Bandwidth Utilization Avg or Max for capacity Planning best practice

[snarayanaraju]

Hello All - This is a conceptual or Non-Cisco product question. Hope you can help me to get this best industry practice

I am doing a Capacity planning for the WAN Link Bandwidth. To study the last month bandwidth utilization in the MRTG graph, i am seeing  two values

• Average
• Maximum.

To measure how much bandwidth my remote location is using which value i have to use. Average or Max?

• Average is always low eg. 20% to 30%
• Maximum is continuous 100% for 3 hour in 3 different intervals in a day and become 60% in rest of the day

What is the best practice followed in the networking industry to derive the upgrade size of the bandwidth by using the Utilization graph

regards,

SAIRAM

[Vasilii Mikhailovskii]

Hello.

It makes no sense to use average during whole day (or a month), as you do the capacity management to avoid business impact due to link utilization; and average does not help you to catch is the end-users experience any performance issues.

Typically your capacity management algorithm/thresholds are dependent on traffic patterns. As theses are really different cases if you run SAP+VoIP vs. youtube+Outlook. If you have any business critical traffic, you need to deploy QoS (unless you are allowed to increase link bandwidth infinitely).

So, I would recommend to use 95-percentile of maximum values on 5-15 minutes interval (your algorithm/thresholds will be really sensitive to pooling interval, so choose it carefully). After to collect baseline (for a month or so)  - go and ask users about their experience and try to correlate poor experience with traffic bursts. This would help you to define thresholds for link upgrade triggers.

PS: proactive capacity management includes link planning for new sites and their impact on existing links (in HQ and other spoke).

PS2: also I would recommend to separately track utilization during business hours (business traffic) and non-business (service or backup traffic).