Can I use old router as network hub/switch ?

Discussion in 'Network Routers' started by Ken Smith, Mar 29, 2008.

  1. Ken Smith

    Ken Smith Guest

    I want to attach some network storage to my existing network but I am
    already using all the available LAN ports on my current router.

    I have an old spare router.
    Can I take a LAN connection from my current router into the WAN socket of my
    old router and then use the 4 LAN sockets on the old router to expand my
    network ?

    Just wondering if this is viable before starting to waste time & effort.
     
    Ken Smith, Mar 29, 2008
    #1
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  2. Ken Smith

    Bruce Guest

    I would hook it into one of the LAN ports instead. Turn off DHCP in the
    router and just use it as a 3 port switch.

    Thanks,
    Bruce
     
    Bruce, Mar 29, 2008
    #2
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  3. Ken Smith

    News Reader Guest

    If you do that you will have two separate networks (each with their own
    IP address space), separated by the newly implemented spare router
    (downstream router).

    You would need to configure the pre-existing router (upstream router)
    with a static route so that it knows how to reach the new network on the
    downstream side of the downstream router.

    If a host on the upstream network needs to connect with a host on the
    downstream network, it will forward the first packet to its default
    gateway (upstream router). The upstream will check its route table and
    determine that it is necessary to forward the packet to the downstream
    router in order to reach the downstream host. It will then forward the
    packet.

    The upstream router then sends an ICMP message to the upstream host
    saying "use the downstream router to reach the downstream host, it has a
    better route than I do". The upstream host should then add a route to
    its local routing table, modify its behavior, and send subsequent
    packets directly to the downstream router to reach the downstream host.

    Furthermore, you would need to configure the WAN interface on the
    downstream router to permit communication from upstream hosts, to
    downstream host.

    It's a bit more involved than adding a switch isn't it?

    If you were to connect the LAN interface of the spare router to the LAN
    interface of the pre-existing router you would achieve what you are
    after, but there are precautions that must be taken.

    You need to ensure that the web management interfaces of the two routers
    are not using the same IP address BEFORE connecting them together. You
    would also want to disable the DHCP server on the spare router. You may
    or may not need a crossover cable to connect the two routers via their
    LAN interfaces depending on their capabilities.

    Best Regards,
    News Reader
     
    News Reader, Mar 29, 2008
    #3
  4. Ken Smith

    News Reader Guest

    Make sure the two routers are not using the same web administration IP
    address BEFORE connecting the two devices.

    Best Regards,
    News Reader
     
    News Reader, Mar 29, 2008
    #4
  5. From: "News Reader" <>

    | If you do that you will have two separate networks (each with their own
    | IP address space), separated by the newly implemented spare router
    | (downstream router).
    |
    | You would need to configure the pre-existing router (upstream router)
    | with a static route so that it knows how to reach the new network on the
    | downstream side of the downstream router.
    |
    | If a host on the upstream network needs to connect with a host on the
    | downstream network, it will forward the first packet to its default
    | gateway (upstream router). The upstream will check its route table and
    | determine that it is necessary to forward the packet to the downstream
    | router in order to reach the downstream host. It will then forward the
    | packet.
    |
    | The upstream router then sends an ICMP message to the upstream host
    | saying "use the downstream router to reach the downstream host, it has a
    | better route than I do". The upstream host should then add a route to
    | its local routing table, modify its behavior, and send subsequent
    | packets directly to the downstream router to reach the downstream host.
    |
    | Furthermore, you would need to configure the WAN interface on the
    | downstream router to permit communication from upstream hosts, to
    | downstream host.
    |
    | It's a bit more involved than adding a switch isn't it?
    |
    | If you were to connect the LAN interface of the spare router to the LAN
    | interface of the pre-existing router you would achieve what you are
    | after, but there are precautions that must be taken.
    |
    | You need to ensure that the web management interfaces of the two routers
    | are not using the same IP address BEFORE connecting them together. You
    | would also want to disable the DHCP server on the spare router. You may
    | or may not need a crossover cable to connect the two routers via their
    | LAN interfaces depending on their capabilities.
    |
    | Best Regards,
    | News Reader
    |

    Not needed if the WAN port isn't used and the DHCP server is disabled.
     
    David H. Lipman, Mar 29, 2008
    #5
  6. Ken Smith

    CWatters Guest

    In other words the WAN port is left unconnected and everything is connected
    to LAN ports including the wire to the existing router. The firewall in the
    new router isn't used and everything appears on the same network. DHCP is
    turned off in the second router as you only want one issuing IP addresses.
     
    CWatters, Mar 29, 2008
    #6
  7. Ken Smith

    Ken Smith Guest

    Thanks to everybody for the information & suggestions.
    Much appreciated.

    Ken
     
    Ken Smith, Mar 30, 2008
    #7
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