Lesson 8—Networking BASICS1 Networking BASICS Managing a Local Area Network Unit 2 Lesson 8

Lesson 8—Networking BASICS2 Objectives List the proactive steps to be taken to keep a network server in operation. Tell how server performance can be monitored. Explain how SNMP and network monitors are used. List and describe the features of common network troubleshooting tools.

Lesson 8—Networking BASICS3 Managing the Server This is one of most important jobs of a network manager. Take steps to prevent errors. Monitor for problems.

Lesson 8—Networking BASICS4 RAID Redundant Array of Independent Drives Fault-tolerant hard drives There are six common levels.

Lesson 8—Networking BASICS5 RAID Levels RAID 0 – Striping across drives. RAID 1 – Disk mirroring and disk duplexing. RAID 2 – Uses error correction code (ECC). RAID 3 – Uses parity error checking.

Lesson 8—Networking BASICS6 RAID Levels

Lesson 8—Networking BASICS7 RAID Levels

Lesson 8—Networking BASICS8 RAID Levels RAID 4 – Larger stripes. RAID 5 – Divides parity checking across drives. Dual-level RAID – Combines multiple hardware RAID arrays. Not all levels are fully supported.

Lesson 8—Networking BASICS9 Backups Backups copy data to another media and store it in a secure location. Optical discs (CD-ROM and DVD) are not often used. Archive bit – This is set when a file is backed up and cleared when a file is changed. It is important to test backups.

Lesson 8—Networking BASICS10 Types of Backups Full backup Differential backup Incremental backup Copy backup Daily copy

Lesson 8—Networking BASICS11 Uninterruptible Power Supply The UPS supplies power to the server if electrical power fails. Power conditioning – Ensures a correct and constant level of power. Surge protector – Prevents spikes from reaching the server.

Lesson 8—Networking BASICS12 Uninterruptible Power Supply

Lesson 8—Networking BASICS13 Virus A virus instructs the computer to perform an operation without the user’s consent or knowledge. Viruses are destructive or non- destructive. Viruses are replicated primarily by .

Lesson 8—Networking BASICS14 Types of Viruses Macro – Attaches to application program and executes. Polymorphic – Changes appearance each time it replicates. Stealth – Hides its presence from detection.

Lesson 8—Networking BASICS15 Monitoring Server It monitors the performance of the server’s CPU. It can be done at one time or as an average. When the CPU is constantly over 90%, that indicates that the server is overloaded.

Lesson 8—Networking BASICS16 Monitoring Server

Lesson 8—Networking BASICS17 Server RAM RAM is divided into page frames. The NOS pages out frames when they are no longer needed or when a frame is needed for other data.

Lesson 8—Networking BASICS18 Page Faults Page fault – Swap data back into RAM page. Soft page fault – Data retrieved from RAM. Hard page fault – Data retrieved from hard drive.

Lesson 8—Networking BASICS19 Page Faults

Lesson 8—Networking BASICS20 Monitoring Network Performance The entire network must be monitored. There are a variety of hardware and software tools available.

Lesson 8—Networking BASICS21 SNMP Simple Network Management Protocol Part of TCP/IP suite Gather data about network performance Software agents sent to management information base

Lesson 8—Networking BASICS22 SNMP

Lesson 8—Networking BASICS23 Network Monitors There are software packages to monitor network health. They identify late collisions, jabber, and negative frame count. They are available for all operating systems.

Lesson 8—Networking BASICS24 Protocol Analyzers They are also called packet sniffing tools. Promiscuous mode – Captures all network packets. Data can be filtered.

Lesson 8—Networking BASICS25 Hardware Tools Multimeter – Measures characteristics of electric current. Cable checker – Determines status of cable. Time domain reflector – Sends signal and records return.

Lesson 8—Networking BASICS26 Summary The role of managing a computer network is the job of the net- work manager and involves two major tasks: taking necessary proactive steps to prevent problems from occurring and watch- ing for symptoms that may indicate something on the network is not right. If a symptom reveals a problem, the problem must be fixed immediately before things get worse. A variety of preventive measures can be taken to make the server as stable as possible. Fault-tolerant server hard drives are based on a standard known as RAID (Redundant Array of Independent Drives). The fundamental idea behind RAID is to install several disk drives inside the server. This array of disk drives appears to the server as a single drive. If one of the drives fails, the other hard drives keep the server and network functioning.

Lesson 8—Networking BASICS27 Summary (continued) There are six common levels of RAID: RAID 0 through RAID 5. Yet RAID does not diminish the need for data backups. Data must be copied regularly to another media and stored in a secure location. Although CD and DVD technology is often used for backups of data stored on client computers, it is rarely used for data backups of network file servers. There are five basic types of backups: full backup, differential backup, incremental backup, copy backup, and daily copy. Many network managers perform a full backup once a week and a differential backup once a day.

Lesson 8—Networking BASICS28 Summary (continued) An uninterruptible power supply (UPS) is an external device located between the outlet for electrical power and the server. The primary purpose of a UPS is to continue to supply power to the server in the event the electrical power fails. Yet the UPS is much more than a large battery. UPS systems interface with the NOS on the server to ensure that an orderly shutdown will occur and “clean” the electrical power before it reaches the server. A computer virus is a computer program that instructs a computer to perform an operation without the user’s knowledge or con- sent. Computer viruses can be either destructive or nondestruc- tive. Computer viruses are usually designed to replicate and quickly infect other computers.

Lesson 8—Networking BASICS29 Summary (continued) Managing the server involves not only taking proactive steps to prevent problems from occurring, but also monitoring the server so any problems that do occur can be quickly identified and solved. Monitoring the performance of the server includes watching the CPU, hard drive, and RAM. Monitoring the per- formance of the CPU can reveal whether the system is training under the load of the network or has power to spare. Programs that monitor the CPU utilization are found on almost every NOS.

Lesson 8—Networking BASICS30 Summary (continued) Compared to the CPU, RAM is the second-most important component in a file server that should be closely watched. Because RAM is so vital to the operation of the server, a server that lacks sufficient RAM can cause all network users to wait unnecessarily long periods of time for their programs to load and for the server to answer their requests. Another important component of the server that needs to be monitored is the hard drive. The total amount of free disk space left on the hard drive is especially important. If the amount of free disk space is 20 percent or less of the entire hard drive, more free space must be found.

Lesson 8—Networking BASICS31 Summary (continued) An array of tools can be used to monitor the performance of the network. The Simple Network Management Protocol (SNMP) is part of the TCP/IP protocol suite. SNMP allows computers and network equipment to gather data about network performance. In addition to SNMP, other software packages can be used to monitor the health of the network. Known as network monitors, these packages provide a wealth of network statistics. Protocol analyzers capture packets so they can be analyzed. They also translate the contents of the packet from a form the computer and network uses to a form humans can read.

Lesson 8—Networking BASICS32 Summary (continued) A variety of hardware tools can also be used for digging deeper to discover the source of a network problem. A multimeter is a tool that measures the characteristics of an electric current. A cable checker is used to determine whether a cable can send and receive packets. A cable tester performs the same function as a cable checker, but also provides additional results. A time domain reflectometer (TDR) is a sophisticated device that sends a signal down a cable and then records the return of the signal. Handheld network analyzers combine the best features of protocol analyzers, multimeters, cable checkers and testers, and TDRs into a single small device.