Author: T. Y. Fam
Research Assignment

Abstract

SNMP is currently most widely used network management tool when managing a large scale networks. However, there are many limitations while using SNMP which will be discussed in this paper. To overcome SNMP weaknesses, this research paper will introduce Web services based network management tools to give a contrast between them. Web services also can be implemented as an additional layer stay on top of SNMP.

1.� � � Introduction

1.1 SNMP
In the early of 1990, Internet has grown rapidly every year in the area of IP Networks, and how to manage those networks. SNMP (Simple Network Management Protocol) which works alike Manager and Agent mechanism is the current dominant network management tool. The advantage of SNMP is mainly due to its simplicity. However users have found out its limitations such as inefficient in configuration management operations, application development complexity and lack of scalability in large scale networks. A better technology has to be introduced in order to replace or enhanced the current technology.

SNMP design is based on MIB (Management Information Bases), it contains objects identifiers which organized hierarchically. MIB will be accessed by different protocol such as SNMP. Complete MIB is a list of characteristics of the specific device [5]. Devices can be a router, server, switch, computer, printers and any hardware that’s need to be monitored. An agent will be installed as a software module which resides in the device. Agent will provide required management information which is in SNMP protocol format. A manager is the main component in a network management system; it can be considering as client in a client and server architecture. Manager control management operations, applications and traps from different agents [5].

1.2 XML
In 1998, the World Wide Web Consortium (XML) has standardized a markup language called Extensible Markup Language (XML). In term of flexibility, because XML documents such as Document Type Definition DTD and XML can be transferred to the internet, it is easer to manage compared to SNMP. The development cost of XML can be low because it comes with many free APIs which can be used for accessing different types of XML data. The structure of XML is simple, where XML documents store all the data and XEL (Extensible Style Sheet) will

be used to create query to retrieve the relevant data. XML is able to transfer large amount of data with only one single XML document [3].

All of these advantages mentioned above were able to solve the problem of scalability and efficiency of the current management system using SNMP management systems. Most of the current hardware devices have SNMP agent installed on them, therefore a gateway to communicate between SNMP and XML need to be installed to allow communication between them [3]. XML is highly scalable in bulk data processing; therefore it is suitable for bulk configuration management such as network management.

2. Scalability and Efficiency of SNMP

While the SNMP simplicity may be good in managing network systems but the increasing of internet or network systems caused the SNMP management system failed to process all the tasks quick enough to maintain the performance of efficiency in a long term basis. Management data increase when the Internet and agent required managing increased [2]. The increase of agent means the increase of IP Routing table, TCP connection table, accounting table and others. The current SNMP management cannot process these tasks efficiency with a few reasons such as the increase of network overhead. Network overhead is a network management traffic that generate on top of user client. It will obviously affect the client network speed when a large overhead traffic increases continuously due to the increasing of required data management. Latency in network management should be keep in the minimum level, the increase of latency will greatly reduce the whole network performance by using SNMP because the time to recover a problem may be increase when the network size increased. SNMP does not using a distributing processing mechanism while processing its task, thus increase the cost of hardware resources such as processor and memory. SNMP also limits the flexibility of management level due to the centralized mechanism. Data from all clients are gathered into one segment point. The scalability and efficiency of SNMP communication protocols can be improved by using XML network management tool [2].

3. XML

3.1 Introduction
XML is simple yet powerful enough because it is using HTTP structure. Data are stored in a XML document which can be exchanged easily over the internet. XML works differently compared to HTML, XML separates data and expression, thus information can be expressed in different methods. XML document is able to define data structures by using Data Type Definition in an XML document. XML also fully accessible by any programs that support Document Object Model structure either for storing or retrieving data [2].

In network management system, XML is good in transferring network data which will be processed by network management tools. Data can be modelled with the modelling function provided in XML function, which mean that SNMP data structure can be

read by XML easily. XML then transfer the retrieved data via HTTP mechanism which is already standardize in World Wide Web. In terms of compatibility, XML can transfer data between any software and hardware that support HTTP. It is easy and low cost when developing XML because XML comes with standard free APIs and development tools. During data transmitting, XML data only required one document to store all the information. This obviously solved the scalability and efficiency of SNMP network management system [2].

3.2 XML in Network Management
Most agents used in the current industry uses EWS (embedded web server) to communicate with their device. In this research criterion, XML will be implemented to retrieve information from devices through the agent which has embedded web server in order to pass data between XML and devices. The figure below shows the step by step on how the manager is able to manage a device within agent and device by using XML translation.

In example (A), a manager request a data from agent and the agent reply with a message with a list of managers back to the manager. In example (B), manager tries to control agent and tell the agent to add a new user into the system. Manager Operation=“Add” used to give an operation action called Add, while “<UserName>James</UserName>”is the new user that need to be added into the system. Example (C) shows that agent can communicate to manager when there is a fault alarm such as device’s cooling fan failed to work properly. The manager client will receive “<FanStatus>Fail<FanStatus>” and translate the information to the manager and seek for instruction to solve the problem. Each action A, B and C are similar in methods where sender using either POST or GET method to retrieve data and “HTTP/1.1 200 OK” to reply with the status “OK”.

3.3 Reasons for using HTTP medium
There are a lot of benefits by using web-based network monitoring. Manager can connect to the system at any browser enabled computer around the world. No additional cost is required for accessing into the network management system. Previously, SNMP tools required user to install software in order to use it. Different software vendor may come with different licensing prices. Installing software on new machine often required new license which increase the management cost. Furthermore, HTML browser works perfectly with XML technology without any conflict [4].

4. Gateways

4.1 Introduction
Trap, Set and Get are common function in SNMP communication methods. They work similar to the methods of XML. By using XML as a communication level, it can solve the limitations of SNMP network management system. Because SNMP is already widely used in current network system, it is very hard to replace every system into XML based network management system. In order to solve the limitations, a gateway needs to be implemented for XML to communicate between SNMP based agents and XML based manager. In [2], a gateway was introduced that relays data between SNMP based agent and XML based manager. XML based manager will pass the data with XML document over HTTP; while SNMP based agent will pass their data via SNMP protocol. The proposed gateway will convert all the data and relaying the XML and SNMP protocols [2].

4.2 SNMP - XML Translation Algorithm
Before any conversions it is important keep the data and structure of the original form correctly. Each line of SNMP data will be converted into XML element. Any clauses will be converted into XML element’s attribute. In figure 2 shows an example of how each node will be converted in XML format [2].

Syntax analyser will read the SNMP and check for errors. It will also remove any unwanted data such as comments and definitions. When error occurs, it will return an error message to the user. Every successful generated table will contains a list of nodes with object. Object will be classified into different classes. XML Schema will generate XML schema documents from the node table. In this scenario study, the author uses JAVA programming language to implement the SNMP – XML translator [2].

5. Web Services

5.1 Introduction on WS
XML is a high level semantics system that works great in bulk processing. Some devices vendor such as CISCO, they have already built-in XML capabilities into their system which accelerate the development using XML mechanism. In some cases, XML is usually build in a distributed behavior where allows remote communications between manager and agent. Web Services is a distributed object technologies that works together with XML technology. WS has become one of the proposed network management tools because of a number of benefits. Web Services is a W3C standardized technology which greatly reduces the complexity during implementing process. Open standards technology often comes with free associate tools to help accelerate the development process [1].

Programming language tools that support Web Services such as JAVA, Microsoft .Net, C++ and others obviously increase the potential of Web Services portability. Web Services network management system can be easily integrated in different platforms which developed in different languages [1].

5.2 Web Services Implementation
The easier way to implement a Web Services management system is illustrate in figure 3.

In figure 3, Web Services was implemented on top of SNMP enabled devices. The XML / SOAP interface receive commands from Manager, and then transmute it over the IP Networks. Embedded SOAP engine will transfer command into SNMP commands such as GET, SET or TRAP which mentioned in section 4 [1].

5.3 Advantages
Recently, XML based network management system has solved the limitation of SNMP network management in term of operations. XML have higher level semantics compared to SNMP, thus is it more efficient in processing bulk configuration. XML also can handle complex management data due to the easy to generate data structure. Again, XML is a standard from W3C technology and they come with different supporting tools such as XSLT which can transform XML document into different queried output. In terms of security, internet browser has increase the security level in recent years. Browser now supports sophisticated checks on security files and security in scripting language [4].

6. Conclusion
Web-based network management system will become more popular and more efficient in the coming years. XML technology was getting better everyday; APIs are provided for free which greatly reduce implementation cost. When using web-based as a communication tool, security is very important as internet is open to the public. Good security systems such as Virtual Private Networks need to be implemented in order to provide a secure communication tunnel between client and server.

However, web-based monitoring applications may increase the efficiency of current SNMP systems but it will not completely replace the whole SNMP system anytime soon because most of the devices in the market now are building for SNMP protocol. Only new and limited devices come with build in XML mechanism. Before that, the current approach will only be implemented on top of SNMP enabled devices. Gateways translator as mentioned above are required to allow communication between XML and SNMP devices.

References
[1] John, S., Dimitris, A. (2007), “Web services-based network management: approaches and the WSNET system”, John Wiley & Sons, Inc. USA, Vol. 17, Iss.1, PP 33-50

[2] Jeong, H. Y., Hong, T. J., James, W. H. (2003), “Development of SNMP-XML translator and gateway for XML-based integrated network management”, John Wiley & Sons, Inc. USA, Vol.13, Iss.4, PP.259-276

[3] Shaik, S., Mohammed, H. S. (2006), “Distributed XML-based network management using JPVM”, John Wiley & Sons, Inc. USA, Vol.16, Iss.4, PP.263-277

[4] Ron, D. J. (1999), “Why web-based network monitoring? Leveraging the platform”, John Wiley & Sons, Inc. USA, Vol.9, Iss.3, PP.175-183

[5] Wikipedia, “Simple network management Protocol” 2007; http://en.wikipedia.org/wiki/SNMP

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