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  1. system says:

    May you pls explain same scenario adding 2 switches and 2 routers in between.

    Computer A -------Switch1-----ROUTER1------------------ROUTER 2 ---- Switch2 ----- Computer B.

    Much Thanks !!

  2. When we see in ARP request packet in the Target hardware address (THA) field 0000.0000.0000 (instead of FFFF.FFFF.FFFF) maybe it is connected with the older broadcast address standard? I have read in the „TCP/IP Illustrated„ written by Kevin R. Fall and W. Richard Stevens in the “Proxy ARP” chapter that „some used an older broadcast address (a host ID of all 0 bits, instead of the current standard of a host ID with all 1 bits)”. I can’t find more information about this older broadcast address standard. Is my conjecture correct?

    Link to the quoted sentence:

  3. Rene,
    Have a small question about the need for ARP or in otherwords, MAC address.

    When the packet has already reached the target network, can't the packet be sent to the recipient based on the unique host id(in that network) alone (the last 8 ip address bits in the case of a /24 network, for example) ? What is need for the concept of MAC address and hence ARP protocol ?


  4. Hi Abc,

    Something to keep in mind is that IP is just the "envelope", IP doesn't describe anything at all about how to actually send an electric signal on the wire or anything like that. We need other protocols like that...on our LAN, we use Ethernet for this:

    Ethernet describes what wires to use, how to send electrical signals etc. Also keep in mind that it doesn't just carry IP traffic...it could be IPv6 or any other protocols, before IP, that could have been IPX for example.

    Besides Ethernet, there's also other protocols.....on our WAN, you might use DSL for example. We use these networks to transport IP but we also don't use Ethernet (nor MAC addresses) there.


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