Hi,
I was wondering in anyone has came across the same problem:
Implementing parent policy map with shaping on class-default on Cisco
871 or 1841 will cause higher jitter on child traffic class even if it
is LLQ. I guess it should be the same behavior on other Cisco access
platforms.
Example:

policy-map Child
class voip
priority 500
police 500000
class data
bandwidth 400

policy-map Parent
class class-default
shape average 2000000
service-policy Child

Interface FastEthernet 4
service-policy output Parent

After trying different burst size parameters on parent shaping I found
out that jitter can be minimized by reducing parent shaping burst
size. By minimizing this parameter child policy-map reduced default
allocated bandwidth to class-default - 15% or even less. Which is not
what Cisco tells - 75% + 25%.
I know that Cisco does not recommends to tune shaping burst size, but
I could not find any other way to reduce jitter. IOS Version:
12.4(9)T1


Regards,
Robertas