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  • How does internet routing work?

    From [email protected]@21:1/5 to All on Fri May 18 02:06:05 2018
    If I send a packet to <IP address>, how does the router know where to send it to? I saw on a video on the net, where Vint Cerf *himself* said that an IP address has <some bits> reserved for country, then city, and so on.... is that true? ...makes it
    sound kind of like a PHONE no...? :)

    (I've already read a book on networks, but this was not explained....)


    Thanks.

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  • From Jorgen Grahn@21:1/5 to [email protected] on Fri May 18 10:39:59 2018
    On Fri, 2018-05-18, [email protected] wrote:
    If I send a packet to <IP address>, how does the router

    Which router?

    know where to send it to?

    It has a routing table which answers "which of my neighboring nodes
    should I send this packet to, to get it /closer to/ its destination?"

    Home routers tend to have a simple, handmade routing table.
    Routers out on the net learn from each other, using elaborate
    schemes I know little about.

    I saw on a video on the net, where Vint Cerf
    *himself* said that an IP address has <some bits> reserved for
    country, then city, and so on.... is that true?

    No.

    /Jorgen

    --
    // Jorgen Grahn <grahn@ Oo o. . .
    \X/ snipabacken.se> O o .

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  • From Les Cargill@21:1/5 to [email protected] on Fri May 18 21:09:06 2018
    [email protected] wrote:
    If I send a packet to <IP address>, how does the router know where to
    send it to? I saw on a video on the net, where Vint Cerf *himself*
    said that an IP address has <some bits> reserved for country, then
    city, and so on.... is that true? ...makes it sound kind of like a
    PHONE no...? :)

    (I've already read a book on networks, but this was not
    explained....)


    Thanks.



    1) There is the usual, netmask-based routing yuou're likely to see in
    a residence.

    2) There are more sophisticated protocols for rules or
    learning at layer three. One such is OSPF.

    Effectively, what a router needs to understand is "Given this PDU, which
    port to I send it on?". The answer may be "no port at all."

    Technically, a canonical router has only two ports.

    --
    Les Cargill

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