1. Introduction

In this tutorial, we’ll study the differences between Network Management System (NMS) and Element Management System (EMS). Both terms are related to network management but have different purposes and properties.

First, let’s clarify why these systems are needed to allow a deeper understanding. Next, we’ll define each one of them. Finally, we’ll systematically compare EMS and NMS.

2. What’s the Need for EMS and NMS?

A computer network offers a variety of services for connected users and their end devices. These network services are offered by processes running on some hardware. Each node (hardware) of the network that runs some service (or part of it) is called a Network Element (NE).

In today’s world, organizations are highly dependent on their networking services. Therefore, keeping these services working fine is synonymous with running the business. This can only be achieved if the NEs are well-managed.

However, due to the variety and complexity of modern NEs, this is not an easy task to do. To address the related issues in a cost-effective way, we need some tool that offers good user interfaces and hides the complexity of the network and NEs. This is the role of NMS and EMS.

Now, let’s look at these two systems in more detail.

3. EMS

An Element Management System (EMS) is an application that can manage NEs individually, allowing for granular control and monitoring of specific elements. More specifically, we can say that an EMS is responsible for the FCAPS of NEs. FCAPS is an acronym for Fault, Configuration, Accounting, Performance, and Security.

As illustrated in the figure below, each EMS typically manages one or more NEs. Also, NEs managed by the same EMS are similar in terms of type and features. Thus, it’s common for an EMS to be able to manage a family of NEs from the same provider:


An EMS performs FCAPS functionalities by collecting and processing data from NEs. However, it handles the collected data on a per NE basis, not including functionalities that process aggregated data from different NEs.

As a result, EMS provides simplified interfaces and valuable information on NEs. These features are very useful for network administrators when managing the NEs individually. Also, the EMS features can be consumed by network-wide management systems, as we’ll see in the next section.

4. NMS

A Network Management System (NMS) is an application that can perform FCAPS of NEs in a correlated manner. Therefore, an NMS manages NEs by considering the data of individual NEs and the aggregation of all data.

In addition, NMS is able to understand the connections and relationships among NEs. Thus, an NMS can perform FCAPS functionalities from a wide perspective of the network.

Typically, an NMS manages NEs by consuming the features provided by the respective EMSes. The figure below illustrates this kind of management as the NMS communicates with EMS 1, 2, and n. This approach enables NMS to manage completely different NEs:


However, in some cases, an NMS can collect data directly from NEs. In the figure above, this situation is exemplified as the NMS communicates directly with NE n-2.

Because of its properties, NMS is able to manage an entire network or at least a large part of it. Hence, the NMS allows network administrators to manage NEs from a wide perspective, not having to deal with the NEs’ particularities.

5. Comparison

Let’s directly compare these two systems by examining some key points.

5.1. Support for Multiple and Different NEs

An EMS can manage one or more NEs. However, it’s very common for an EMS to only support NEs of the same (or very similar) type. So, we need different EMSes to manage distinct NEs (especially if they’re from different vendors).

On the other hand, an NMS can manage multiple NEs of different types. Thus, we often need only one NMS to manage or at least a large part of an entire network.

5.2. Data Source

EMS collects data directly from the managed NEs. To do this, the EMS needs to know the features and communication interfaces provided by each NE for its FCAPS management.

In contrast, NMS typically obtains data from NEs via their respective EMSes. Nevertheless, an NMS can also collect data directly from NEs. But in this case, it needs to be familiar with the NE specificities.

5.3. Data Aggregation and Correlation

EMS considers only individual data for each NE. For this reason, we say that EMS doesn’t understand the connections and relationships between NEs.

On the other hand, NMS aggregates data from multiple NEs and correlates them. Thus, an NMS is able, for example, to detect that a failure event in a given NE caused a failure in another one.

By doing so, NMS enhances the information produced by EMSes to provide a more complete view of how NEs work together. In addition, the correlation of data from different NE enables NMS to understand the connections and relationships between the NEs.

5.4. Summary

The table below summarizes the main differences between EMS and NMS.

Rendered by QuickLaTeX.com

6. Conclusion

In this article, we learned the differences between NMS and EMS. We’ve seen that while EMS manages NEs from an individual perspective, NMS is able to aggregate and correlate data from multiple NEs. Therefore, EMS gives us detailed management of NEs, and NMS provides broad management of the network as a whole.

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