Installation in OpenFlow

Welcome to OpenFlow

OpenFlow is an open interface for remotely controlling the forwarding table in network switches, routers, and access points. Upon this, researchers can build networks with new high-level properties. An example, OpenFlow enables more secure default-off networks, wireless networks with smooth handoffs, scalable data center networks, host mobility, more energy efficient networks and new wide-area networks. This is the OpenFlow tutorial flow:

Pre-requisites

Need a computer with at least 1 GB(prefer 2 GB) of RAM and at least 5 GB of free hard disk space (more is better). A faster processor may speed up the virtual machine boot time, and a larger screen may help to manage multiple terminal windows. you can install it for Linux, OS X and windows. But in here, i want to try explain instalation in Linux.

Install Required Software

You need to download these file on your Linux; virtual Machine (VirtualBox or else), an X server, and gnome terminal+SSH built in. You can download in here:

virtual_machine( OVF format 64 bit, mininet 2.0)

After finished your download, make sure that's working for you. 

Import Virtual Machine Image

If you download the .ovf image, you can start the VirtualBox, then click file, then import appliance and select the .ovf image that you downloaded. This step will take a while.

Or if you download the .zip file, from your terminal you can unzip the virtual machine, for example:

# unzip OpenFlowTutorial.zip

After that, you will need to complete one more step before you are done. Select your VM and go to the setting tab. Go to network, then adapter 1. Select the "enable adapter" box, and attach it to "host-only network". Note: for the first time, you may not have any "host-only network" yet. To have it, select File menu, then preference, then network and "add host-only network" button with default settings. And now you have already to start the VM. You can click start button to start it. In that VM window, log in with the user name and password for your VM. Note: username and password are mininet.

If you want to access the VM via SSH, you can start in the VM window with ifconfig to get the IP address your VM. The IP address could be eht0 with 192.168.x.x IP address. After that, open a new terminal, and access the SSH with; ssh -X mininet@VMIPaddress and after that enter the username and password same as before.

Review of wireless communication system

1. Representation of the cell coverage

• Cell, is the signal coverage
• Hexagonal cell is only used to simplify the depiction on the layout

in the picture above, you can see that in the real life, cell is very messy. Therefore, we use hexagonal model. In the wireless communication system, there are mobile station (ms) as a user, and base station (bts) as a transceiver. BTS has several type of antenna, such as Omnidertional, sectoring 120 degree, and sectoring 60 degree. The usefullnes of the sectoring pattern is like adding capacity and reduce interference. The Cell model, it has 4. Those are macrocell, microcell, picocell and femtocell.

2. Characteristic of cellular system.

• Frequency reuse
• Channel sharing
• Handover
• High spectral efficiency

Frequency Reuse

     The concept of frequency reuse allows the use of the same frequency in different cells, beyond the reach of interference. The parameter is a measure of power ratio signal/carrier to total interference power. Why we use frequency reuse? Because; limitation of frequency allocation, limited cell coverage area, raising the number of channels, from a cluster that contains several cell and co-channel intererence. 

Handover

     handover allows a user to move from one cell to another without any termination. Displacement occurs frequency/channel is automatically done by the system. Handover is a facility to guarantee communication continously if the costumer move from one cel to another.There are several type of handover; Intra-BTS handover, inter-BTS handover, inter-BSC handover, and inter-MSC handover.

1. intra-BTS: transfer relationship to a different channel on the same single base station
2. inter-BTS: transfer relationship between different base station in a single BSC
3. inter-BSC: transfer relationship between the BSC in a single MSC
4. inter-MSC: displacement relationship that occur in 2 different MSC

here is the mechanism of handover:

1. mobile station measure other cells
2. if better cell detected, handover initiated
3. mobile station handled by new cells, then handover completed

3. Cluster concept.

     Cluster contains several cells. K is representation of the number of cells inside cluster. 

the equation: K = i^2 + j^2 + i.j 

and to manage the frequency reuse, we need to know about the number of cells that separate the same frequency (we call as Co-channel Reuse distance ratio) and representated by Q. here is the equation: Q = (3.K)^0.5

thanks for visiting my blog.

The Brief of Software Defined Networking

Hai. In this time, i'm gonna tell you about a sort brief of Software Defined Networking. If you wanna know depthly about this, you can read from this link, or you can download the paper in here.
Okay, here we go!

Road to SDN

Designing and managing networks has become more innovative over the past few years with the aid of SDN (Software Defined Networking). This technology seems to have appeared suddenly, but it is actually part of a long history of trying to make computer networks more programmable.

Computer networks are complex and difficult to manage. They involve many kinds of equipment, from router and switches to  middlebox such as firewalls, network address translator, servver load balancers, and intrutions-detection systems. Routers and switches run complex, distributer control software that is typically closed and proprietary. The software implements network protocols that undergo years of standarization and interoperability testing. Network admininstrators typically configure individual network devices using configuration interfaces that vary between vendors-and even between different products from the same vendor. Although some network-management tools offer a central vantage point for configuring the network, these system still operate at the level of individual protocols, mechanism, and configuration interfaces. this mode of operation has slowed innovation, increased complexity and inflated both the capital and the operational costs of running a network.

But SDN, is changing the way networks are designed and managed. it has two defining characteristic. First is SDN separates the control plane(which decides how to handle the traffic) from the data plane(which forwards traffic according to decisions that the control plane makes). And second is SDN consolidates the control plane, so that a single software control programe control multiple data-plane elements. The SDN control plane exercises direct control over the state in the network's data-plane elements (routers, switches and middleboxes) via a well-defined API. the Openflow is a prominent of such an API. An Openflow switch has one or more table of packet-handling rules. Each rule matches a subset of traffic and performs certain actions on the traffic that mathes a rule, actions include dropping, forwarding, or flooding. Depending on the rules installed by a controller app, an openflow switch can behave as a router, switch, firewall, NAT or something.

Although the excitment about SDN has become more palpable fairly recently, many of the ideas underlying  the technology have evolved over the past 20 years. In some way, SDN revisits ideas from early telepony networks, which used a clear separation of control and data planes to simplify network management and the deployment of new services. Yet, open interfaces such as Openflow enable more innovation in controller platforms and applications than was possible on closed networks designed for a narrow range of telepony services. In other ways, SDN resembles past research on active networking, which articulated a vision for programmable networks, albeit with an emphasis on programmable data planes. SDN also relates to previous work on separating the control and data planes in computer neworks.

That is SDN. Thank you for visiting my page.

Movie review: Little Boy (2015)

Cast:  Jakob Salvati, Emily Watson, Tom Wilkinson, Michael Rapaport, Cary Hiroyuki-Tagawa, Kevin James, David Henrie, Eduardo Verastegui, Ted Levine.

Director:  Alejandro Monteverde.

Screenwriters:  Alejandro Monteverde, Pepe Portillo.

Producers: Leo Severino, Eduardo Verastegui.

Executive producers:  Mark Burnett, Ricardo Del Rio, Roma Downey.

Director of photography:  Andrew Cadelago.

Production designer:  Bernardo Trujillo.

Costume designers:  Rebecca Gregg, Laura Jean Shannon.

Editors:  Fernando Villena, Meg Ramsay, Joan Sobel).

Music:  Stephan Altman, Mark Foster.

Faith-based films have had an uneven record at the box office. The latest movie attempting to tap this market, Little Boy, is an often appealing, sometimes cloying nostalgic drama set during World War II.  Even with a strong cast and impressive production values, it faces an uphill battle to capture a sizable audience.

The production from Mexican director Alejandro Monteverde, who made the well-liked film Bella almost a decade ago, is designed as a fable about the power of faith to change the course of history.  (Roma Downey from Touched by an Angel and her husband Mark Burnett are among the movie’s executive producers.)  What makes it intermittently palatable even to non-believers is that it acknowledges some of the darker truths of the era.

The film is set in a fictional small town called Ohaire, California.  (It was actually shot in Baja).  Although it is a close-knit community, not everything is idyllic in Ohaire.  Our young hero, Pepper Flint Busbee (Jakob Salvati), is ruthlessly mocked by his classmates because of his diminutive stature.  The film is a pretty harsh depiction of the bullying he suffers.

The story gets under way when Pepper’s father and chief protector (Michael Rapaport) goes off to war and then is reported missing in action, probably a Japanese prisoner.  Pepper, who is nicknamed “Little Boy,” is desperate to have his father return, and the local priest (Oscar nominee Tom Wilkinson) encourages him to believe that if he has enough faith, he may have the capacity to alter the course of the war.

There are a few amusing touches that seem to corroborate the boy’s supernatural powers without falling over into religious drivel.  When Pepper sets out to demonstrate to the skeptical townspeople that he does have the strength to uproot the terrain, an earthquake appears to validate his claims.  Later the war comes to an end as a result of an atomic bomb given the name Little Boy (this is historically accurate, of course), and the townspeople genuflect before our pint-sized hero.

In addition to these touches of humor, the film benefits from an unexpected bit of social commentary.  One of the town residents is a Japanese man released from an internment camp.  He is ostracized by the community, but the priest convinces Pepper that as part of his spiritual journey, he must befriend the hated Hashimoto (Cary Hiroyuki-Tagawa).  Although Pepper resists the assignment at first, he does develop a tentative friendship with Hashimoto, which is threatened by the bigoted townspeople.

These lessons in tolerance may not be earth-shattering, but they give the film some moments of power and bite.  Nevertheless, the candy-colored fable is a bit too sluggishly paced to achieve any real drive.  The soft focus photography is pretty but too bland.  Although the film’s uplifting conclusion is predictable, there are some poignant moments before the glowing finale.

In addition to the always impressive Wilkinson, the cast includes another Oscar nominee, Emily Watson, who gives a grave and moving performance as the boy’s no-nonsense mother.  Kevin Jamesplays against type effectively as a lonely widower.  Young Salvati is clearly an amateur, but he makes a likable protagonist.  David Henrie as his more racist brother creates a convincingly complex character, and Hiroyuki-Tagawa contributes a dignified, unsentimental portrayal.

Technical credits are strong, even if the look of the movie is overly antiseptic.  In fact, the entire picture, though well-meaning and even thoughtful, is finally just a little too gooey.