Mix hosts and routers on a subnet?

Discussion in 'Cisco' started by James Harris, Mar 29, 2006.

  1. James Harris

    James Harris Guest

    Hi

    I've always avoided having routers exchange routing updates on a subnet
    that carries hosts. For one thing it avoids the ICMP redirect issues.
    These, however, can be turned off at the router. While it still feels
    wrong I can't think of a simple billy-basic technical reason to avoid
    the sharing of a subnet. There must be one....?

    Can anyone advise either to mix them (hosts and routers) or a good
    reason not to do so?

    --
    TIA,
    James
     
    James Harris, Mar 29, 2006
    #1
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  2. James Harris

    Guest

    There shouldn't be any issues with hosts and multiple routers sharing a
    subnet. Note that when you want redundant routers (as with
    HSRP/VRRP/GLBP) you will certainly have more than one router sharing a
    subnet with hosts.

    Cisco da Gama
    http://ciscostudy.blogspot.com
     
    , Mar 30, 2006
    #2
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  3. James Harris

    Merv Guest

    If the primary role of a network segment was to exchange traffic
    between core routers, one would probably not want to start onnecting
    hosts to that segment.

    On an access segment that has high-availability requirements then one
    would probably find at least two routers running HSRP or equivalaent.
    Exchanging routes over this type of segment/subnet can be done but
    probably is indicative of a design flaw in the access to distribution
    layer.
     
    Merv, Mar 30, 2006
    #3
  4. James Harris wrote:

    > Hi
    >
    > I've always avoided having routers exchange routing updates on a subnet
    > that carries hosts. For one thing it avoids the ICMP redirect issues.
    > These, however, can be turned off at the router. While it still feels
    > wrong I can't think of a simple billy-basic technical reason to avoid
    > the sharing of a subnet. There must be one....?
    >
    > Can anyone advise either to mix them (hosts and routers) or a good
    > reason not to do so?
    >
    > --
    > TIA,
    > James
    >
    >

    Years ago I would have told you that it was a bad idea. Back then a
    design objective was to keep routing segments (as opposed to host
    segments) as pure as possible because you had many protocols (not just
    IP) like IPX that were very "chatty" and LAN bandwidth was at a premium
    because of the collisions issue.


    Today? All that is gone now. Everything is pretty much IP over switched
    ethernet (sometimes GigE to the desktop). With that, the -only- reason
    left to not add PCs to critical routing segments is that some users like
    to play with their Network configurations and unwittingly turn their PCs
    into routers ... it causes some pretty fun issues!... I would preffer
    for that reason alone to keep them away from what I would call a
    "backbone" segment.

    Cheers

    DD
     
    Dick Dastardly, Apr 2, 2006
    #4
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