Five Class Model QoS Design?

Question

Hi all,
I work for a company with a medium-sized network. There are about seven MPLS WAN sites. One of them is a data-center. The rest are sites with mostly users.  The sites are dispersed through-out the continental United States.
Currently, the network is a basic data IP network with no QoS. There are a few projects slated for 2010. One involves implementing VoIP between just two sites. The other project calls for implementing IP-Video-Conferencing between the majority of the sites.
Should I start out with just a five-class model?
        - voice
        - call-signalling
        - IP video-conferencing
        - streaming video
        - default-traffic (all data)
Is there really need to break down the data traffic into QoS classes as well?
As always, thanks an advance for your help.
-Mike

Answer 1

msrohman wrote:Hi all,I work for a company with a medium-sized network. There are about seven MPLS WAN sites. One of them is a data-center. The rest are sites with mostly users.  The sites are dispersed through-out the continental United States.Currently, the network is a basic data IP network with no QoS. There are a few projects slated for 2010. One involves implementing VoIP between just two sites. The other project calls for implementing IP-Video-Conferencing between the majority of the sites.Should I start out with just a five-class model?        - voice        - call-signalling        - IP video-conferencing        - streaming video        - default-traffic (all data)Is there really need to break down the data traffic into QoS classes as well?As always, thanks an advance for your help.-Mike
Mike
The answer is  - it depends
Cisco recommend using the full model even if you don't actually use them or allocate bandwidth to them. That way you then don't have to go back and change all your configs if you need to add another class.
Weigh this against where you intend to use QOS primarily ie. on the WAN or LAN or both. The key thing is to talk to your WAN provider to understand what classes they provide ie. how many, how much each class costs etc. If they only provide 5 classes for example you could in theory simply use 5 classes internally and map these to the provider classes.
However there is nothing to stop you using 11 classes internally within your LAN and then mapping multiple internal classes to a single provider WAN class.
The other thing to bear in mind is the applications that make up the company data. Are there a few recognisable critical apps to the business of the company compared to the majority which are not critical. If so it may be worth reserving a class for these apps, even if you don't use it at the moment. If the time comes that the company then needs better performance for these apps you have already provisoned for it (makes you look good !), and you can simply map it to either a new provider class or an existing provider class with increased bandwidth.
It is basically a trade off between complexity of QOS configs and making things easier in the future and a lot depends on the apps that the company runs.
Jon