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Thread: Packet Question

  1. #1

    Packet Question

    What is a Packet? I know it is a dumb question but i am not familiar with tcp/ip can i just get a breif over view or a link to some good texts. Thank you

  2. #2
    Senior Member
    Join Date
    Jan 2003
    At first I thought this was a joke, then I was tempted to flame.. but since everyone has been lecturing me on being nice... here we go.

    Source: Webopedia

    A piece of a message transmitted over a packet-switching network. See under packet switching. One of the key features of a packet is that it contains the destination address in addition to the data. In IP networks, packets are often called datagrams.
    Source: McGraw-Hill Illustrated Telecom Dictionary

    A unit of data at the network layer of the OSI (Open Systems Interconnect) model. Packets have a header that contains control information and a payload with user data. The terms, datagram, frame, packet data unit, message, and segment aer also used to describe logical information groupings at various layers of the OSI reference model and in various arms of the networking industry.
    Basically it's the way data is grouped to be sent over the Internet (in very very laymans terms). You can get a fairly decent description of the OSI model from routergod.com. Routergod.com does some very very cool explanations of things. Encapsulation takes place at the various levels of the OSI layer, packets at the network layer is just one example, more research will explain the rest to you.

    Encapsulation goes - Data, Segment, Packet, Frame, Bit. You could, to grasp a simple understanding of this, compare it to a letter. You have your thoughts that you wish to convey to the other person (this is the Data). You write them down on the paper, in sequence and checking for errors, to create the letter (you now have your segment). Then you stuff the letter into an envelope (this is your packet). You write your address and the address of your recipient on this envelope much like a computer does when it adds the IP headers to the packet. Now are you going to drop the envelope in a mailbox, or will you send it send it by Courier, or maybe even FedEx or UPS, this is much like the data-link layer and it's frames. Suppose you chose to send it by mail. You drop it in a mailbox. The person who collects it doesn't know where it's going, they simply return it to be sorted. Here your Zip Code/Postal Code (MAC Address) is compared to a database (MAC Address Table/ARP Table) to see where exactly your letter is to be sent (routed). The letter is then sent to that destination (bits @ the physical layer, traveling through some medium). I realize this was probably a stretch, and the more experienced members are laughing right now but hopefully it'll give you a basic idea of how the technology works.

    Now go search and find out more information for yourself. I've given you a few keywords to type into google(I suggest packet +OSI or something along those lines). Good luck with your search.


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