Faircloth Enterprise Applications Administration

The Definitive Guide to Implementation and Operations
1. Auflage 2013
ISBN: 978-0-12-407887-1
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 400 Seiten

Enterprise Applications Administration prepares you for the full breadth of work associated with administering large enterprise applications. This book provides essential information on tasks such as operating systems administration, network design, system architecture, project planning, working within a team, protecting the network, and how to keep applications up and running. The book effectively bridges the gap between what is taught in the technology-specific literature and the real world of enterprise application administrators. - Provides a general understanding of all key knowledge areas needed by enterprise application administrators - Bridges the gap between technology-specific literature and the actual work being performed by enterprise application administrators - Shows how to define and standardize processes and documentation to make enterprise application administration easier and more consistent

Jeremy Faircloth (CISSP, Security+, CCNA, MCSE, MCP+I, A+) is an IT practitioner with a background in a wide variety of technologies as well as experience managing technical teams at multiple Fortune 50 companies. He is a member of the Society for Technical Communication and frequently acts as a technical resource for other IT professionals through teaching and writing, using his expertise to help others expand their knowledge. Described as a 'Renaissance man of IT” with over 20 years of real-world IT experience, he has become an expert in many areas including Web development, database administration, enterprise security, network design, large enterprise applications, and project management. Jeremy is also an author that has contributed to over a dozen technical books covering a variety of topics and teaches courses on many of those topics.

Autoren/Hrsg.

Faircloth, Jeremy

Leseproben

Chapter 2 Networks
This chapter focuses on networking concepts and how to troubleshoot various aspects of networks. This chapter covers various network topologies and how each type fits into the corporate enterprise. Networking protocols and models, such as the OSI (Open Systems Interconnections) model and TCP/IP (Transmission Control Protocol/Internet Protocol) model, are discussed in detail including the various layers associated with the models and examples of the protocols used at each layer. Hardware and cabling are also covered including discussion of many of the common network devices, types of cables, and how connections are created between network devices. The second primary focus of this chapter is troubleshooting at various levels of the OSI and TCP/IP models. This troubleshooting includes manually simulating the same protocol usage that the enterprise application may perform natively using a variety of tools. Examples of various issues common within enterprise applications are given and techniques useful in troubleshooting of those issues are demonstrated. Keywords
Network; topologies; protocols; OSI model; TCP/IP; DHCP; DNS; FTP; HTTP; LDAP; SMTP; SNMP; SSH; Telnet; TLS; cabling; optical fiber; NIC; switch; router; load balancer; firewall; ARP; ICMP Information in This Chapter
 Network Fundamentals  Network Troubleshooting Network Fundamentals
The first technical area that we’re going to discuss is that of networking and its relationship to enterprise applications. As mentioned in Chapter 1, a system connected to no others is considered the most secure, but this concept could never apply in the world of enterprise applications. Therefore, it is important to understand the technologies used to network various components of the enterprise application together and how those technologies work. We will start with a discussion of network fundamentals. This will cover networking concepts, the most common protocols that you’ll be working with, and the logical and physical aspects of networking. The term “physical” in this case includes networking hardware, cabling, and even wireless communications. The hardware that we’ll discuss goes across the board from network interface cards (NICs) all the way to firewall devices. If you already have an understanding of these areas, then this will be more of a review than anything new. However, it is important to set an initial baseline of knowledge across all of these technical areas so that all enterprise applications administrators share the same core knowledge. Networking Concepts
When you consider the basic concept of networking, a network is really just a connection between multiple systems and devices that allows communication between them. This connection can be made via a variety of methods including copper wiring, optical fiber cable, or even radio signals (wireless). When working with enterprise applications, the complexity of a network grows tremendously, but you should always remember that at its core, it is simply communication between multiple systems and devices. Sometimes this simplification will help focus your troubleshooting as it’s very easy to become distracted by the sheer complexity of networking technologies and forget what it is that you’re really trying to accomplish. With that basic concept in mind, there are a few different types of networks that you need to be aware of. We’ll only discuss two of them here, as the third, metropolitan area network or MAN is not as commonly used as it once was. The first is a local area network or LAN. A LAN is a network that is isolated within a single building, floor, or limited area. It allows for communication between devices close by and no others. The second major network type is a wide area network or WAN. A WAN covers a much larger area and can cross a city, state, country, or even work across the world. The most common design is to have a LAN in place to handle local communication and then connect that LAN to a WAN in order to facilitate communication with nonlocal systems. A perfect example of this is as simple as the LAN in your home connecting to a WAN in order to gain access to the Internet. In the world of enterprise applications, you’ll typically deal with the structure of LANs connecting to WANs in order to provide global connectivity. Depending on the application design and needs, an enterprise application may be limited to only communicate within the boundaries of the LAN. However, with the global footprint of most large enterprises, it is much more common for the enterprise application to be available in multiple locations by routing its traffic over WANs to those locations. This communication may also be further limited to allow the enterprise application to be available across all of the company’s locations, but not be externally accessible to the Internet at large. We’ll talk about how this works as we discuss network designs as well as security. Topologies There are multiple network topologies that exist and are used under various circumstances. Depending on the network design, one or more of these topologies may exist in any given enterprise network. Each topology has its own benefits and detriments, therefore, it is pretty common for multiple topologies to be implemented in order to work around each other’s limitations. Network topologies can be categorized as being either physical or logical. In addition, a network’s physical topology may or may not match the network’s logical topology. Bus Topology The earliest network topology (outside of just connecting two systems together with wires) was the bus topology. In this topology, the network was effectively a single physical line with a bunch of systems tapping into it. All systems could “hear” all communications that were sent along the line. To connect to the network, it was as simple as adding a “vampire tap” which would penetrate the cable shielding and attach metal prongs to the copper wires in the cable or adding a break to the cable and doing a similar connection with metal adapters. A diagram of this network topology is shown in Figure 2.1. Figure 2.1 Bus topology. This topology allowed communication between all of the systems connected to it, but it had a couple very limiting factors. First, any break in the cable would disrupt communications network wide. Even if the break was intentional, such as modifying the cable to add a new system or removing a system from the network, the entire network would go down until the cable break was rectified. The network failure was due to two factors. First, obviously the systems on either side of the cable break would be unable to communicate. However, due to the very strict electrical tolerances required for the network to operate, even communications between multiple systems on the same side of the break would fail. A second limitation to this topology is the number of systems that can communicate on any given network bus. All network communication using copper cabling is based on electrical signals generated by the systems on the network. If too many systems are communicating using the same cable, the messages can conflict with each other and cause the receiving system to never get the message that was sent to it. Due to the way that networking software is designed (we’ll discuss protocols and software later), the sending system could, in some cases, identify that the message wasn’t received due to the lack of an acknowledgment and resend the message. This would cause even more network traffic and make the problem even worse. Eventually, communications on the network would slow down to a crawl or fail entirely. Even with those limitations, the bus topology is still in use today due to its speed and usefulness under specific circumstances. A logical bus topology means that when a system sends a message it will be received by all other devices on the network. Using the design shown in Figure 2.1, you will achieve a logical bus topology with the example of the use of a single cable. You can also get the same logical bus topology by using a physical star topology, as shown in Figure 2.3, with the central core being a device such as a network hub or repeater. Ring Topology Ring topologies are similar to a bus topology with the ends connected together so that it forms a ring. You can see an illustration of this in Figure 2.2. Ring topologies are not as common as they used to be, but they can still be found in some enterprise networks that have legacy systems in place. This means that some enterprise applications still have ring topologies as part of their overall network structure. In a ring topology, any given communication is passed around the ring from system to system until a system determines that the communication was intended for it and “pulls” the communication out of the ring. Figure 2.2 Ring topology. The ring topology worked well and eliminated a lot of issues around conflicting messages due to the way that the networking software utilized the topology. However, there were still some limitations to the topology that caused it to be less effective as the network grew. Since ring topologies are dependent on each system helping to pass messages along, problems with any system on the network could cause all communications on the network to fail. These system problems could be due to an actual failure or...