Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Implement QoS to prevent new applic swamping network

Our organisation is shortly to implement a new centralised Microsoft Xchange mail service. This will service upto 13,000 mail clients across fixed WAN links (ranging in bandwidth (BW)from 1Mbps to 100Mbps). QoS is not used on the network at present. All routers and switches are Cisco (v12.2 and higher).

The concern is that when implemented this new mail service could potentially have an adverse impact on the network and all other WAN applications. So to prevent this occuring, QoS is being considered. There is no VoIP on network and unlikely to be for at least 2 years.

What would be the best QoS solution to deploy that will allow all existing applications to perform as they do now (ie prior to mail service roll-out), and to allow the new mail service to use all available BW unless there is network congestion. In this event this mail service should be 'marked' down to best effort?

Thanks in anticipation for any help and guidance.

kind regards

Mark

3 REPLIES
New Member

Re: Implement QoS to prevent new applic swamping network

Hello Mark,

You can take look at QoS basic setup from my previous post in the forum for reference. You can give the mail service a certain priority over any other apps by marking the packets like af21 (even af31) for data, and ef for voice.

HTH,

hieu

pls. rate post if it helps

New Member

Re: Implement QoS to prevent new applic swamping network

Hieu,

Thks for responding -- much appreciated.

Perhaps I didn't explain myself very well, the objective is to stop the new Xchange mail service from taking all available bandwidth and thus starving the existing application of bandwidth. We are only interested in applying QoS on the WAN links. What would be the best way to achieve this?

ie. Would it be best to classify the packets at the WAN routers by giving all applications (other than the mail service)a DSCP value of 5 (for example) and the mail service as 0 (Best Effort)?

New Member

Re: Implement QoS to prevent new applic swamping network

Hello Mark,

Marking all application packets as IPP 5 is not really a good way of setting up QoS because you'll overload the priority queues, and ends up starving the bw for everything else. It's best that you only classify certain critical applications as 5; all other applications that are not marked as 5 will go into a different class/lower priority that you specify. For example, if a packet is not matching the first classification, then it'll to the next class, and so on, and eventually end up in the default-class, which is set at dscp 0 by default.

In your situation, I think that the QoS should be applied to both sides of the WAN link to control the traffic.

Take a look at this link and look for "Enterprise QoS Solution Reference Network Design Guide Version 3.3". It'll give you some good idea of what you should do.

http://www.cisco.com/en/US/netsol/ns656/networking_solutions_program_category_home.html

HTH,

hieu

104
Views
0
Helpful
3
Replies
CreatePlease login to create content