required e.g. 128>

policy-map ALL_TRAFFIC
class class-default
shape average 4000000
service-policy TRAFFIC_CLASSES

ip access-list extended CRITICAL_APP
permit ip <source network> <wild card mask> <destination network> <wild card mask>

ip access-list extended OTHER_APP
permit ip <source network> <wild card mask> <destination network> <wild card mask>

interface FastEthernet0/0
bandwidth 4000000
service-policy output ALL_TRAFFIC

2)

class-map match-all GOLD
match access-group name CRITICAL_APP
class-map match-all SILVER
match access-group name OTHER_APP

policy-map TRAFFIC_CLASSES
class GOLD
bandwidth <Bandwidth Required e.g. 256>
class SILVER
bandwidth <Bandwidth Required e.g. 128>

class class-default
shape average 4000000

ip access-list extended CRITICAL_APP
permit ip <source network> <wild card mask> <destination network> <wild card mask>

ip access-list extended OTHER_APP
permit ip <source network> <wild card mask> <destination network> <wild card mask>

interface FastEthernet0/0
bandwidth 4000000
service-policy output TRAFFIC_CLASSES

[Joseph W. Doherty]

The difference between the two examples is major!

If the first example, all your traffic will be shaped to 4 Mbps. If the shaper causes congestion, the traffic will be placed into one of 3 classes (there's always a class-default) for further treatment. If you set Gold and Silver to 256 and 128, Gold is guaranteed to obtain twice the bandwidth of Silver, if they both want it. Since you didn't define class-default, I'm unsure how it will be treated relative to Gold and Silver.

In the second example, if the FE interface physically congests (interface bandwidth statement does not limit it), again traffic will be placed into one of the 3 classes. Also again, Gold and Silver, if they both want bandwidth, will split it 2:1 (again if you assign the values of 256 and 128), but also again, unknown how the 3 classes will "share" as you didn't define bandwidth for class-default. Further, class-default traffic will be shaped to 4 Mbps, regardless whether physical interface is congested or not.