QoS Implementation questions

[johnramz]

Our infrastructure comprises CISCO 3845 routers, 3750 and 2960 switches. accross 3 offices connected thru a MPLS network.

We are currently facing performance issues in one of the offices. The main traffic from this office is: Outlook, Remote Desktop and Web traffic(80 and 443). We have not implemented QoS and I do not have expertise on it.

1- IS there any risk in turning AutoQoS in all of those devices I mentioned above to improve performance?

2-  I assume I could then later mark and classify traffic for certain applications if the AutoQoS needs to be tweaked?

3-  How could this QoS be consistent when going accross the WAN? How would I work this out with our MPLS provider? For example: I allocate so much bandwidth for video traffic and the provider would need to do the same, how do I approach this?

.

Please provide some guidance and whatever specifics you consider necessary

Thanks

John.

[Eugene Lau · Accepted solution]

Hey John,

As a first step, you can check out the Enterprise QoS Design guide:

http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoS-SRND-Book.html

(contact web-help@cisco.com if you have issues accessing links)

Two parts for consideration

a. Bandwidth management - do you need policies to manage the bandwidth? (this is pretty much a yes for WAN links)

b. How should you class your traffic? - QoS markings - such as CoS, DSCP etc There should be a consistent end-to-end schema

Thoughts on your questions:

1. I don't think Auto-QoS would help in the LAN, simply because the performance issues you are reporting are to do with DATA traffic. Typically, DATA traffic would be in the same class unless you start defining a QoS strategy to differentiate certain traffic.

If in the same class, it's really no different - and when you enable QoS, you actually have less buffers because the queues are carved up.

2. It would be better to define a strategy you would like to implement.

3. Typically, the WAN is the bottle neck so it would be a good idea to ensure there is congestion management on the WAN - such as CBWFQ/LLQ - Class Based Weighted Fair Queue / Low Latency Queuing (see link).

CBWFQ w/LLQ could ensure voice traffic is queued first, and you can have various traffic classes with allocated bandwidths. I would consider this a must.

4. RE MPLS provider should have the capability to Honor your QoS markings but there may be additional costs for SLA's. Best to check and they can provide guidance on how it will map into their network.

Under the MPLS VPN QoS Design segment - you can get a view of the QoS models and design considerations.

HTH

Eugene

[nicholas_ong · Accepted solution]

Hi John,

I would suggest this from a cost efficient manner.  Try setting up the QoS on your CPE first.  This would at least allow you to see if there are any improvement from the result of the implementation.  Usually there would be quite a bit of improvement when you prioritise Critical Traffic above the normal data traffic, it may be quite significant if your link is highly congested.  From there on then look at other options such as getting QoS option from supplier (costs may vary) and a bandwidth upgrade.  This is not an exact Science since it really depend on how your supplier does the pricing and what they are able to honor in their SLA.  However, if your connection is congested, then a bandwidth upgrade is quite the obvious choice.

Cheers.