Abstract—Importance of network management is described. Network management problems are classified. Major classes of network management problems such as aligning code and managed data, scalability problems, management of large network elements, development problems, changes of MIBs, MPLS-related problems and the lack of quality professionals are considered. Possible methods of addressing these problems are suggested for each of the classes of network management problems. Future network management challenges and approach to overcoming them are discussed. .
Index Terms—network management, network development, scalability, SNMP, MIB, NMS
Networks play a crucial role in modern society and serve for business as well as for personal use. The process of managing networks becomes more and more complex in the course of time due to various factors, such as growing range of services, increasing bandwidth, greater complexity of network structure, existence of large network elements, use of devices relating to various layers of OSI model etc . A network should maintain flow-through automation of such FCAPS areas as fault detection, provisioning, billing, checking performance, upgrading and repairing the network .
Virtually every company managing a network might have to face problems related to the above-mentioned factors.
The purpose of this paper is to classify network management problems according to their sources and develop recommendations for addressing these problems. This paper does not focus on technical issues solely; problems related to human resources, development and future potential are also considered. The paper is intended to benefit first of all network administrators and managers, as well as network developers. At the same time, the classes of network management problems mentioned below can help anyone planning and maintaining a network to make it more effective currently and in the future. .
II. Network management problems
Effectively managed network creates a number of competitive advantages such as decreased cost of ownership, improved efficiency, high quality of communications and data exchange and time-effective procedures. Such a network can even serve as a revenue enabler and can generate additional market opportunities . However, in the process of development and growth network management can generate technical challenges, integration concerns, operational and organizational challenges and business challenges. Below the most common classes of network management problems and possible solutions are described.
A. Aligning code and managed data
A network management system is aimed to operate multiple network agents in order to connect multiple network objects, to keep track of NE changes and timely apply new changes. As a result, massive volumes of data are generated. One of key advantages of SNMP agents is the overhead between the agent and the object ; however, this property creates a challenge when the size and complexity of networks increase. For complex networks, it is not reasonable to re-request full information about the object, and the network management problem is in the balance of existing data, actual picture of the network and the messaging load on the network.
Network managers should realize that the gap between actual state of the network and its MIB representation is inversely related to the quality of the NMS . At the same time, getting full and actual information about the NEs can result in overloading network channels. The purpose of network management in this case is to find the optimal balance of data and code (agents) and develop the network towards reducing the above-mentioned gap.
B. Scalability problems
All networks currently have to face the problem of scalability. According to , “a scalability problem occurs when an increase in the number of instances of a given managed object in the network necessitates a compensating, proportional resource increase inside the management system”. In other words, if the number of connections or circuits grows similarly to the square of the number of locations or sites, scale problems, or N2 problems arise .
Example of N2 problem is illustrated by Fig. 1.
These problems are especially common to unidirectional or simplex-channel networks. Other scalability problems are generated by increasing requirements to bandwidth and switching capacity. In addition to this, scalability problems arise at the development level: in a complex and diverse network NMS might have to read too many MIB entries and run low of resources . These issues are solved by using new type of MIBs or by data compression.
Other scalability concerns relate to storage solutions, setting firewall rules, managing routers (the use of static routes and access control lists are key concerns), security and application management.
In order to avoid scalability problems, it is recommended to switch to newer versions to protocols, equipment or technologies (e.g. from VPN layer 2 to VPN layer 3). For developers, it is useful to utilize more effective MIBs and compression software. To address other scalability problems, storage area networks (SANs) and intelligent network management components for traffic and security analyses should be used .
C. Managing large network elements
As requirements for the networks increase, more complex equipment is commonly used such as denser switches, routers etc. These devices allow to reduce costs, save space, power consumption, cabling requirements and management time . Most of these devices also offer a larger set of features. At the same time, these devices also create new challenges. The majority of them require special management skills and represent critical network points with regard to failures, therefore posing greater backup requirements. It also becomes more difficult to locate the causes of problems because of denser communication flows.
NMS management professionals and developers have to construct networks in order to maintain effective interaction between devices working at different network layers. For example, ATM protocols operate at layer 2 , while IP-based objects require the convergence of layer 2 and layer 3.
To address these problems, network management professionals have to approach new equipment with certain criticism and evaluate potential problems before introducing new network devices. In addition to this, they have to monitor network performance in a more accurate way and should be open to training in order to gain skill with the new equipment.
D. Development problems
Network management poses a lot of problems for NMS developers. First of all, the code should be optimized and the number of changes to existing systems should be minimized, since most changes require reconsidering all layers of FCAPS model. Distributed networks create logistical challenges and might cause performance bottlenecks . NMS developers have to handle such network problems as database problems, corruptions of MIB table, crashes of client applications and exceptions of SNMP agents.
Another set of problems is created by the need for backwards compatibility of new technologies and previously created software (e.g. migration to MPLS). Elements of NMS development include analysis of data, design of classes implementing necessary NMS features, selection of middleware and even use of low-level code in the parts of the code where execution speed is critical.
In order to address these problems and to develop effective NMS, the following steps are recommended :
– The developers should study the basics of the technology they are managing
– EMS should be used to realize how the network elements provide the features of the technology
– MIB browser gives the possibility of viewing the relevant MIBs and optimizing MIB table
– Basing on the previous 3 stages, it is possible to create samples of code using the new technology for the MIB objects.
E. Changes of MIBs
MIBs are key components of NMS. Selection and organization of MIBs poses a number of challenges. The structure and scheme of MIBs should be optimized, but it is necessary to store critical information in several places for maintaining reliability. Thus, network management professionals have to determine optimal balance between storing additional information and minimizing the MIB network scheme.
If new technologies have to be added to network elements, changes of MIBs might be required. NMS should support different versions of MIBs when network upgrades are performed. NMS should give the possibilities of managing firmware and perform backups of old versions of firmware. In order to maintain compatibility, it is recommended to store old objects in the MIB if there is such a possibility; moreover, old objects should not be modified for the purpose of backward compatibility . Removal of MIB objects can only be done in extreme situations, since various software might rely on the existence of these MIBs. Finally, network managers and developers should ensure that integration of new MIBs into the NMS can be done automatically (manual changes should be eliminated).
F. MPLS problems
Various network problems can arise at MPLS level. It is necessary to perform traffic engineering instead of increasing bandwidth as a passive solution to traffic bottlenecks. Rising popularity of WANs can create another bandwidth bottleneck. One of possible solutions is using a proactive QoS and providing “chunks of bandwidth”  to developers. MPLS routers should be able to form a “link/state database of the network”  which would also include analysis of allocated and available bandwidth. Traffic prioritization should also be used to regulate network load; traffic marking is another effective approach – in this case every package is marked with appropriate class of service, and no additional microflows of data are required within the network.
For MPLS, scalability problems are also actual. The increase of the number of network elements results in rapid growth of MPLS tunnel table, and SNMP agents have to face the N2 problem. One of the solutions allowing for greater scalability is to create another table containing only those MIB objects which have changed. This will also increase the number of rewriting operations in the NMS, but SNMP agents will become more effective.
G. Lack of qualified professionals
The diversity of the network management problems described above shows that building and developing network management systems has become a highly complex task. Network management professionals have to be familiar with the majority of existing network technologies, hardware, software and protocols, programming and script languages, design and upgrade of databases, deployment and installation issues, security requirements, MIB design etc . Moreover, a successful network management professional should possess a certain mindset focused on creative problem solving, taking ownership of problems, minimization of changes and high aptitude for testing .
NMS developers should also be able to acquire domain expertise quickly, master new technologies and specifications, embrace emerging requirements and functionality of the networks (in comparison with existing requirements) and should be able to make linked overviews of new network features. For NMS development, short cycles of development are common, which creates more pressure for the developers. Even operational skill sets for network management are rather scarce, since network operators should have domain knowledge and experience with various devices and network layers, should be able to manage multiple networks and have a solid understanding of the FCAPS framework in addition to numerous network technologies.
This challenge is one of the most difficult to address since the roots of it are outside the scope of a particular organization. Successful network management professionals are likely to “grow out” of the network operators and engineers, provided that they are properly trained and motivated, and have vast possibilities for mastering new technologies. The same can be stated about NMS developers – the basis of their success is ongoing development, training and huge interest to new network technologies and solutions.
This paper outlined a number of the most important network management problems. The majority of these problems are related to increasing requirements to networks, growing number of new technologies and the need to maintain backwards compatibility. In the future, different network management problems can arise. Most likely, they will be centered around the limitations of new technologies (such as WAN bandwidth and security) and new perspectives of network management such as emerging systems of provisioning, inventory management, CRM, management of IP telecommunication applications etc . Broadband multimedia services and e-commerce are potential sources of new network management challenges as well .
The lack of quality professionals is the greatest challenge which should be addresses in the first place. Companies, unions and governmental organizations should address this issue and stimulate the development of network management professionals. Such approach will allow to address new network management challenges and will contribute to the overall technological progress.