Possible routing problem because of subnet change.

Discussion in 'Windows Server' started by Steve, Mar 7, 2007.

  1. Steve

    Steve Guest

    We had to change our subnet from 255.255.255.0 to 255.255.0.0 because we were
    running out of room. I'm new to the network side of things. Since we moved,
    we're having problems with things losing connections. Some laser printers
    won't connect when we configure them with an address outside the old range.
    Our label printers lose the connection and we have to reset the print server
    on them. We're a small company, less than 80 computers.

    Do I need a router now that I expanded the subnet?

    Thanks,
     
    Steve, Mar 7, 2007
    #1
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  2. Steve

    Herb Martin Guest

    That is a subnet MASK not a subnet. And please expect us to help
    you by correcting both your terminology and technical mistakes so
    that you can learn how all this works.

    We WANT to help....
    So you had more than about 250 machines on a single subnet, or broadcast
    domain? (generally a single simple hub or same VLAN of a true switch).
    [Being new to networking may make it difficult to answer the questions we
    will
    need to ask -- but hang in there and we will help.]

    What sort of connectivity devices do you have? Do you manage these (now)
    or does someone else do this?

    You might have simple hubs (multiport repeaters which are frequently called
    "100/10 Mbsp switches" even though they are not true switches), or bridges
    (not very likely), or some sort of advanced (true) switch.

    If you have the switch it gets even more complicated (or at least detailed)
    since
    a switch can be either a Bridge (layer 2) that passes broadcasts, or a
    Router
    (layer 3) that does NOT pass broadcasts, or some hybrid combination of
    these two even a VLAN type switch.
    Losing a connection implies that it works SOME of the time and so is
    unlikely
    to be a true routing or hardware problem unless the hardware is only
    intermittantly bad.
    No, but I am answering the question you are asking -- rather than what you
    might better need to know.

    Your choices were to expand the network range (as you did) by reducing
    the length of the subnet mask, OR adding a new subnet.

    IF you were to add a new subnet then you would typically have to employ
    a router to connect the two (or more) subnets together.
     
    Herb Martin, Mar 7, 2007
    #2
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  3. Steve

    Steve Guest

    I'm sorry, I told you that I was new.

    Could my DNS Servers be setup wrong? We have two servers that are configured
    as DNS Servers.
    One of our users keeps having this problem with his laptop. I had him run
    ipconfig and tell me his IP address, but I can't ping it. He is able to get
    to everything (for now). I looked in the DHCP Leases and it lists 2 different
    addresses for him that don't match the one he gave me. The second one is for
    his wireless card. If I try and ping him by host name, it tries checking for
    it at a 4th address.


     
    Steve, Mar 7, 2007
    #3
  4. Steve

    Herb Martin Guest

    Could be as a lot of people, with more experience than you claim, do it
    wrong.
    Do you have ZONES (like your domain names) defined on them? One as
    Primary and the other as Secondary, or perhaps one or both of them as
    Active Directory Integrated if they are DCs?
    He might simple be running the XP firewall with the ICMP protocol (used by
    ping) blocked.

    Does the ping fail by both IP and Name (ip, routing, hardware problem) or
    only by name (dns Problem).

    Is his machine on the same subnet/wire with you? If not, try Tracert and
    see
    how far/close you can get to him....

    Also post the unedited text from "IPConfig /all" from both a working machine
    and his trouble machine....
    So this tends to imply that only access TO him is giving trouble and that
    points
    towards the Firewall idea somewhat.
    So you ping by IP (that he gave you) and see if that works.
    If his wireless card is on "another network" with no routing setup
    (correctly)
    then you won't reach him by that path.
     
    Herb Martin, Mar 7, 2007
    #4
  5. Thanks Herb for his kindly detailed answer!

    Mike Luo

    Microsoft Online Partner Support
    Get Secure! - www.microsoft.com/security

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    Mike Luo [MSFT], Mar 8, 2007
    #5
  6. Steve

    Steve Guest

    Sorry, I got tied up yesterday with WSUS.

    Both of the DNS Servers are DC. Should I only use one DNS Server?

    It fails both ways. His windows firewall is turned off.
     
    Steve, Mar 9, 2007
    #6
  7. Steve

    Herb Martin Guest

    No, generally it is better to have both DCs be DNS servers -- if one
    DC goes down the clients need both the DC and the DNS to still be
    running on the other server.
    So if connection (ping) fails by IP address you do NOT have (primarily)
    a DNS problem -- since this eliminates DNS from the query.

    There might be either an Intermediate Firewall (only in a complex network
    or when going out to the Internet etc) but you say the local firewalls are
    disabled -- this must include any third party stuff like ZoneAlarm or
    Norton System Utilities etc.

    Are these on the "same wire" (e.g., same simple hub)? If not try a tracert
    by IP address and post the results.

    Show the UNEDITED Text from "IPConfig /all >compName.txt" from both
    machines please.


     
    Herb Martin, Mar 9, 2007
    #7
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