Politics are a part of virtually all network initiatives, and nowhere is that more evident than with QoS. While most network managers concede that QoS is a prerequisite for real-time applications such as VoIP and interactive video, many of those same managers are reluctant to embrace QoS for data applications because of the political pitfalls. This reluctance is starting to impede business productivity and is increasing bandwidth costs.

A network manager is often stretched in many directions by department heads who try to use their clout to get their applications pushed to the top of the heap.

The benefits of QoS are real: More predictable performance, more efficient use of bandwidth, and more detailed control of network resources. However, because QoS has the ability to provide better (or worse) service to specific applications, the stakeholders of those applications have a vested interest and, therefore, the politics also are quite real.

To effectively implement QoS, network managers need to develop not only a strategy for deployment, but they must also develop a communication plan to set the agenda and reduce the political pressures that have derailed many QoS initiatives. To help with this effort, consider the following:

1. Set realistic expectations.
Create a "QoS 101" presentation or primer document that provides a high-level overview of QoS: What it is (and isn't), how it works and the benefits to the organization. QoS is a complex topic, and creating this primer will help business managers understand the technology and provide a common language to ensure that the IT staff is delivering a consistent message.

2. Clearly determine the objectives.
Best practices suggest that certain applications should be identified and given priority. In other words, these traffic flows should be "promoted." Another school of thought suggests that because there are specific applications that create network congestion (such as Microsoft's SMS and FTP), it is more efficient to identify these flows so that they can be de-prioritized or "demoted." From a practical standpoint, a combination of the two approaches likely will be used. For example, a leading financial services company initially focused on protecting its network by "demoting" non-interactive traffic and bulk file transfers. With those applications pushed into the background, the company then could "promote" its revenue-generating applications, which were more interactive and transaction-oriented.

Regardless of the initial approach, the critical success factor is to ensure that the overall objectives for QoS are well documented and endorsed by an executive sponsor before deployment.

3. Classify traffic based on technical profiles.
Most networks are shared resources that provide connectivity to multiple business units. If you ask any business manager, he will say that his application is mission-critical and should receive preferential treatment. This is the point where politics can overwhelm the project. To promote objectivity and consistency, terms like mission-critical and best effort should be avoided.

Instead, the focus should be on creating profiles based on the technical aspects of the traffic flows. These profiles should include the service-level requirements for each application (such as protocol, packet size and bandwidth) as well as its ability to deal with the effects of congestion (for example, delay, jitter and packet loss).

4. Build a strong cross-functional team.
Implementing QoS is not for network novices. With tools like Weighted Fair Queuing, Random Early Detection and Link Fragmentation at their disposal, it is critical that engineers understand the function and interaction of each tool before developing QoS policies. Those who handle operations and capacity planning will need to interpret traffic flows at a more detailed level than before to determine if the QoS policies are having the desired effect. To promote interdepartmental communications and knowledge transfer, a virtual team consisting of members from each area should be formed. Also, sufficient training dollars should be included in the business case for initial implementation.

5. Start small and get a quick win.
After the QoS policies have been developed, a small number of sites should be selected for a controlled introduction. Generally speaking, QoS will have the biggest effect on sites that match the following criteria:

-- Slower speed WAN links (less than a T-1).

-- Periods of transient congestion (not chronically oversubscribed).

-- Combination of interactive (foreground) and non-interactive (background) traffic.

The initial sites should match these criteria and have the backing of the largest stakeholder. Have network-monitoring tools in place to analyze the traffic flows and modify the policies if they produce unexpected results. After IT validates the policies with live traffic, communicate the results to the stakeholders and the executive sponsor.

At some point, all enterprise networks will have to provide differentiated services and doing so on a large scale is a significant undertaking. By proactively developing a deployment strategy and communication plan, network managers can set the agenda, reduce the political pressures and ultimately provide more predictable delivery of all traffic throughout the network.

Cornum is senior manager of strategy for the consulting practice of Calence.