Energy-saving tips for business networks

Service provider takeaway: This tip offers 10 energy-saving techniques to reduce energy consumption and lower energy costs in general.

More on network energy Making the case for green networking

Rapidly increasing energy consumption costs are a serious problem for your customers. Servers and cooling equipment consume the largest fraction of data center power by far. Little attention is given to network components, but they also consume power and produce heat. Network integrators can provide a valuable service by analyzing and offering ways to lower network energy consumption, while resellers can replace old network hardware with new, more energy-efficient components. Use these energy-saving tips as a starting point. Each network is different, so not all will apply.

1. Shut off unneeded equipment. If server virtualization has resulted in fewer physical servers, the switch ports that supported the now removed servers are no longer needed. Staff reductions may have resulted in fewer workstations and therefore fewer switch ports are required. If some switches have a few active ports and others have unused ports, consolidate connections and unplug one of the switches.

2. Replace old, inefficient network hardware. Concerns about network energy consumption have led manufacturers to design higher-efficiency power supplies. Newer equipment consumes less power while delivering the same or improved function. Use the local cost of power to evaluate each potential replacement to calculate the payoff period.

3. Consolidate multiple small switches, which may have been purchased as the network grew, into a single larger switch. A single high-port-count switch is more energy-efficient than many smaller switches.

4. Calculate actual power requirements in switches with modular power supplies. Switches may have been overprovisioned when first installed, since power consumption was not a major consideration in the past. Power supplies operate more efficiently at a higher percentage utilization of available capacity. An unneeded supply increases available capacity, so at a given level of utilization, percentage utilization is lower, resulting in reduced efficiency. Put another way, using 40 watts of a 50-watt supply is much more efficient than using 40 watts of a 100-watt supply. If possible, remove one or more of the supplies. If the additional supply was put in place to provide redundancy, however, removing it may not be an option.

5. Review use of standalone VPNs, firewalls and DHCP servers. These standalone appliances have proliferated and each contains a power supply, takes up rack space and produces heat. Moving these functions into a modular switch can reduce power and heat.

6. Determine whether 100 Mbps is sufficient for workstation users. Most new workstations come with 1 Gbps Ethernet ports, which consume roughly 2 watts more than 100 Mbps. Configuring 1 Gbps on the workstation and on the corresponding switch port adds 4 watts to each workstation. While not significant for a small or medium-sized site, the unnecessary power use and heat can add up for a large site.

7. Evaluate use of Power over Ethernet (PoE). It is an efficient way to power IP phones, wireless access points and security cameras. It is not necessary on all switch ports, however, since it cannot be used to power workstations or servers. If PoE is available on all switch ports, make sure that it is configured off for ports that do not use it. When provisioning the power supply of a new modular switch, keep in mind that not all ports will require PoE.

8. Properly place all components to efficiently draw in cool air and exhaust hot air. While components may have been placed correctly when first installed, the addition or removal of adjacent equipment may have resulted in less efficient airflow. Use blank panels or move components to fill in gaps in racks that allow cool and hot air to mix.

9. Remove unnecessary terminals from switch console ports. Most switch management is done via the network, but a console port terminal may still be in place and powered up even though no longer needed. If for some reason it must be left in place, shut it off.

10. Conduct a component-by-component review of your customer's network to identify additional ways to lower energy costs. Many methods of achieving lower energy costs are common sense and will appear obvious once identified. While reviewing the customer's network, you can also suggest equipment upgrades and operational changes that will result in improved network operation.

About the author
David B. Jacobs of The Jacobs Group has more than 20 years of networking industry experience. He has managed leading-edge software development projects and consulted to Fortune 500 companies as well as software startups.