Working Principles of the Layer 2 switch & Layer 3 switch | Network Administration

 Working Principles of the Layer 2 switch & Layer 3 manage switch  | Network Administration.

• Switches are Layer 2 device,
• Routers are Layer 3 device
• The new generation of Layer 3 switches route using hardware only.
• A switch will examine the incoming frame's MAC header to determine the physical address of the destination device.
• Whereas a HUB , simply repeats an incoming frame out of all its ports, the switch creates a virtual path to forward frames to the port. Where it knows the destination device exist.
• Switch can provide flow control to network traffic by temporarily storing frames in a buffer. 
• Switch can also generate BACK PRESSURE to cause transmitting device to wait long enough for the switch to deal with backlogged traffic. To create back pressure, the switch broadcast false collation detection signals to cause network interface card to back off.
  

 

How to configure the MRTG to Poll multiple devices in Linux Operating System ?

 Getting MRTG (Multi Router Traffic Grapher) to Poll multiple network devices.

The Fedora Core MRTG installation process create a CORN file named /etc/corn.d/mrtg . This file tells the corn daemon to run MRTG using /etc/mrtg/mrtg.cfg file every 5 minutes to poll your network devices. You can configure MRTG to poll multiple devices, each with a separate configuration file.

1. Create a new configuration file using the steps from the previous section, choose a file name that is not mrtg.cfg

2. Add a new MRTG lene in / etc/corn.d/mrtg for each new configuration file you create.

0-59/5 **** root env LANG=C /usr/bin/mrtg  /etc/mrtg/mrtg.cfg

0-59/5 **** root env LANG=C /usr/bin/mrtg /etc/mrtg/dervice1.cfg

0-59/5 **** root env LANG=C /usr/bin/mrtg /etc/mrtg/device2.cfg

3.Run the indexmaker command, and include all of your /etc/mrtg configuration files.

4. Other versions of Linux keep their MRTG corn entries inside /etc/corntab file. Edit this file using the same syntex.

Now , restart the corn demon as 

root # service cornd restart.

Free software for Monitoring Network Performance - MRTG [Multi Router Traffic Grapher]

 MRTG [Multi Router Traffic Grapher]  is a Free Software for Monitoring Network Performance in Graphical form. Here we will discuss the installation process of this free software in Linux distribution.

For Linux System ,we need to install the following software

1. MRTG [latest version]
2. SNMP
3. Apache Web Server 

MRTG

How to Configure the MRTG ?

When MRTG's rpm is installed, it creates a directory called /etc/mrtg.

To create a replacement, default /etc/mrtg/mrtg.cfg configuration file for server , follow these steps,

1.Use MRTG's cfgmaker command to create a configuration file named mrtg.cfg for the server. Using a read only community string of craz33guy. Place all data files in the directory /var/www/mrtg.

root#cfgmaker --output=/etc/mrtg/mrtg.cfg

--global"varkdir: /var/www/mrtg" -ifref=ip

--blobal 'option[.] : growright, bits

crez33guy@localhost

NOTE :- -if ref=ip cfgmaker command option instruct MRTG to use the interface's IP address as the title for each graph.

2. Edit /etc/mrtg/mrtg.cfg, and remove the section related to interfaces you don't need to monitor. A certain candidate would be the virtual lookup interface LO: (127.0.0.1)

3. Run MRTG using /etc/mrtg/mrtg.cfg as your argument 3 times. You will get an error for 2 times, as MRTG tries to move old data files, and naturally the 1st time when it runs the MRTG , it has no data to move.

root# env LANG=C /usr/bin/mrtg /etc/mrtg/mrtg.cfg

-> give this command 3 times

4. Use MRTG's indexmaker command to create a Web index page using your new mrtg.cfg file as guide.

root# indexmaker --output=var/www/mrtg/index.html   /etc/mrtg/mrtg.cfg

5. MRTG is run every 5 minute by default, and the file that governs this is /etc/corn.d/mrtg. To work correctly edit this file, replacing all occurrence of /usr/bin/mrtg with env LANG = C /usr/bin/mrtg.

Do's and Don'ts of Structured LAN Cabling Network

 What is Structured Cabling & Why it is used ?

"Standard " is to define a method of connecting all types of vendors voice & data equipment, over a cabling system that uses a common media, common connectors and a common topology. This means that a building can be cabled for all its communications needs without the planner or architecture even having to know what type of equipment will be used.

There are three main cabling standards.

• EIA/TIA 568 A ---> American standard and was the first to be published on 1991.
• ISO/IEC 11801 ---> International Standard.
• CENELEC EN 50173 ---> European Standard (British version is BSEN 50173) .

TERMS:

1. Cable Tie
2. Patch Panel
3. PVC pipe of Casing
4. IO Box
5. RJ45 connectors
6. Cat 5e/6/7 cable
7. Wall mount Box.

HDSL Modem Connection & Configuration Details with Diagram

 High Bit Rate Digital Subscriber Line or HDSL Telecommunications Technology is used to transfer data over Private Copper Network or E1 digital Subscriber Line. The Download Speed of the HDSL line is 1.54 Mbps and the Upload speed is is 1.54 Mbps.

HDSL One Pair Modem Connection Diagram