Wireless Network Design

Discussion in 'Cisco' started by Bob Simon, Aug 8, 2008.

  1. Bob Simon

    Bob Simon Guest

    I set up a wireless router in my upstairs home office (providing good
    coverage for the second floor) and a second one downstairs in the
    living room where signal strength is too low to be useful. There are
    probably lots of different ways to do this but I would like feedback
    on the theoretical as well as practical pros and cons of two
    approaches:

    1) One wired network (192.168.0.0) connecting the LAN port of the DSL
    modem and the WAN ports of both wireless routers. Each router would
    give out their own small pool of DHCP addresses, 192.168.1.0 upstairs
    and 192.168.2.0 downstairs.

    2) The wireless router upstairs would be the only one with DHCP
    enabled and would connect to the one downstairs via the LAN-side
    switch. In effect, this turns the downstairs router into a bridged
    access point.

    Are both approaches equally valid?
     
    Bob Simon, Aug 8, 2008
    #1
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  2. Bob Simon

    Stephen Guest

    On Fri, 08 Aug 2008 08:07:47 -0500, Bob Simon <>
    wrote:

    >I set up a wireless router in my upstairs home office (providing good
    >coverage for the second floor) and a second one downstairs in the
    >living room where signal strength is too low to be useful. There are
    >probably lots of different ways to do this but I would like feedback
    >on the theoretical as well as practical pros and cons of two
    >approaches:
    >
    >1) One wired network (192.168.0.0) connecting the LAN port of the DSL
    >modem and the WAN ports of both wireless routers. Each router would
    >give out their own small pool of DHCP addresses, 192.168.1.0 upstairs
    >and 192.168.2.0 downstairs.


    this one stops you sharing files / printers etc between devices
    attached to the 2 routers.

    It is difficult to connect if your modem only has 1 Ethernet port.

    it also breaks down completely if the provider only allows you a
    single WAN IP address at a time....
    >
    >2) The wireless router upstairs would be the only one with DHCP
    >enabled and would connect to the one downstairs via the LAN-side
    >switch. In effect, this turns the downstairs router into a bridged
    >access point.


    this is more common (mainly because SOHO routers are cheaper than
    dedicated access points).
    You are using the LAN only box as a switch / access point only.
    Some boxes have "AP only" mode this as a setup option.

    >
    >Are both approaches equally valid?


    no - 1st one doesnt work if you only get 1 address.
    --
    Regards

    - replace xyz with ntl
     
    Stephen, Aug 8, 2008
    #2
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  3. Bob Simon

    Bob Simon Guest

    On Fri, 08 Aug 2008 18:20:05 GMT, Stephen <>
    wrote:

    >On Fri, 08 Aug 2008 08:07:47 -0500, Bob Simon <>
    >wrote:
    >
    >>I set up a wireless router in my upstairs home office (providing good
    >>coverage for the second floor) and a second one downstairs in the
    >>living room where signal strength is too low to be useful. There are
    >>probably lots of different ways to do this but I would like feedback
    >>on the theoretical as well as practical pros and cons of two
    >>approaches:
    >>
    >>1) One wired network (192.168.0.0) connecting the LAN port of the DSL
    >>modem and the WAN ports of both wireless routers. Each router would
    >>give out their own small pool of DHCP addresses, 192.168.1.0 upstairs
    >>and 192.168.2.0 downstairs.

    >
    >this one stops you sharing files / printers etc between devices
    >attached to the 2 routers.
    >
    >It is difficult to connect if your modem only has 1 Ethernet port.
    >
    >it also breaks down completely if the provider only allows you a
    >single WAN IP address at a time....
    >>
    >>2) The wireless router upstairs would be the only one with DHCP
    >>enabled and would connect to the one downstairs via the LAN-side
    >>switch. In effect, this turns the downstairs router into a bridged
    >>access point.

    >
    >this is more common (mainly because SOHO routers are cheaper than
    >dedicated access points).
    >You are using the LAN only box as a switch / access point only.
    >Some boxes have "AP only" mode this as a setup option.
    >
    >>
    >>Are both approaches equally valid?

    >
    >no - 1st one doesnt work if you only get 1 address.


    I hooked up my two routers as per the second design and everything
    works except roaming. I set the SSID and WEP keys the same and put
    one router on channel 1 and the other on channel 6. When I go from my
    upstairs office to the living room, the signal strength meter displays
    zero or one bar but XP does not switch to the downstairs AP unless I
    disable or disconnect the wireless connection. When I re-enable or
    re-connect, I get five bars. Can this switchover be made to occur
    automatically?

    Also, I don't understand your comment that my first design won't work
    because
    >it also breaks down completely if the provider only allows you a
    >single WAN IP address at a time....


    My ISP provides a single public static IP address to the WAN port of
    the DSL modem. But since this modem does NAT, it should be able to
    handle mulitple inside hosts with private addresses up to the limit of
    its ability to handle translations without excessive delay. Right?

    --
    Bob Simon
    Please remove Xs from domain for direct replies.
     
    Bob Simon, Aug 9, 2008
    #3
  4. Bob Simon

    Merv Guest


    >
    > My ISP provides a single public static IP address to the WAN port of
    > the DSL modem. But since this modem does NAT, it should be able to
    > handle mulitple inside hosts with private addresses up to the limit of
    > its ability to handle translations without excessive delay. Right?


    Are you able to configure the DSL modem ?

    If for example the DSL modem is setup to only NAT 192.168.0..0/24 then
    you might have an issue ....

    If you can control its configuration so that it will NAT
    192.168.0.0/16, then you should be okay
     
    Merv, Aug 9, 2008
    #4
  5. Bob Simon

    Bob Simon Guest

    On Sat, 9 Aug 2008 14:12:46 -0700 (PDT), Merv <>
    wrote:

    >> My ISP provides a single public static IP address to the WAN port of
    >> the DSL modem. But since this modem does NAT, it should be able to
    >> handle mulitple inside hosts with private addresses up to the limit of
    >> its ability to handle translations without excessive delay. Right?

    >
    >Are you able to configure the DSL modem ?
    >
    >If for example the DSL modem is setup to only NAT 192.168.0..0/24 then
    >you might have an issue ....
    >
    >If you can control its configuration so that it will NAT
    >192.168.0.0/16, then you should be okay


    The modem is a Motorola/Netopia 2210-02. Motorola tech support said
    it's been customized per ATT specs with some functionality stripped
    out. I am able to configure it via the web interface plus via telnet,
    which offers additional configuration granularity. There is no manual
    available but the CLI offers help screens and command options. I only
    see four NAT features:
    mode -- NAT default server mode
    mode (off) [ off | default-server | ip-passthrough ]
    address -- NAT default server IP address
    dhcp-enable -- NAT IP Passthrough DHCP enabled
    host-hardware-address -- NAT IP Passthrough host hardware

    Why would it be useful for the modem to be able to NAT for more than
    one class c subnet? Wouldn't the following scenario work?

    DSL Modem
    WAN: public static
    LAN: 192.168.0.1/24
    Def GW: WAN port
    NAT for 192.168.0.0/24 to public static IP

    Wireless Rtr 1
    WAN: 192.168.0.2/24
    LAN: 192.168.1.1/24
    Def GW: 192.168.0.1
    NAT for 192.168.1.0/24 to 192.168.0.2

    Wireless Rtr 2
    WAN: 192.168.0.3/24
    LAN: 192.168.2.1/24
    Def GW: 192.168.0.1
    NAT for 192.168.2.0/24 to 192.168.0.3

    Both routers would provide DHCP addresses for their respective
    wireless clients. I presume roaming would not work because the client
    would need to obtain a new IP address. But roaming doesn't work now
    anyway as I mentioned yesterday.

    If I'm missing some key point about network connectivity that requires
    NAT for 192.168.0.0/16, I sure wish that someone would enlighten me.
    Bob
     
    Bob Simon, Aug 10, 2008
    #5
  6. Bob Simon

    Stephen Guest

    On Sat, 09 Aug 2008 14:27:53 -0500, Bob Simon <>
    wrote:

    >On Fri, 08 Aug 2008 18:20:05 GMT, Stephen <>
    >wrote:
    >
    >>On Fri, 08 Aug 2008 08:07:47 -0500, Bob Simon <>
    >>wrote:
    >>
    >>>I set up a wireless router in my upstairs home office (providing good
    >>>coverage for the second floor) and a second one downstairs in the
    >>>living room where signal strength is too low to be useful. There are
    >>>probably lots of different ways to do this but I would like feedback
    >>>on the theoretical as well as practical pros and cons of two
    >>>approaches:
    >>>
    >>>1) One wired network (192.168.0.0) connecting the LAN port of the DSL
    >>>modem and the WAN ports of both wireless routers. Each router would
    >>>give out their own small pool of DHCP addresses, 192.168.1.0 upstairs
    >>>and 192.168.2.0 downstairs.

    >>
    >>this one stops you sharing files / printers etc between devices
    >>attached to the 2 routers.
    >>
    >>It is difficult to connect if your modem only has 1 Ethernet port.
    >>
    >>it also breaks down completely if the provider only allows you a
    >>single WAN IP address at a time....
    >>>
    >>>2) The wireless router upstairs would be the only one with DHCP
    >>>enabled and would connect to the one downstairs via the LAN-side
    >>>switch. In effect, this turns the downstairs router into a bridged
    >>>access point.

    >>
    >>this is more common (mainly because SOHO routers are cheaper than
    >>dedicated access points).
    >>You are using the LAN only box as a switch / access point only.
    >>Some boxes have "AP only" mode this as a setup option.
    >>
    >>>
    >>>Are both approaches equally valid?

    >>
    >>no - 1st one doesnt work if you only get 1 address.

    >
    >I hooked up my two routers as per the second design and everything
    >works except roaming. I set the SSID and WEP keys the same and put
    >one router on channel 1 and the other on channel 6. When I go from my
    >upstairs office to the living room, the signal strength meter displays
    >zero or one bar but XP does not switch to the downstairs AP unless I
    >disable or disconnect the wireless connection. When I re-enable or
    >re-connect, I get five bars. Can this switchover be made to occur
    >automatically?
    >
    >Also, I don't understand your comment that my first design won't work
    >because
    >>it also breaks down completely if the provider only allows you a
    >>single WAN IP address at a time....

    >
    >My ISP provides a single public static IP address to the WAN port of
    >the DSL modem. But since this modem does NAT, it should be able to
    >handle mulitple inside hosts with private addresses up to the limit of
    >its ability to handle translations without excessive delay. Right?


    OK - sounds like your "modem" is actually acting as a router.

    However - sharing between the 2 routers with default config will not
    work (since you cannot initiate a TCP connection on 1 and deliver to
    the other if you have NAT on each).

    Try turning off NAT & DHCP on both of your routers and let the modem
    (router) do it.
    --
    Regards

    - replace xyz with ntl
     
    Stephen, Aug 10, 2008
    #6
  7. Bob Simon

    Bob Simon Guest

    On Sun, 10 Aug 2008 16:29:24 GMT, Stephen <>
    wrote:

    >On Sat, 09 Aug 2008 14:27:53 -0500, Bob Simon <>
    >wrote:
    >
    >>On Fri, 08 Aug 2008 18:20:05 GMT, Stephen <>
    >>wrote:
    >>
    >>Also, I don't understand your comment that my first design won't work
    >>because
    >>>it also breaks down completely if the provider only allows you a
    >>>single WAN IP address at a time....

    >>
    >>My ISP provides a single public static IP address to the WAN port of
    >>the DSL modem. But since this modem does NAT, it should be able to
    >>handle mulitple inside hosts with private addresses up to the limit of
    >>its ability to handle translations without excessive delay. Right?

    >
    >OK - sounds like your "modem" is actually acting as a router.
    >
    >However - sharing between the 2 routers with default config will not
    >work (since you cannot initiate a TCP connection on 1 and deliver to
    >the other if you have NAT on each).
    >


    I don't intend to use the default config. Other than that, do you see
    a reason that the first design will not work?

    >Try turning off NAT & DHCP on both of your routers and let the modem
    >(router) do it.


    Is there some reason that a wireless router and the DSL modem cannot
    both do NAT?
     
    Bob Simon, Aug 10, 2008
    #7
  8. Bob Simon

    Merv Guest

    On Aug 10, 3:34 pm, Bob Simon <> wrote:
    > On Sun, 10 Aug 2008 16:29:24 GMT, Stephen <>
    > wrote:
    >
    >
    >
    > >On Sat, 09 Aug 2008 14:27:53 -0500, Bob Simon <>
    > >wrote:

    >
    > >>On Fri, 08 Aug 2008 18:20:05 GMT, Stephen <>
    > >>wrote:

    >
    > >>Also, I don't understand your comment that my first design won't work
    > >>because
    > >>>it also breaks down completely if the provider only allows you a
    > >>>single WAN IP address at a time....

    >
    > >>My ISP provides a single public static IP address to the WAN port of
    > >>the DSL modem. But since this modem does NAT, it should be able to
    > >>handle mulitple inside hosts with private addresses up to the limit of
    > >>its ability to handle translations without excessive delay. Right?

    >
    > >OK - sounds like your "modem" is actually acting as a router.

    >
    > >However - sharing between the 2 routers with default config will not
    > >work (since you cannot initiate a TCP connection on 1 and deliver to
    > >the other if you have NAT on each).

    >
    > I don't intend to use the default config. Other than that, do you see
    > a reason that the first design will not work?
    >
    > >Try turning off NAT & DHCP on both of your routers and let the modem
    > >(router) do it.

    >
    > Is there some reason that a wireless router and the DSL modem cannot
    > both do NAT?


    Double NAT'ing is generally considered troublesome but you can give it
    a try of course

    You should also determine if the wireless routers can be configured as
    bridges and just use 192.168.0.0/24 for the entire setup
     
    Merv, Aug 10, 2008
    #8
  9. Bob Simon

    Stephen Guest

    On Sun, 10 Aug 2008 11:16:19 -0500, Bob Simon <>
    wrote:

    >
    >On Sat, 9 Aug 2008 14:12:46 -0700 (PDT), Merv <>
    >wrote:
    >
    >>> My ISP provides a single public static IP address to the WAN port of
    >>> the DSL modem. But since this modem does NAT, it should be able to
    >>> handle mulitple inside hosts with private addresses up to the limit of
    >>> its ability to handle translations without excessive delay. Right?

    >>
    >>Are you able to configure the DSL modem ?
    >>
    >>If for example the DSL modem is setup to only NAT 192.168.0..0/24 then
    >>you might have an issue ....
    >>
    >>If you can control its configuration so that it will NAT
    >>192.168.0.0/16, then you should be okay

    >
    >The modem is a Motorola/Netopia 2210-02. Motorola tech support said
    >it's been customized per ATT specs with some functionality stripped
    >out. I am able to configure it via the web interface plus via telnet,
    >which offers additional configuration granularity. There is no manual
    >available but the CLI offers help screens and command options. I only
    >see four NAT features:
    > mode -- NAT default server mode
    > mode (off) [ off | default-server | ip-passthrough ]
    > address -- NAT default server IP address
    > dhcp-enable -- NAT IP Passthrough DHCP enabled
    > host-hardware-address -- NAT IP Passthrough host hardware
    >
    >Why would it be useful for the modem to be able to NAT for more than
    >one class c subnet? Wouldn't the following scenario work?
    >
    >DSL Modem
    >WAN: public static
    >LAN: 192.168.0.1/24
    >Def GW: WAN port
    >NAT for 192.168.0.0/24 to public static IP
    >
    >Wireless Rtr 1
    >WAN: 192.168.0.2/24
    >LAN: 192.168.1.1/24
    >Def GW: 192.168.0.1
    >NAT for 192.168.1.0/24 to 192.168.0.2


    if you can disable NAT, then you should be able to get the clients on
    W rtr 1 and w rtr 2 to talk directly.
    >
    >Wireless Rtr 2
    >WAN: 192.168.0.3/24
    >LAN: 192.168.2.1/24
    >Def GW: 192.168.0.1
    >NAT for 192.168.2.0/24 to 192.168.0.3
    >
    >Both routers would provide DHCP addresses for their respective
    >wireless clients. I presume roaming would not work because the client
    >would need to obtain a new IP address. But roaming doesn't work now
    >anyway as I mentioned yesterday.


    OK. if rather than NAT these can work as real routers then you may be
    able to make it work - but the modem would need to handle static
    routes, RIP etc, since your LAN would comprise 3 subnets.

    A better way (especially with only a few devices) is to structure it
    as a single subnet.

    But if the wireless routers just use no NAT, no routing and you have
    DHCP for all devices from the "DSL modem" then a device should be able
    to move across the 2 wireless links using the same IP address.

    So if the address stays the same, you should be able to get roaming to
    work.

    hook a LAN port on each router to the modem.
    Disable NAT / DHCP on each router (or run them in "AP mode" if they
    support it).
    Do not connect to the WAN ports on the routers.
    >
    >If I'm missing some key point about network connectivity that requires
    >NAT for 192.168.0.0/16, I sure wish that someone would enlighten me.
    >Bob


    if you remove 1 layer of NAT you end up witha system with a single
    "LAN" and IP subnet, spread across the modem + 2 routers.

    once you have that the connectivity between your devices is
    unrestricted, and you have a chance to sort out roaming.

    Note - if you want roaming to work, you need:

    1. the same SSID / key phrase / wireless encryption mode on both
    wireless routers.
    2. devices where the wireless driver understand roaming (and
    implements it correctly) - lots of flakey / broken drivers out
    there...
    3. A LAN that handles the logical move of a MAC address - this is
    functions in the bridging within each wireless router + in the modem.

    good luck
    --
    Regards

    - replace xyz with ntl
     
    Stephen, Aug 11, 2008
    #9
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