Qos Policy Shaping Allocations vs Link Speed

Answered Question
Feb 12th, 2009

Greetings im after some clarrification in how shaping on "class-default" is utilised. May be a silly question i just havent given it any thought before.

Based on a 10Mbit circuit of which i wanted to prioritise 2Mbit for voice and shape default traffic to 8Mbit would the following policy be correct or would i need to change the "shape average" statement to 10000000?


class Voice-Media

priority 2000

class Voice-Signalling

bandwidth 8

class class-default

set ip dscp default


policy-map 10M-ETHERNET-WAN-OUT

class class-default

shape average 8000000

service-policy ETHERNET-WAN-OUT


I have this problem too.
0 votes
Correct Answer by Edison Ortiz about 7 years 8 months ago

If you want to fully utilize the 10Mbps circuit, then the answer is Yes. You need to modify your shape average statement to reflect just that.

Please refer to the documentation for more info on the command:





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Overall Rating: 5 (1 ratings)
Joseph W. Doherty Thu, 02/12/2009 - 09:57

Just wanted to confirm you also realize you're shaping all traffic to 8 Mbps (assuming you use policy 10M-ETHERNET-WAN-OUT on the interface) and within that 8 Mbps you've allocated LLQ for 2 Mbps.

If the interface was 10 Mbps, you could use just policy ETHERNET-WAN-OUT (assuming you don't need to restrict all traffic to 8 Mbps).

Also, within policy ETHERNET-WAN-OUT, my belief is on most Cisco routers, FQ with class-default might preclude other non-LLQ classes from obtaining their minimum bandwidth. I.e. class Voice-Signalling might not obtain its bandwidth guarantee.


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