Kibbles & Bytes Blog

  • Advanced Networking: OSI Layers Overview

    In the beginning of networking, when ARPANET was still in its infancy, the collaboration that was necessary to make communication work smoothly between computers was built upon the RFC (Request for Comment) model. In building ARPANET, many of the most talented computer scientists of the time (circa 1969) started creating informal documents to share ideas on how networking should function and how connections should be managed.

    To make networking universal and non-proprietary, the OSI model was established. OSI (Open System Interconnection) is considered to be the basis of TCP/IP and networking as it is deployed today. The OSI model consists of seven layers describing the functions and elements of a network and how they should all interact. The seven layers are Physical, Data Link, Network, Transport, Session, Presentation and Application. Each layer plays an important part in how data is sent and received on our networks of today.

    The first layer of the OSI model, Physical, describes the aspects of the physical connection, be it voltages over copper to wavelength of light emitted in fiber-optic connections. It is responsible for establishing connections and terminating them too.

    Layer 2, the Data Link layer, is responsible for the transmission between network nodes. The Data Link layer of the OSI model has two sub-layers, LLC and MAC. The Media Access Control, or MAC sub-layer, makes sure that the received frame was meant for a specific machine by verifying that the MAC was encoded within the frame. The LLC (Logical Link Control) sub-layer provides the tolerance for running several different protocols on one network medium. It also helps provide flow control as well as error management.

    The Network Layer is responsible for the routing of data, logical addressing, datagram encapsulation and it too helps in error handling. Logical addressing in the network layer is based on the IP protocol from the TCP/IP suite. The addressing provided by IP (Internet Protocol) is also used in the routing at this layer.

    Layer 4, Transport, makes sure data can be sent reliably from the sending node to the destination. It is at this layer that acknowledgement, or ACK, becomes part of the communication. An ACK is simply the step of the receiving node sending an acknowledgement that it has received the complete message. If no ACK is sent, depending on other factors, the sending node may choose to retransmit the message.

    The Session Layer is the 5th layer of the OSI model. The Session Layer controls the timing of transmission and who will send versus who will receive at any given time. It is responsible for the integrity of the connection between the nodes. The Session Layer determines speed of data transmission based on other attributes from lower layers. Depending on the physical connection, it is the session layer that will decide if transmission will be simplex, full duplex or somewhere in between.

    Layer 6, Presentation, is responsible for the how the data is encoded. Presentation takes the information from the Application Layer (layer 7) and breaks the data down into ASCII or EBCDIC language. It is the layer responsible for the syntax of the communication, as well as the encryption and compression of the data to be sent over the network.

    Lastly, the Application Layer is the function of what you want the network to do. The protocols of HTTP, FTP, SMTP, POP and many others determine what data will be assembled by the lower levels and sent across the network to provide the outcome you plan for.

    While this is by no means a comprehensive list of what each layer does, it is because of the RFC and OSI model that these defined layers were developed to regulate and standardize communications over networks.

    “__Image source__”:http://studynet-work.blogspot.com/2011/09/open-systems-interconnection-osi.html

  • Apple Announces OS 10.8 "Mountain Lion"

    Apple announced last week that the next release of OS X, dubbed “Mountain Lion,” will be released this summer. Ever lessening the gap between OS X and iOS, Mountain Lion adds a few features and streamlines several others.

    One example is iCal, which will be renamed Calendar. Rather than have a To-Do list as part of Calendar, Apple has added Reminders and moved the To-Do list there. Now there is a one-to-one match between where your information is stored on your iPhone and on your Mac. Same goes for Notes; no longer part of Mail, Notes is now its own application similar to how it is in iOS. You don’t have to search for “where did my notes go?” after syncing your data.

    Another addition is Messages, which updates iChat to include iMessage functionality. You will be able to chat with iOS users directly using the same program you use to chat with AOL, Jabber, Google, and Yahoo! subscribers. Further, messages will be synchronized across devices, so there’s no more “where was that message with that phone number?”

    Game Center has been added to OS X, so you have the same achievements and leader boards as on your iOS device. More Mac game developers are coming up with versions for both platforms, so now you will be able to share your scores between them.

    Finally, a sharing feature many have been looking forward to: AirPlay Mirroring. If you have ever used an iPad to share your screen with a second generation Apple TV, Mountain Lion will give you this same feature.

    Releasing a new OS so soon after Lion seems to be setting a new trend–is Apple now going to release smaller, annual updates? Instead of releasing a new operating system every two years for $129, perhaps they are now going to update more frequently for $29.99 (but don’t quote me on that). Using the App Store for distribution certainly makes it easier to obtain the software–no more driving to the local store or ordering online and waiting a few days–as well as lessens the environmental footprint.

  • So, it’s that time of year again…the time of year that I __may__ look forward to more than the when the issue of Cat Fancy hits my doorstep. I am talking about the Hippo’s annual Best of voting for 2012.

    We here at Small Dog feel that we do the best of anyone in the Manchester, NH area for service and support. We would love to have our loyal readers know that their vote does count and that if you have had reason to use our award-winning service–and you feel that we deserve some recognition–we would love to have you fill out one of the surveys and fill in our name on entry #125: “Thing we forgot to ask about.” Please put “Best Computer Service Shop – Small Dog Electronics” and then the fine people at Hippo Press will do the rest.

    “*Fill out the survey here.*”:http://www.hippopress.com/best-of-2011

    I do hope that we can win, but I know that I can only do one entry (that’s what the rules state), so I will have my cat do one as well. He has never had anything serviced there, but don’t tell them that.

    Thanks for your support! And now on to the technical stuff…

  • Calling all Switchers…and anyone else who wants a great deal on Microsoft Office: Mac 2011! Get our Home and Student OEM version of…

  • Essential Apps for Your Mac

    My mind is in Spring Cleaning mode right now (maybe because this weather is ridiculously unseasonable?). In between scrubbing the wet paw prints…

  • Weekly Apple News Recap | 2/13-2/17

    Apple had some notable news this week (but no, the iPad 3 isn’t out yet): Apple Releases Mountain Lion Developer Preview Apple announced…

  • Using social media? Have you connected with us on “*Facebook,*”:https://www.facebook.com/smalldogelectronics “*Twitter*”:http://twitter.com/hellosmalldog or “*Google+*”:https://plus.google.com/104375478293479731740/posts yet?

    Aside from getting glimpses into life at Small Dog, we often feature contests and tips for your Mac. Do it!

    Thanks for reading Kibbles & Bytes, and I’ll be back with you again next week.
    _Kali_

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    * Automatic daily backup to the cloud
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    * Renew your online backup after 1 year at “*cloudbox.lacie.com*”:http://cloudbox.lacie.com

  • SPECIAL: Wi-Drive? Because You Gotta!

    Wi-Drives are pretty cool, especially if you have an iPod touch, iPhone or iPad. *For a limited time, the 16GB Wi-Drive is $60 off and the 32GB Wi-Drive is $40 off regular pricing.*

  • Kingston Wi-Drive Review

    Kingston’s Wi-Drive is a new portable (and affordable) storage and sharing solution for iPod touch, iPhone and iPad. The Wi-Drive is roughly the size of an iPhone and comes in 16GB and 32GB storage capacities. It creates a small Wi-Fi network that you can access through their “*free Wi-Drive app*”:http://click.linksynergy.com/fs-bin/stat?id=19XpSnZWhPI&offerid=146261&type=3&subid=0&tmpid=1826&RD_PARM1=http%3A%2F%2Fitunes.apple.com%2Fus%2Fapp%2Fwi-drive%2Fid440013905%3Fmt%3D8%2526uo%253D6%2526partnerId%253D30 (opens iTunes Store), allowing you to view and share anything that you have stored on your iOS device.

    The app also has a built-in media player that streams the music, movies and more that you have stored, so you don’t have to worry that it will take up valuable storage space on the device itself. It supports a wide variety of video, audio and file formats as well.

    My one complaint about the app is the fact that you can’t load content __to__ the Wi-Drive from your iOS device directly. All content needs to be loaded via USB from a computer and then streamed to your device. For now, that works well enough for me, but I would like to see that functionality added in the future.

    Overall, it’s an ideal solution for people like me who like to have access to all of my media, but have limited available storage on my iPhone. It’s way more affordable to just buy one of these when you need extra space than to upgrade your whole device. I would highly recommend this for any heavy iOS user.

    Fore more details, view the “*16GB Wi-Drive*”:http://www.smalldog.com/product/79678/at_kb and the “*32GB Wi-Drive here.*”:http://www.smalldog.com/product/79679/at_kb

    *For a limited time, you can save up to $60–check them out below!*

  • Essential Apps for Your Mac

    My mind is in Spring Cleaning mode right now (maybe because this weather is ridiculously unseasonable?). In between scrubbing the wet paw prints from my entryway due to an early onset of the dreaded Mud Season, I figured I’d do an audit of all of the apps on my Mac to find the ones I’d classify as truly “essential.”

    The following excerpt, originally featured in “*Kibbles & Bytes issue #623,*”:http://blog.smalldog.com/kibbles/kb623/ was a perfect starting point for multiple reasons: the apps mentioned are free, it includes two of my favorite “de-clutter” apps and finally, because it’s fitting that it was written by Ed since we’re watching Spy (and her mud tracks) while he’s out of town.

    *****

    “*OnyX*”:http://www.titanium.free.fr/ is a multifunction maintenance, optimization, and personalization utility for Mac OS X. I use it about once a month or so to keep all my Macs running smoothly.

    OnyX allows you to verify your Mac’s Startup Disk and the structure of its System files, run miscellaneous tasks of system maintenance, configure some hidden parameters of the Finder, Dock, Safari and some of Apple’s own applications, delete caches, remove cumbersome files and folders and more.

    “*VLC*”:http://www.videolan.org/ media player is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, more) as well as DVDs, VCDs, and various streaming protocols.

    In other words, VLC will play back many file formats that the QuickTime Player, Windows Media Player, etc. can’t handle. Best of all, VLC doesn’t need any external codecs or programs to work.

    “*Bean*”:http://www.bean-osx.com/Bean.html is a small, easy-to-use word processor (or more precisely, a rich text editor), designed to make writing convenient and efficient. Bean is Open Source, fully Cocoa, and is available free of charge!

    Bean includes many writing essentials including a live word count, a Get Info panel for in-depth statistics, a zoom-slider to easily change the view scale,
    an Inspector panel with lots of sliders, date-stamped backups, auto-saving, page layout mode and more.

    I combine Bean with “*Think*”:http://www.freeverse.com/apps/app/?id=7013 for efficient, clutter-free writing.

    “*NetNewsWire*”:http://netnewswireapp.com/ is an easy-to-use RSS and Atom reader for your Mac. It allows you to browse, subscribe, read, and save hundreds of thousands of website feeds. It is a true desktop Mac application, with integration with Spotlight, Address Book, iCal, iPhoto, Growl, Twitterific and more. Best of all, it effortlessly syncs with NetNewsWire’s web-based RSS reader for free, allowing you to manage all your RSS feeds from any Internet-connected computer (Mac or PC).

    “*Handbrake*”:http://handbrake.fr/ is an open-source, multithreaded video transcoder available for Mac OS X, Linux and Windows. It will convert just about any video file you can play on your Mac into a variety of other, easier to play, more portable video formats. Most people use HandBrake to back up their DVDs, or convert a DVD into a file that can be played back on their iPod, iPhone, Apple TV, PS3, etc. Use it as you will. HandBrake has been updated substantially over the past several years since its initial release

    I admit, since Time Machine debuted, I don’t use this app as much as I used to. However, for simple, successful backups, “*Carbon Copy Cloner*”:http://www.bombich.com/software/index.html can’t be beat. You can also use CCC3 for backing up across network, backup to disk images, and backup of selected files only. CCC 3 features an interface designed to make the cloning and backup procedure very intuitive. In addition to general backup, CCC can also clone one hard drive to another, copying every single block or file to create an exact replica of your source hard drive.

    Forget the other commercial unarchiving apps (like the free version of StuffIt)–the “*Unarchiver*”:http://wakaba.c3.cx/s/apps/unarchiver.html is all you need. Uncompress RAR, 7zip, tar, and bz2 files on your Mac. The developer notes the “many new Mac users will be puzzled the first time they download a RAR file. Do them a favor and download UnRarX for them!”

    “*Google SketchUp*”:http://sketchup.google.com/ is used to create, modify and share 3D models of anything you like. I know a few people who used SketchUp extensively to plan and pre-visualize house renovations. I’ve used it to create a virtual set for planning camera placement. There are dozens of video tutorials, an extensive Help Center and a worldwide user community for SketchUp, making it relatively easy to learn.

    Want to remove some of the apps you’ve downloaded here, or downloaded in the past? Try “*AppCleaner.*”:http://www.freemacsoft.net/ It’s a small application which allows you to thoroughly uninstall unwanted apps. Installing an application distributes many files throughout your System, using space of your Hard Drive unnecessarily. AppCleaner finds all these small files and safely deletes them.

    *****

    Want more? If you’re looking to add or replace some of what you’re using now, “*check out this list of Top 100 Essential Apps.*”:http://www.mactricksandtips.com/2008/01/top-100-essential-mac-applications.html

  • Weekly Apple News Recap | 2/13-2/17

    Apple had some notable news this week (but no, the iPad 3 isn’t out yet):

    *Apple Releases Mountain Lion Developer Preview*
    Apple announced the ninth major release of OS X, 10.8, this week, and made a preview available to registered developers immediately. A public release is scheduled for late 2012. Taking a cue from iOS once again, Mountain Lion will add Notification Center, Messages, Notes, Reminders and Game Center to the Mac, among other features.

    “*Read more on this story here.*”:http://macdailynews.com/2012/02/16/apple-releases-os-x-mountain-lion-developer-preview/
    “*Read about the preview Tim Cook gave to the Wall Street Journal.*”:http://online.wsj.com/article/SB10001424052970204880404577226864202052768.html
    “*Get a sneak peak here.*”:http://www.apple.com/macosx/mountain-lion/

    *Software Update Goes To the App Store*
    With the release of Mountain Lion, Software Update is relocating (movin’ on up?) to the App Store, thus streamlining users’ app update experience.

    “*Read more here.*”:http://www.pocket-lint.com/news/44410/apple-software-updates-move-to-mac-app-store