Expanding Subnet

Discussion in 'Server Networking' started by Will Sellers, Aug 31, 2007.

  1. Will Sellers

    Will Sellers Guest

    We are running out of IP address for the standard 255 255 255 0 range.
    If I re subnet my DHCP to 255 255 254 0 will I have to change every device
    that is using a static IP?
    ex servers
    printers
    access points
     
    Will Sellers, Aug 31, 2007
    #1
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  2. hi,
    yes you have to do that.
    for 128.128.0.0 /23 you will have range IP's from 128.128.0.1-128.128.1.254
    so for IP's (128.128.0.1-128.128.0.254)/23 and (128.128.0.1-128.128.0.254)/24
    they will se each other with no problem, the problem will apear on
    (128.128.0.1-128.128.0.254)/24 that's IP's will not see any on the IP's
    (128.128.1.1 -128.128.1.254)/23
     
    Dragos CAMARA, Aug 31, 2007
    #2
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  3. Create a new 254 host network and put a router between them. IP segments
    need to stay below 250-300 hosts for ethernet to remain efficient. This is
    the case for Ethernet even if it wasn't running TCP/IP and was using IPX/SPX
    or something else. Ethernet functions by broadcasting,..the more hosts, the
    more broadcasts,...the more broadcasts the less effiecient. It isn't about
    just PCs,...routers, switches, and other network devices generate a load on
    the wire as well.

    Using masks that are lower bit than /24 (more than 254 hosts) are for
    supernetting over backbones where it is then broken down into smaller IP
    segment at a down stream router.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
     
    Phillip Windell, Aug 31, 2007
    #3
  4. This also means you won't have to reconfigure any of your existing
    equipment. You just add a LAN Router into the system and create the new
    segment off of the router's other interface. The new segment at first would
    have nothing on it at all. You would then move Hosts to the new segment
    over time as needed and according to if there is a logical reason to move
    any old Hosts to the new segment.

    You can't take as much time as you want to finish it from that point.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
     
    Phillip Windell, Aug 31, 2007
    #4
  5. Sorry,..typo,...

    You **can** take as much time as you want to finish it from that point.
     
    Phillip Windell, Aug 31, 2007
    #5
  6. Will Sellers

    Will Sellers Guest

    Hmmmm
    We currently have one dual channel router that combines 2 T1'S INTO ONE BIG
    PIPE.
    This router is our gateway.
    How would I add another router?
     
    Will Sellers, Sep 1, 2007
    #6
  7. it's ok you oppinion , but in that case you "moved" all traffic of
    servers,printers etc of the new clients throught that router wich can be
    worst than the broadcast. Modern switces can limit the broadcast, multicast
    and collisions.
     
    Dragos CAMARA, Sep 1, 2007
    #7
  8. It won't be worse than broadcast damage. Good quality LAN Routers are not
    that slow. It is certainly never going to happen with only 2 subnets with
    254 hosts on each side. But you are also supposed to put the printers and
    servers into the segment with the Hosts that use them the most. Now Layer3
    Switches, which are just switches and routers built into the same case may
    be capable of 256 subnets (VLANs) and if you had 254 hosts on each VLAN that
    would be 65,024 hosts on a single Router. So yes, that could be a problem.
    But most traditional small/meduim business LAN Routers will only have 2 or 4
    Ethernet ports with 2-4 subnets.
    Yes, switches will stop collisions which greatly helps the possible damage
    done by broadcasts and a fully switched LAN would not degrade as quicky as
    a non-switched LAN if there were too many hosts, but they do nothing for
    broadcasts,...unless they are Layer3 Switches,..but then "Layer3" makes them
    Routers. They are LAN Routers and Switches built into the same physical
    box,..but you still have to logically separate the two different roles when
    designing the LAN.

    I guess my larger point of this whole thing is that LANs should be carefully
    planned out for this kind of stuff,..a guy should not just roll back the
    mask a bit or two and keep throwing hosts at it. Proper guidlines and
    pinciples should always be followed even if you don't think you need them at
    the moment,...you'll need them eventually,...it will catch up to you.


    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Sep 4, 2007
    #8
  9. LAN Routers and Internet Routes have nothing to do with each other.

    You'd have to buy a LAN Router (or Layer3 Switch and learn VLANing).

    Your existing LAN is already *one* segment.
    One interface of the LAN router Plugs into your LAN.

    The other interface(s) of the LAN Router plugs into the "new"
    segment,...which in its simplest form is just a matter of plugging a new
    switch into this. Whatever hosts plug into this new switch are on the new
    segment (assuming your properly configured TCP/IP for this new segment).

    The original Segment remains untouched except for changing the Default
    Gateway. Everything has to use the LAN Router as the Default Gateway,...the
    LAN Router itself, in turn, uses the Internet Sharing Device (whatever that
    is) as its Default Gateway.

    <Internet>
    |
    [Internet Router]
    |
    <Public Segment>
    |
    [Internet Sharing Device (Firewall?)]
    |
    <original LAN Segment>
    |
    [LAN Router]
    |
    <new LAN segment>

    If your Internet Router is also the current Default Gateway of the LAN then
    that device is serving multiple purposes within the same hardware box and
    you have *no* public segment. This is not how T1 lines are typically
    done,..this is how home-user broadband technologies are done (DSL &
    CableTV).
    You would have this:

    <Internet>
    |
    [Internet Router & NAT Firewall]
    |
    <original LAN Segment>
    |
    [LAN Router]
    |
    <new LAN segment>

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Sep 4, 2007
    #9
  10. hi,
    i agree with you, but what i wanted to do was to check that isn't enought to
    put a router there, even you put a router or just modify the mask you have to
    solve some problems wich for sure are different for each approach and have to
    balance pro and cons of what you wanna to do, how many workstations, what
    traffic is there, what switches etc.
     
    Dragos CAMARA, Sep 5, 2007
    #10
  11. I agree.

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Sep 5, 2007
    #11
  12. Will Sellers

    Dana Guest

    2 T1's is not a big pipe.
    Same way routers are added to any other network.
     
    Dana, Oct 2, 2007
    #12
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