How to prioritize bandwidth for WANs during data center consolidation

In today’s world of consolidation, perhaps no other IT infrastructure project occupies as much of a network manager’s time as data center consolidation. That said, how can we prioritize bandwidth for each segment of traffic across an enterprise wide area network (WAN) during a data center consolidation? Find out in this article.

Prioritizing bandwidth is a topic that network managers continue to struggle with—even when considering supporting production environments. As most network managers know, supporting production environments may not be fun, but it’s usually simpler than deciding how to carve up the bandwidth during a large project. That's because you should already have a history of data to help you fine-tune your operation. In today’s world of consolidation,...

perhaps no other infrastructure project occupies as much of a network manager’s time as data center consolidation. That said, how can we prioritize bandwidth for each segment of traffic across an enterprise wide area network (WAN) during a data center consolidation? That is what we will cover in this article.

From a technical standpoint, any discussion around bandwidth prioritization needs to start with quality of service (QoS), which is defined as the ability to give different priorities to specific applications that you are responsible for, which will guarantee a certain level of performance. You—the network managers—need to manage the delays, bandwidth and packet loss parameters on your network. The bottom line is that when you configure QoS, you must select specific network traffic and prioritize bandwidth according to its relative importance. Deploying QoS in your network will make network performance more predictable and bandwidth utilization more effective. Most of the better switches today allow for this capability. Before procuring your switched-based infrastructure, you must ensure that your hardware fully supports QoS capabilities.

During a data center consolidation, generally speaking, we’re trying to get by with less. This includes real estate—cutting back the number of physical computer rooms, servers, network devices and pipes. The process of prioritizing bandwidth is never easy. The approach I like to take is first to understand how much bandwidth is being allocated in your WAN today. Who currently defines priorities? Do people pay for priority, or is it based on the type of traffic? Let’s assume that you work with the business side of IT, which helps you determine the entitlements. This is actually the way it should be, as you don’t want to be in a situation where you as the network manager make these decisions in a vacuum. But being in this position means that you will be pushed and pulled by everyone, and making a decision about bandwidth prioritization will make you the hero to some and the enemy to others. This can be fun at times, but in the long run, it’s not worth the aggravation.

Once you determine bandwidth priorities, you can work with the network architects and determine what kind of pipes you will have in the consolidated data centers. At that point, you should provide a level of service at least as good as—or better than—you are currently getting. If not, you may run into performance problems that could put the entire data center consolidation project at risk. Why is this so? Because even though you may be purchasing new equipment (servers, routers, switches), if the network proves to be the bottleneck, the fingers will all be pointing your way faster than you can say “Help!” How can we prevent this from happening? It’s essential that you, as the network manager, work closely with everyone from the get-go. I’ve seen situations where the network team doesn’t get involved until it’s time to do testing on the applications. If you wait till this point, there will be little that you can do to fix the problems. If you get involved from the start, you can help architect the solution that will be deployed. At the same time, you can be involved in divvying up how the bandwidth priorities will be handled for your network segments.

Technology that helps prioritize bandwidth

Which technologies can we use to make bandwidth prioritization work better, besides QoS switches? WAN acceleration is important because it will better prioritize what limited bandwidth you have. Using WAN acceleration will allow you to reduce the amount of traffic sent across the WAN while delivering information locally where possible. At the end of the day, using WAN optimization controllers for application delivery will lower costs associated with app delivery, including facility fees and WAN bandwidth prices. Because your bandwidth is not unlimited, latency will take place over longer geographic distances. This is where network congestion can lead to packet loss.

Network monitoring is also an essential technology that will help you prioritize bandwidth. Business types need to understand precisely what is going on within the network. At the same time, they will help you determine the appropriate response time to make sure business needs are met. Network monitoring will also help you determine when your traffic is peaking so that you can make appropriate adjustments where necessary. Without effective monitoring, you won’t clearly understand whether the priorities you established are really in place.

The key to successful prioritization of bandwidth in a data center consolidation is to collaborate and communicate with everyone involved from the beginning. In this case, we’re not referring to technical communication but communicating with people. That means working with other folks in IT, working with the business side of your company, and with your ISP where necessary. The takeaway is that regardless of how technical you are, it is the soft skills that will ultimately allow you to succeed in that data center consolidation project. If you don’t take the time to make certain that you are communicating and working with the right teams, you are doomed to fail.

This was first published in August 2010

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