Regular Expression for matching an ip address

What is ip address ?

=>An IP address is an identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination.The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address.

Regular Expression (explained in TCL)

Program :

set a "192.168.10.25"

if {[regexp {^(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$} $a]} {

puts "its an ip address"

}

Explanation :

[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5] : it matches any value from 0 - 255

^(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.) : it matches the first byte i.e 192.

^(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3} : it matches 192.168.10.

New WLAN management solution

Industry's best Wi-Fi management solution

Cloud powered, supports leading enterprise access points

 

Looks Promising ! Nira Wireless is taking big steps in the field WLAN management.

Cloud powered management of your Cisco, Aruba or Motorola Access Points.This way they are not tied to one vendor while moving from 802.11n, to 802.11ac WAV1 and WAV2 access points. Also, unlike vendor provided solutions, Nira's product are not partial to any particular vendors APs.

Looking forward for hands on with the tool and will update the experience.

http://www.nirawireless.com/features

Control Plane & Data Plane

The control plane is the part of a network that carries signaling traffic and is responsible for routing.

The data plane (sometimes known as the user plane, forwarding plane, carrier plane or bearer plane) is the part of a network that carries user traffic.

 Let's consider the example of  the management of public transportation of a city.

Before we send bus drivers out, we need to have a plan.

Control Plane = Learning what we will do

Our planning stage, which includes learning  which paths the buses will take, is similar to the control plane in the network.   We haven't picked up people yet, nor have we dropped them off, but we do know the paths and stops due to our plan.  The control plane is primarily about the learning of routes.

In a routed network, this planning and learning can be done through static routes, where we train the router about remote networks, and how to get there.   We also can use dynamic routing protocols, like RIP, OSPF and EIGRP to allow the routers to train each other regarding how to reach remote networks.   This is all the control plane.

Data Plane = Actualy moving the packets based on what we learned.

Now, after the routers know how to route for remote networks, along comes a customers packet and BAM! this is were the data plane begins.   The data plane is the actual movement of the customers data packets over the transit path.   (We learned the path to use in the control plane stage earlier).

 

Fun Programming: For Network Engineers

Sometimes its a tedious task to manually configure CLI's on the network devices.
Imagine how much time it will take to configure say near to 100 ACL or VLAN and then configuring each of them.Well the question is not about how to improve your typing skills indeed its about leveraging programming/coding skills for these simpler task to save time and be more efficient.I realize most networking folks aren't going to run out and start doing Tcl programming.

As its almost everywhere "Programming: An Essential Skill For Network Engineers" http://ubm.io/1pKNb9f

WHY not to start with some basic scripting to make life easier :

Cisco has embedded TCL in CISCO IOS.The Tcl interpreter is invoked by typing "tclsh" at the enable EXEC mode prompt. The Tcl shell attempts to interpret a command as a Tcl command. If that fails, it then tries to interpret the command as a Cisco CLI command.Your Tcl program can issue EXEC or CONFIG mode commands. This allows you to write Tcl programs to build menus or walk junior staff through configuration tasks.

Command	Purpose
ios_config "command" "sub-command" Example: ios_config "interface Ethernet 0" "description this is a demo"	Run a Cisco IOS configuration command (sub-mode commands must be quoted on the same line as the main configuration command)

Example:

Configuring 50 VLAN.

1. tclsh
2. for {set I 1} {$I < 51} {incr I} {
ios_config "vlan $I" "exit"
}
3. exit
4. show vlan

Yipee , its done .

Shannon's Law

Shannon's Law, formulated by Claude Shannon , a mathematician who helped build the foundations for the modern computer, is a statement in information theory that expresses the maximum possible data speed that can be obtained in a data channel.

The law, formulated by Claude Shannon of Bell Telephone Labs, says that the data capacity, in bits per second, is a function of the bandwidth, the signal strength, and the noise in the channel.

 c = b log2 (1 + s)

No practical communications system has yet been devised that can operate at close to the theoretical speed limit defined by Shannon's law.

But DIDO allows each user to communicate, in theory, up to the full Shannon limit of the channel.

Distributed-Input-Distributed-Output (DIDO) wireless technology is a breakthrough approach that allows each wireless user to use the full data rate1  of shared spectrum simultaneously with all other users, by eliminating interference between users sharing the same spectrum.

WiFi Site Survey

 

Many network managers will simply install extra WiFi APs as a quick fix to increase the wireless coverage capability. However, that often does little .

There are three different types of site surveys widely used in the industry: passive site survey, active site survey, and predictive site survey.

A passive site survey tool listens to existing access points and, outside your managed infrastructure, for signal strength, interference, and AP coverage. Passive site surveys, in which surveyed WiFi adapters don't need to associate to the AP or SSID, give a good overall picture of the RF characteristics of existing wireless networks.

During an active site survey, the survey WiFi adapter is associated to the AP(s) and exchanges packets. This allows gathering of very detailed information. Actual network traffic, throughput packet loss, and physical (PHY) rates can be captured. Active surveys are commonly used for new WLAN deployments.

A predictive site survey is performed without any type of field measurements. It uses RF planning software tools that can predict wireless coverage of the APs. To perform this site survey, a floor-plan drawing (AutoCAD, JPEG, PDF) is a must-have. Predictive site surveys are used when the site or building is not yet built and are helpful for budgeting purposes.

The goal of all of these wireless site surveys is to provide detailed information that addresses the site’s radio frequency coverage. Before implementing or attempting to optimize a WLAN, you’ll want to understand all the possible areas of interference, AP placements, power considerations, and wiring requirements that are needed. A wireless site survey can provide all of this information and more, so you have the tools you need to design, implement, and optimize your wireless network.

Which is faster 40Mhz vs 2x20Mhz ?

Well the question is whether should we use one AP working on 40 Mhz channel width or should we have 2 AP with each channel width configured to 20 Mhz.

The answer is somewhat clear that 2 AP will provide good redundancy and better management.

Points to Consider:

1. CPU Utilization will be less and get shared on 2 AP , better than loading single AP with more clients which will result to High CPU Utilization and degrade AP performance.

2. Contention mechanism would allow better chances to the clients.

3. The more degrees for freedom offered in network solution, the more resilience and quality of user experience is likely achieved.