Re: Why is non-routeable 10.100.10.x routing far beyond my network?

Discussion in 'Cisco' started by Peter, Nov 15, 2004.

  1. Peter

    Peter Guest

    Hi Bob,

    bobcov wrote:
    > Thank you all very much for the explanation. What do you suppose is
    > being done behind that final hop on the traceroute?


    Its not really possible to tell, as that address is completely within
    their control and probably only accessible to them. My local ADSL feed
    has a single hop that uses a 192.168.x.x address. I can see it on
    traceroute, but I can't get to that device from my "real world"
    address at all.


    > Is that where there some large data center for Comcast or something?


    I live in the South Pacific so I know little about Comcast sorry,
    however I imagine they do have many Service points that possibly use
    this addressing. As a Network provider I imagine they could be using
    it all over the country (world?), and not just at one specific location.

    > Seems odd to me that they would allow my traffic into their control
    > equipment, if that's what it is. I think I will change to 172.x.x.x


    There should be no need, as your "private" Network should never come
    into direct contact with any other "private" network, each "private"
    segment should be isolated from the others with a "real-world" address
    between them. In the case of an end user with NAT, the "Public"
    addresses are totally invisible to any device outside the users own
    house, so no issue arises there either.


    >
    > -Bob
    >
    >
    >
    > Peter <> wrote in message news:<FsGld.1306$>...
    >
    >>Hi Bob,
    >>
    >>bobcov wrote:
    >>
    >>>I discovered by accident that I can see a device on 10.100.10.1. I
    >>>ended up on a cable modem config page when I entered that into my web
    >>>browser by mistake instead of 10.0.0.2 (I recently changed addresses
    >>>for my router and forgot I had).

    >>
    >>Just to clarify things, ALL TCP/IP addresses are Routeable. The so
    >>called "Private" address ranges are not usually used on the public
    >>internet as such, however some service providers do use them WITHIN
    >>their part of the public internet, such that normal IP Traffic passes
    >>THROUGH the "private address space" without problem, and while those
    >>addresses may be visible on Traceroutes, you will probably find that
    >>you cannot directly address any of those boxes from real world IP
    >>addresses outside that providers area. This can only work if real
    >>world addresses exist on either side of the "private" addressing and
    >>the environment is managed correctly.
    >>
    >>ISP's often use these address ranges because they can save money (and
    >>real internet address space), because they do not have to use IP
    >>addressing that costs them money. The have to be very careful that
    >>they correctly manage the routing of all traffic THROUGH that address
    >>space though.
    >>
    >>Cheers...........pk.



    --
    *** Replace SOMEONE with prk ***
    Peter, Nov 15, 2004
    #1
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