Capacity Control

Network resources can be categorized into two types:

         - Network devices like routers, switches (layer 2, layer 3, layer 4), firewalls, load balancers, traffic shapers, caching servers, remote access servers (popularly known as RAS) and the new breed of boxes that are called as VPN concentrators.

         - WAN bandwidth (the most important and precious network resource)

It is important that these network resources are sized optimally during the initial design stages. After the network is implemented and production traffic starts flowing, comes the important challenge of running the network without downtimes (either for the network devices or the WAN links) and any sort of degradation in response times. Capacity control plays a very important role in achieving this objective consistently. Depending on the size of the network, there can be a dedicated Capacity control planning team comprised of two or three senior members.

As we have seen earlier in this series, the Network Management control serves in collecting vital real-time statistics related to the network health. This will be useful in drawing up baselines and trends that are related to the current network usage.

The Capacity control team assimilates these inputs from the Network Management Control (NMC) process and chalks out the relevant action plans. For example, a particular WAN link of 2 Mbps capacity is being reported by the NMC process to be under-utilized (say, less than 512 Kbps). There can be various corrective measures like downgradation of the E1 link to a fractional E1 link, extending the observation period for the link utilization by a month for traffic patterns/changes, review the network topology for logical changes like parenting smaller nodes for consolidating WAN bandwidth and ultimately, surrendering of the link itself!

The Capacity control process correlates the input from the NMC process along with the necessary business inputs on projected growth/expansion. The Capacity control team arrives at the final decision on the corrective measure after weighing the inputs carefully.

This process is applicable for network devices too.

An effective Capacity control process will ensure optimal provisioning and utilization of network resources. As the results of this process has a direct impact on costs, its importance can only be over-stressed!.

- Badri Narayan