How does wireless routing work?

Discussion in 'Wireless Networking' started by nomail1983@hotmail.com, Jan 15, 2006.

  1. Guest

    I do not understand how packets from remote systems reach my PC
    through a wireless router.

    On the local network side of the router, my PC is assigned an IP
    address in the range 192.168.*.*. Of course, that is a private network
    address range. Packets transmitted to an external network cannot
    have 192.168.*.* in the source IP address field, and inbound packets
    from an external network should not have 192.168.*.* in the destination
    IP address field; they should be blocked eventually by some router, or
    by our wireless router as a last resort.

    But Ethereal shows that outbound packets from my PC do have
    192.168.*.* in the source IP field, and inbound packets from external
    systems do have 192.168.*.* in the destination IP field.

    The external network side of the router has an IP address assigned
    dynamically by the cable ISP -- for example, 24.7.*.* assigned by
    Comcast. Websites such as www.showmyip.com confirm that packets
    from my PC have that address in the source IP field.

    So packets leave my PC with source IP address 192.168.*.*, the
    wireless router presumably replaces the source IP field with its own
    24.7.*.* IP address, and the remote system sends packets back to
    24.7.*.*. Both the Comcast cable network and external systems are
    oblivious to the existence of the wireless home network.

    My question is: then, how does the wireless router know that such
    inbound packets should go to my PC instead of another PC on the
    same wireless network? What information does the wireless router
    have and use to demultiplex inbound traffic -- be it part of an
    established TCP session or a TCP SYN, UDP or ICMP packet?
     
    , Jan 15, 2006
    #1
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  2. Guest

    I wrote:
    > My question is: then, how does the wireless router know that such
    > inbound packets should go to my PC instead of another PC on the
    > same wireless network? What information does the wireless router
    > have and use to demultiplex inbound traffic -- be it part of an
    > established TCP session or a TCP SYN, UDP or ICMP packet?


    I forgot to mention ....

    If you can point to any online explanation this as well, I would
    appreciate it. My google searches have not turned up anything.

    Also, if it matters, my wireless router is a Linksys WRT54G. But I
    am hoping for a more general response based on network architecture.

    TIA.
     
    , Jan 15, 2006
    #2
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  3. Guest

    I wrote:
    > My question is: then, how does the wireless router know that such
    > inbound packets should go to my PC instead of another PC on the
    > same wireless network?


    Got my answer: NAT.
     
    , Jan 15, 2006
    #3
  4. Was your answer: public & private keys?

    ~ tc

    "" wrote:

    > I wrote:
    > > My question is: then, how does the wireless router know that such
    > > inbound packets should go to my PC instead of another PC on the
    > > same wireless network?

    >
    > Got my answer: NAT.
    >
    >
     
    =?Utf-8?B?fiB0Yw==?=, Jan 16, 2006
    #4
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