Cisco QoS config  w/ ASA 5510, Catalyst 3560, and 2960G

Posted on 2011-03-03
Medium Priority
Last Modified: 2012-05-11
Hi Cisco Gurus,

Here's my current network config:

10x10MB internet connection <==> ASA 5510 <==> Catalyst 3560 48-Port Switch (LAN) <==>  Catalyst 2960G (Servers)

I'm doing extensive research on implementing QoS to maximize my network bandwidth efficiency since I have many remote users doing file share, VPN, and VOIP while my LAN users require heavy internet and media streaming.

As I'm doing my research, I'm a bit confused on the following:

1) Do I need to set QoS Policies only on the ASA or on the ASA and switch(es) -- what's the best practice?
2) I'm unsure on how to calculate the following to configure:  
    a) For Priority Queing: tx-ring limit size & priority queue size - provide example for voip requiring 1000K worth of bandwidth
    b) For Policing:  Maximum Rate limit & Maximum burst size - provide example of restricting http/https traffic to max 50% of bandwidth

Please elaborate on how to calculate, cli command, and the rhyme and reason to it...thanks!
Question by:jetli87
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LVL 28

Expert Comment

ID: 35037202
QoS policy should be end-to-end.  (ASA and the switches, in your case.)

2.  b) I would recommend that you use shaping and not policing.  Policing will drop all sessions if you get above the limit (because the router just stops transmitting).  Shaping will start dropping a few packets in order to slow the flow of data, without dropping everything all at once.

I'll have to get back with you on exact commands.  Can you show me what you have so far?

Author Comment

ID: 35065911
Hi thanks for the response.

I've actually done more reading and research so I understand the logic a bit better then when I originally posted this question.

With that said though, I just need a bit more clarification on Tx-ring limit and priority queue size and how to calculate what's the approriate setting for a specific scenario.

LVL 28

Accepted Solution

asavener earned 1500 total points
ID: 35066029
I'm not familiar with the TX-ring limit.... what is the command to which you are referring?

As for VoIP, since you're unlikely to use up the entire bandwidth with VoIP, I'd suggest just setting up a priority queue for voice.

Author Closing Comment

ID: 35234042
Did not provide indepth analysis on the question.

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