How to determine bandwidth requirement for a link

[hgru]

Hi,

At the customer they asked me to monitor some links for userswitches for bandwidth usage. It happens that the total of these links have peaks to 300Mbps but that is the average op 15 sec. So what does this really say?

Is there a cisco supported methode like take all user links and multiply by 70% or so?

Thanks for all replies

[desai.jaideep]

Hi!

Your description is a little confusing that what u want.Please elaborate on line "user links and multiply by 70% or so? ".

Regards

JD

[balajitvk]

As he mentioned, your question is not clear.

U better use some b/w monitoring tool like mrtg to get the bandwidth usage.

But one cisco guideline is there to allot 75% of link bandwidth to user defined classes and to let other 25% of b/w for default classes. But i don't know whether it is relevant to your second question.

[hgru]

Hi,

Here is the setup as it is. There are 1000 users connected via 10 Mbps links to accessswitches. Those accessswitches have 1Gbps uplinks to a core switch. There are 100 servers connected via 100Mbps links to that core switch.

Now we want to move the 100 servers to a datacenter and connect the users to that remote datacenter via a WAN link. How do I determine what bandwidth that WAN would need to have.

One method is to monitor the links between the accessswitches and the core switch. I have done that and the highes peak of all these links added together at one moment in time was 300Mbps. But that was in a sample period of 15 sec. So does that help? I guess not because it could mean the there was a peak of 4500Mbps for a second and 0Mbps for the remaining 14 seconds of that 15 second sample period. So my guess is that monitoring a link for usage is no use unless you can have very short sample periods like 100ms or so.

So how do you determine the bandwidth requirement for that WAN link. One method would be add all the bandwidths of all the userlinks together. So that would mean the WAN link need to be (10Mbps times 1000 users) a 10 Gbps link. But that would be a bit excessive. So how do I make a good estimate for that WAN link. Could I take soming like 70% of that 10Gbps?

Or is the a better way?

Hans

[nayyarhak]

Hi

you can use CNA to monitor bandwidth being utilized on the aggregating links over a few days.

http://www.cisco.com/go/networkassistant/

From the data gathered you should be able to determine your minimal BW required for the users.

Rgds

nyr

[hgru]

Hi,

I already monitored the aggregation of the links. My problem is that I think this info is not usefull.

Hans