OSI Model question

bencmcbbencmcb Users Awaiting Email Confirmation Posts: 43 ■■□□□□□□□□
in CCNA & CCENT
I am trying to visualize the OSI model but am having some confusion.

I don't understand this because first of all, if we are going to follow the OSI hierarchy (but starting from the Network layer and sending data outside of the LAN) I see the packets traveling in this order:

Transmitting- Router (Network layer) > Switch (Data Link layer) > Cables (Physical layer)

Receiving- Cables (Physical Layer) > Switch (Data Link layer) > Router (Network Layer) > Host (Tansport layer, Session Layer, Presentation Layer, Application Layer).

Shouldn't the data travel in this way:

Transmitting- Router (Network) > Cables (Physical)

Receiving- Cables (Physical) > Router (Network) > Switch (Data Link) > Host (Tansport layer, Session Layer, Presentation Layer, Application Layer).
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Comments

  • wastedtimewastedtime Member Posts: 586 ■■■■□□□□□□
    Not really sure what you are getting at in that post but maybe this picture will help.

    sn770202.jpg
    The lines at the bottom are the path that the data would be taking through the network.
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  • IRONMONKUSIRONMONKUS Member Posts: 143 ■■■□□□□□□□
    I like that diagram, thank you. I never thought about the different layers that might take place within the switches and routers.
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  • Technology1Technology1 Member Posts: 50 ■■□□□□□□□□
    Here's another one.

    osi_model.jpg
    IRONMONKUS wrote: »
    I like that diagram, thank you. I never thought about the different layers that might take place within the switches and routers.
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  • Greenmet29Greenmet29 Member Posts: 240
    Wastedtime...That picture is pure genius. I understood the way that data passes through the network already, but this diagram reinforced what I already thought I knew! Thanks!icon_thumright.gif
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  • bencmcbbencmcb Users Awaiting Email Confirmation Posts: 43 ■■□□□□□□□□
    This was very helpful. Thank you.

    Is the Network layer not being used when data is traveling within a LAN?
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  • Greenmet29Greenmet29 Member Posts: 240
    It is, but not at the switch. When the receiving node gets it, it check the destination network layer address (IP Address) and if the packet belongs to that node, it strips the network layer header off and passes it to the transport layer. If it doesn't (could be a broadcast or unknown unicast), it discards the packet.
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  • hermeszdatahermeszdata Member Posts: 225
    Greenmet29 wrote: »
    It is, but not at the switch. When the receiving node gets it, it check the destination network layer address (IP Address) and if the packet belongs to that node, it strips the network layer header off and passes it to the transport layer. If it doesn't (could be a broadcast or unknown unicast), it discards the packet.

    This will make more sense once you understand LAN switching and how switch functionallity!
    John
    Current Progress:
    Studying:
    CCNA Security - 60%, CCNA Wireless - 80%, ROUTE - 10% (Way behind due to major Wireless Project)
    Exams Passed:
    CCNA - 640-802 - 17 Jan 2011 -- CVOICE v6 - 642-436 - 28 Feb 2011
    2011 Goals
    CCNP/CCNP:Voice
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