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Qos deployment not achieving desired results

Posted on 2010-11-10
Medium Priority
Last Modified: 2012-05-10
Network setup – We are the hub to several remotes sites. Hub has 3 MB WAN connection. We host the central ERP system accessed by every remote site, as well as the central point for all email.
Testing involved one remote site with a 1024 WAN connection, all other remote sites have T1 WAN connection.
Using GRE over IPSec as well as Cisco WAAS throughout every site.
Problem – when email (no attachment size restriction), ftp, or sharepoint traffic traverse to WAN sites our ERP application (HTTP traffic) suffers timeouts.
Proposed solution – implement Qos to alleviate ERP timeouts and overall line degradation.
Set qos to mark ERP traffic as mission critical (DSCP af31) The WAAS is set to copy DSCP values.
Tried setting class to “priority bandwidth” – does not work since hub has 3MB connection and class will only be utilized when line is congested.
Set class to “percent” or “kbps” – “kbps” currently in place, dedicating 1533kbps to class marked af31
Matching packets now have a drop rate of 4 %, were as before we were not experiencing any drops.
End result is still that the ERP traffic gets degraded once the line is congested.
Desired result – Need dedicated response on line for ERP app regardless of amount of traffic that is on line.

Question by:ZachariaVinduska
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LVL 10

Accepted Solution

cstosgale earned 2000 total points
ID: 34106598
Ok, so you will need a policy map something like this:-

Central Site

class-map ERP
match ip dscp af31

policy-map CBWFQ
class ERP
bandwidth 1533

int s0/0
service-policy output ERP

Remote Site

class-map ERP
match ip dscp af31

policy-map CBWFQ
class ERP
bandwidth 512

int s0/0
service-policy output ERP

One thing that is really important about QOS, is you must apply it in BOTH directions. And of course you will need to mark the return traffic as well!

Make sure the packets are hitting the class.

Of course it could be the congestion is somewhere else in the network!

If you are still having issues, post the config of the hub and spoke routers.

Author Comment

ID: 34111960
Thanks for the response. The only problem with the bandwidth command is that it doesnt get utilized unless the line is congested. Since the Hub has a 3 MB and all the remote sites have a T1, the 3MB connection never reaches the max for the policy to take place. So we are using the "priority" command which is based off of a minumum guarantee. Here is what we have in place currently - (Note we are not marking on the remote side because the dscp value is being retained from the hub class JDE)

Hub site
policy-map JDEQOS2
 class JDE
  set dscp af31

policy-map JDEQOS-outbound
 class JDE-marked
  priority 1533

interface Multilink1
service-policy output JDEQOS-outbound

interface GigabitEthernet0/0
service-policy input JDEQOS2
Remote site
policy-map JDEQOS-outbound
 class JDE-marked
  priority 384

interface Serial0/0/0
service-policy output JDEQOS-outbound

LVL 10

Assisted Solution

cstosgale earned 2000 total points
ID: 34118508
Ok, the thing is te priority command will also police the traffic to 384 kbps. This means that any traffic above this rate will be dropped. The bandwidth command will prioritise the traffic above other traffic, even if you are not hitting line rate, at a certain point in time you may do, and therefore the bandwidth command will take affect. If you literally never hit line rate at the remote site or the central site you wouldn't need qos.

You have two options:-

1. Increase the amount of priority bandwidth, although be careful as this could starve other traffic

2.use the bandwidth command
LVL 71

Expert Comment

ID: 34840070
This question has been classified as abandoned and is being closed as part of the Cleanup Program. See my comment at the end of the question for more details.

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