Loop back address - Networking

This is a discussion on Loop back address - Networking ; Hi all, The following is the definition of loop back address ,i saw in the book tcp/ip guide special range of addresses ,127.0.0.0 to 127.255.255.255 , is set aside for loop back functionality.IP datagrams sent by a host to a ...

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Thread: Loop back address

  1. Loop back address

    Hi all,

    The following is the definition of loop back address ,i saw in the
    book tcp/ip guide

    special range of addresses ,127.0.0.0 to 127.255.255.255 , is set
    aside for loop back functionality.IP datagrams sent by a host to a
    127.x.x.x loop back address are not passed down to the data link layer
    for transmission,instead they loopback
    to the source device at the IP level. In essence this short circuits
    the normal protocol stack; data is sent by a device's layer 3 IP
    implementation and immediately received by it.

    This loopback range is used for testing the TCP/IP protocol
    implementation on a host. since the lower layers are short
    circuited ,sending to a loopback address allows you to isolate and
    test the higher layers ,IP and above without interference from lower
    layers. 127.0.0.1 is the address most commonly used for testing
    purposes

    now my question is as follows

    1)This loopback range is used for testing the TCP/IP protocol
    implementation on a host. since the lower layers are short
    circuited ,sending to a loopback address allows you to isolate and
    test the higher layers

    can any one give example(s) for this or a situation where this is
    used ?


  2. Re: Loop back address

    Hi.

    I'm using the loopback-IF to for e.q. to check, if my deamons (apache,
    snmpd, ...) are locally running and if the right ports are in listenning
    state (well, this can show netstat too ...).

    regards


    schrieb im Newsbeitrag
    news:c1b928ea-2be6-41fd-817e-c39bcf4d57b2@r15g2000prh.googlegroups.com...
    > Hi all,
    >
    > The following is the definition of loop back address ,i saw in the
    > book tcp/ip guide
    >
    > special range of addresses ,127.0.0.0 to 127.255.255.255 , is set
    > aside for loop back functionality.IP datagrams sent by a host to a
    > 127.x.x.x loop back address are not passed down to the data link layer
    > for transmission,instead they loopback
    > to the source device at the IP level. In essence this short circuits
    > the normal protocol stack; data is sent by a device's layer 3 IP
    > implementation and immediately received by it.
    >
    > This loopback range is used for testing the TCP/IP protocol
    > implementation on a host. since the lower layers are short
    > circuited ,sending to a loopback address allows you to isolate and
    > test the higher layers ,IP and above without interference from lower
    > layers. 127.0.0.1 is the address most commonly used for testing
    > purposes
    >
    > now my question is as follows
    >
    > 1)This loopback range is used for testing the TCP/IP protocol
    > implementation on a host. since the lower layers are short
    > circuited ,sending to a loopback address allows you to isolate and
    > test the higher layers
    >
    > can any one give example(s) for this or a situation where this is
    > used ?
    >




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