ping one address and get another

Discussion in 'Computer Support' started by Obelisk, Jun 21, 2007.

  1. Obelisk

    Obelisk Guest

    Got a hired network printer with an IP of 192.168.1.11.
    When I ping 192.168.1.255 I get a reply from the printer.

    The printer gets the address from a server and shows the 192.168.1.11
    on the config screen. Ping either address and get the same response

    Quite baffled. Never seen this before in over 10 years of looking
    after this system




    --
    Posted via a free Usenet account from http://www.teranews.com
     
    Obelisk, Jun 21, 2007
    #1
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  2. Obelisk

    Keme Guest

    Obelisk skrev:
    > Got a hired network printer with an IP of 192.168.1.11.
    > When I ping 192.168.1.255 I get a reply from the printer.
    >
    > The printer gets the address from a server and shows the 192.168.1.11
    > on the config screen. Ping either address and get the same response
    >
    > Quite baffled. Never seen this before in over 10 years of looking
    > after this system
    >
    >
    >
    >


    If you have 24 bits netmask (255.255.255.0) and use the defaults for
    addressing, the ...255 address is the broadcast address for your subnet.
    That means any packet addressed to 192.168.1.255 is addressed to every
    node on that network, so you should get response from any node
    configured to reply to ping, I guess.
     
    Keme, Jun 21, 2007
    #2
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  3. Obelisk

    Desk Rabbit Guest

    Obelisk wrote:
    > Got a hired network printer with an IP of 192.168.1.11.
    > When I ping 192.168.1.255 I get a reply from the printer.
    >
    > The printer gets the address from a server and shows the 192.168.1.11
    > on the config screen. Ping either address and get the same response
    >
    > Quite baffled. Never seen this before in over 10 years of looking
    > after this system
    >

    When you ping a broadcast address, some devices but not all will reply.

    http://www.freesoft.org/CIE/RFC/1122/46.htm

    "An ICMP Echo Request destined to an IP broadcast or IP multicast
    address MAY be silently discarded."
     
    Desk Rabbit, Jun 21, 2007
    #3
  4. Obelisk

    Rick Merrill Guest

    Obelisk wrote:
    > Got a hired network printer with an IP of 192.168.1.11.
    > When I ping 192.168.1.255 I get a reply from the printer.
    >
    > The printer gets the address from a server and shows the 192.168.1.11
    > on the config screen. Ping either address and get the same response
    >
    > Quite baffled. Never seen this before in over 10 years of looking
    > after this system
    >
    >
    >
    >


    Did you assign the IP to the printer or did it use DHCP to get one?
     
    Rick Merrill, Jun 21, 2007
    #4
  5. Obelisk

    Obelisk Guest

    On Thu, 21 Jun 2007 14:56:36 +0200, Keme <>
    wrote:

    >Obelisk skrev:
    >> Got a hired network printer with an IP of 192.168.1.11.
    >> When I ping 192.168.1.255 I get a reply from the printer.
    >>
    >> The printer gets the address from a server and shows the 192.168.1.11
    >> on the config screen. Ping either address and get the same response
    >>
    >> Quite baffled. Never seen this before in over 10 years of looking
    >> after this system
    >>
    >>
    >>
    >>

    >
    >If you have 24 bits netmask (255.255.255.0) and use the defaults for
    >addressing, the ...255 address is the broadcast address for your subnet.
    >That means any packet addressed to 192.168.1.255 is addressed to every
    >node on that network, so you should get response from any node
    >configured to reply to ping, I guess.


    But there are another 45 addresses on the network and the only one the
    255 ping returns is the 11.

    OTOH that address is the only one allocated by the server. All the
    rest are static. Something to check on when I get back in next week.
     
    Obelisk, Jun 21, 2007
    #5
  6. Obelisk

    why? Guest

    On Thu, 21 Jun 2007 11:30:21 +0100, Obelisk wrote:

    >
    >Got a hired network printer with an IP of 192.168.1.11.
    >When I ping 192.168.1.255 I get a reply from the printer.


    Oh dear the broadcast address reply issue. You can't rely on the
    response from the 1.255 address. Some devices will others won't

    >The printer gets the address from a server and shows the 192.168.1.11
    >on the config screen. Ping either address and get the same response


    You didn't say what the response was, a valid reply or fail.

    Then check the MAC address on the printer and the output of ARP (a list
    of IPs/MAC) against the IP address.

    >Quite baffled. Never seen this before in over 10 years of looking
    >after this system


    Lucky you.

    Me
     
    why?, Jun 21, 2007
    #6
  7. Obelisk

    Obelisk Guest

    On Thu, 21 Jun 2007 09:56:02 -0400, Rick Merrill
    <> wrote:

    >Obelisk wrote:
    >> Got a hired network printer with an IP of 192.168.1.11.
    >> When I ping 192.168.1.255 I get a reply from the printer.
    >>
    >> The printer gets the address from a server and shows the 192.168.1.11
    >> on the config screen. Ping either address and get the same response
    >>
    >> Quite baffled. Never seen this before in over 10 years of looking
    >> after this system
    >>
    >>
    >>
    >>

    >
    >Did you assign the IP to the printer or did it use DHCP to get one?


    dhcp. The installer tried to assigning the one we used on the old
    machine but for some reason it wouldn't take. Tried letting it pick up
    one from a reserved list on the server and it worked. We keep a set
    of static addresses for printers, bridges etc. No problems with any of
    the others or with the old printer. This is actually a photocopier
    that does network printing, scanning, fax. May make coffee too but I
    don't have a manual. It all works but this pinging has me puzzled.
     
    Obelisk, Jun 21, 2007
    #7
  8. Obelisk

    Obelisk Guest

    On Thu, 21 Jun 2007 15:47:17 GMT, why?
    <fgrirp*sgc@VAINY!Qznq.fpvragvfg.pbz> wrote:

    >
    >On Thu, 21 Jun 2007 11:30:21 +0100, Obelisk wrote:
    >
    >>
    >>Got a hired network printer with an IP of 192.168.1.11.
    >>When I ping 192.168.1.255 I get a reply from the printer.

    >
    >Oh dear the broadcast address reply issue. You can't rely on the
    >response from the 1.255 address. Some devices will others won't
    >
    >>The printer gets the address from a server and shows the 192.168.1.11
    >>on the config screen. Ping either address and get the same response

    >
    >You didn't say what the response was, a valid reply or fail.


    It replies with the address of the printer in both cases.
    A fail would not return any address
    >
    >Then check the MAC address on the printer and the output of ARP (a list
    >of IPs/MAC) against the IP address.
    >
    >>Quite baffled. Never seen this before in over 10 years of looking
    >>after this system

    >
    >Lucky you.


    Indeed.
    But still curious as to what is going on
     
    Obelisk, Jun 21, 2007
    #8
  9. Obelisk

    why? Guest

    On Thu, 21 Jun 2007 19:18:51 +0100, Obelisk wrote:

    >On Thu, 21 Jun 2007 15:47:17 GMT, why?
    ><fgrirp*sgc@VAINY!Qznq.fpvragvfg.pbz> wrote:
    >
    >>
    >>On Thu, 21 Jun 2007 11:30:21 +0100, Obelisk wrote:
    >>
    >>>
    >>>Got a hired network printer with an IP of 192.168.1.11.
    >>>When I ping 192.168.1.255 I get a reply from the printer.

    >>
    >>Oh dear the broadcast address reply issue. You can't rely on the
    >>response from the 1.255 address. Some devices will others won't
    >>
    >>>The printer gets the address from a server and shows the 192.168.1.11


    DHCP then. We always use static addresses for printer.

    With DHCP from the server, view the lease details and see if the MAC
    address matches the printer.

    >>>on the config screen. Ping either address and get the same response

    >>
    >>You didn't say what the response was, a valid reply or fail.

    >
    >It replies with the address of the printer in both cases.
    >A fail would not return any address


    Really?

    So you mean a ping if the IP is doing

    Pinging 192.168.0.1 with 32 bytes of data:
    Reply from 192.168.0.1: bytes=32 time=1ms TTL=254

    As long as you stick to using the IP address, it doesn't matter if there
    is any name lookup as it's possible to get the wrong IP/name and still
    get a good ping.

    >>
    >>Then check the MAC address on the printer and the output of ARP (a list
    >>of IPs/MAC) against the IP address.


    So does the IP address from displaying the arp table on a PC give a MAC
    address that is the same as the MAC address from the printer?

    >>
    >>>Quite baffled. Never seen this before in over 10 years of looking
    >>>after this system

    >>
    >>Lucky you.

    >
    >Indeed.
    >But still curious as to what is going on


    Then you need a packet sniffer on the PC you run the ping from, to see
    exactly what happens.

    Check the arp question from earlier.

    Until you can match the IP address with the physical MAC address you
    can't be sure which device is replying.

    Turn the printer off and do the ping again.

    PING to Broadcast Address May Get Response
    If the PING command is used to a broadcast address, some devices will
    respond. The following RFC section discusses pinging a broadcast
    address: ...
    http://support.microsoft.com/support/kb/articles/Q137/4/21.asp - Similar
    pages

    Me
     
    why?, Jun 21, 2007
    #9
  10. Obelisk wrote:
    > On Thu, 21 Jun 2007 15:47:17 GMT, why?
    > <fgrirp*sgc@VAINY!Qznq.fpvragvfg.pbz> wrote:
    >
    >
    >>On Thu, 21 Jun 2007 11:30:21 +0100, Obelisk wrote:
    >>
    >>
    >>>Got a hired network printer with an IP of 192.168.1.11.
    >>>When I ping 192.168.1.255 I get a reply from the printer.

    >>
    >>Oh dear the broadcast address reply issue. You can't rely on the
    >>response from the 1.255 address. Some devices will others won't
    >>
    >>
    >>>The printer gets the address from a server and shows the 192.168.1.11
    >>>on the config screen. Ping either address and get the same response

    >>
    >>You didn't say what the response was, a valid reply or fail.

    >
    >
    > It replies with the address of the printer in both cases.
    > A fail would not return any address
    >
    >>Then check the MAC address on the printer and the output of ARP (a list
    >>of IPs/MAC) against the IP address.
    >>
    >>
    >>>Quite baffled. Never seen this before in over 10 years of looking
    >>>after this system

    >>
    >>Lucky you.

    >
    >
    > Indeed.
    > But still curious as to what is going on


    They've explained it. When you send to the 255 address it doesn't just
    go that one address, it goes them all. Only your printer is set up to
    respond to it. Not a mystery.
    http://www.linuxjunkies.org/network/tcpip/intro7.html
     
    =?ISO-8859-1?Q?R=F4g=EAr?=, Jun 21, 2007
    #10
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