DHCP across routers

Discussion in 'Cisco' started by lelo, Nov 28, 2005.

  1. lelo

    lelo Guest

    We have a network at headquarters that resides on a 10.16.248.0 subnet.
    That network is connected via frame relay to 7 remote sites on a
    10.17.1.0, 10.17.2.0, 10.17.3.0, up to 10.17.7.0 subnet. To keep the
    subnets uniform at the remote sites and at HQ we want to change the
    remote site subnets to 10.16.1.0, 10.16.2.0, 10.16.3.0, up to
    10.16.7.0. Each subnet at each location gets it's ip address from a
    dhcp server at that particular site. My question is can dhcp request
    and ip address allocations cross router from remote site to
    headquarters or vice versa? We want our address allocation to remain
    the same (site specific dhcp)
    lelo, Nov 28, 2005
    #1
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  2. lelo

    Phil Schuman Guest

    "lelo" <> wrote in message
    news:...
    > We have a network at headquarters that resides on a 10.16.248.0

    subnet.
    > That network is connected via frame relay to 7 remote sites on a
    > 10.17.1.0, 10.17.2.0, 10.17.3.0, up to 10.17.7.0 subnet. To keep the
    > subnets uniform at the remote sites and at HQ we want to change the
    > remote site subnets to 10.16.1.0, 10.16.2.0, 10.16.3.0, up to
    > 10.16.7.0. Each subnet at each location gets it's ip address from a
    > dhcp server at that particular site. My question is can dhcp request
    > and ip address allocations cross router from remote site to
    > headquarters or vice versa? We want our address allocation to remain
    > the same (site specific dhcp)
    >

    normally DHCP requests are blocked at the router - since they are
    "broadcasts",
    however, you can add a "helper relay" definition for each router
    and specify where to "forward" the DHCP requests...
    We had the same setup - for our 50 remote sites -
    and served they all from a central location - actually 2 locations -
    Phil Schuman, Nov 28, 2005
    #2
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  3. lelo

    Hansang Bae Guest

    lelo wrote:

    > We have a network at headquarters that resides on a 10.16.248.0
    > subnet. That network is connected via frame relay to 7 remote sites
    > on a 10.17.1.0, 10.17.2.0, 10.17.3.0, up to 10.17.7.0 subnet. To keep
    > the subnets uniform at the remote sites and at HQ we want to change
    > the remote site subnets to 10.16.1.0, 10.16.2.0, 10.16.3.0, up to
    > 10.16.7.0.


    It's in the 10.0.0.0 address space so I'm not sure what the benefit of
    doing this is. Unless you're just using it "as an example only"

    > Each subnet at each location gets it's ip address from a
    > dhcp server at that particular site. My question is can dhcp request
    > and ip address allocations cross router from remote site to
    > headquarters or vice versa? We want our address allocation to remain
    > the same (site specific dhcp)


    You can if you use "ip helper-address IP_OF_DHCP_SERVER" at each
    ethernet interface. But when you do this, it actually opens up a lot
    of unwanted broadcasts packets by default. So you should lock it back
    down.

    See: http://www.cisco.com/warp/public/473/winnt_dg.htm#xtocid88297



    --

    hsb


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    Hansang Bae, Nov 28, 2005
    #3
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