3750 hierarchical MQC

Question

Hello,
I have a requirement on the 3750 to shape traffic for Vlan 15 and 16 to 4 Mb while giving vlan 16 priority over vlan 15. Vlan 16 can suck all the bandwidth and make vlan 15 starve.
I implemented MQC with nested policied but didnt work. First I used the following:
class-map match-any VLAN15OR16
match vlan 15
match vlan 16
class-map match-any VLAN16
match vlan 16
policy-map CHILD
class VLAN16
bandwidth 4000
policy-map PARENT
class VLAN15OR16
shape average 4000000
service-policy child
when applying the service policy on the ES port it gives me the following error:
QoS: Invalid class policy CHILD
QoS: Invalid child policy CHILD
I replaced the "bandwidth 4000" with "priority" command then I got the following error when applying the policy:
"Priority is not allowed in logical class"
QoS with 3750 seems to work in a diff manner. Any suggestions on how to implement the requirement above!
Regards,
Ali

Answer 1

From QoS perspective, 3750ME is a special case.
You can imagine it better if you imagine 3750-24TS with a SIP-400-type router attached via 2Gbps internal etherchannel to it.
So you need to do QoS on 3750 part and on ES part separately.
Because ES ports are connected via internal VLAN they can only match DSCP in the packet, or copy COS to EXP. No special mathes are allowed on ES ports, since packet never carries information on what VLAN it originated from, what port, etc.
If you'll do QoS for ES ports just like for the router, matching DSCP/EXP, IP information, etc, and do standard "mls qos" for the standard ports, it will all work.
Just remember, ES facility is very limited performance-wise since it's a software platform. So the more functions you type, the slower it'll become, just like 7201 router.