01-14-2015 09:14 AM
Hello,
I have been tasked with implementing a QoS policy not designed by me, and i do not have the freedom to just change it, but i would like to understand what/why my issue is going on, so that i am better informed when i try and relate what i am seeing back up the "chain".
I have been trying to read up on how Cisco routers do what they do in these situations, but i am getting a little wrapped around the axle, and it has not quite locked in yet... so, please bear with me.
The Reader's Digest scenario is:
GigE LAN, with dual DS3 WAN (MPLS) circuits (some sites has only a single DS3, but it happens at both):
The QoS policy looks something like this:
priority percent 10
shape average percent 27
bandwidth remaining x
bandwidth remaining xx
bandwidth remaining xx
bandwidth remaining x
bandwidth remaining 25
I am seeing bursts of output queue drops. Deeper checks show that the largest amount of drops occur in the last class, the class-default. There are small amounts in one other queue, but the ratio is nominal.
I probably sound like an idiot, but i am still shuffling through the ACL assignments, etc...
Thank you in advance for any time and assistance provided.
~ john
01-17-2015 03:27 AM
H John,
shape average percent 27
Why are shaping at 27% of the total BW? If you have a 45Mbps you are shaping at near to 12Mbps. Anything above that BW will be queued and therefore will have the chance to get dropped.
CF
01-20-2015 05:11 AM
Hello Cisco Freak,
I appreciate you taking the time to answer my question. Unfortunately i have not been given the "why", only the "do"... and that has left me with dealing with the mess once Operations began noticing the issue.
The 12% you mention, would this be in addition to the 10% set aside for the priority percent? (For a total of approximately 16mbps).
Your answer is a bit helpful, but the default queue... is this just because it is the last bucket of the queues?
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