Two inputs into one router?

Discussion in 'Cisco' started by Brian, Jul 6, 2005.

  1. Brian

    Brian Guest

    We need to set up some sort of backup internet service on case our main line
    goes down. We can get a basic DSL line for cheap. So I was wondering if its
    possible to run the DSL connection into a second ENET WIC on our 1721?
    Ideally we would like things to switch over seamlessly, but I don't know if
    its possible through this router?

    Thanks
    Brian
     
    Brian, Jul 6, 2005
    #1
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  2. Brian

    adamclark Guest

    Hi Brian,

    You can run that DSL connection into the ENET WIC, but if you have any
    static routes configured they will not be operational when your primary
    goes down, unless both internet connections are from the same service
    provider.... and I do not suggest you get two connectins from the same
    service provider if you are running mission critical stuff.

    Thanks

    Adam
     
    adamclark, Jul 6, 2005
    #2
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  3. Brian,

    You can put a static default to your main line and a floating
    static to your DSL connection and outbound initiated traffic would be
    taken care of. My concern would be inbound traffic (ie www services,
    etc). Those things have a static IP address and are reached via a DNS
    resolution. The problem is that when your main line fails, you would
    want the DNS resolution for www.yourcompany.com to resolve to an IP on
    your DSL line. I have accomplished this with Cisco CSS' (which are
    expensive), but am not aware of any cheap, simple solution to this
    issue.
    You can also solve this issue with BGP by advertising your subnet
    to two or more providers, but it doesn't sound like that is an option
    for you. (1721, DSL)

    Regards,
    Steve
    www.networking-forum.com
     
    www.networking-forum.com, Jul 6, 2005
    #3
  4. Brian

    Brian Guest

    "www.networking-forum.com" <> wrote
    > You can put a static default to your main line and a floating
    > static to your DSL connection and outbound initiated traffic would be
    > taken care of. My concern would be inbound traffic (ie www services,
    > etc). Those things have a static IP address and are reached via a DNS
    > resolution. The problem is that when your main line fails, you would
    > want the DNS resolution for www.yourcompany.com to resolve to an IP on
    > your DSL line. I have accomplished this with Cisco CSS' (which are
    > expensive), but am not aware of any cheap, simple solution to this
    > issue.


    Thanks for the input. Actually as far as incoming goes, our main concern
    would be email. I think that can be made to work by setting a secondary MX
    record that points to the DSL (we're getting a fixed IP). Run that into the
    router, then to the email gateway.

    Like you said, outbound traffic should be taken care of. I am assuming the
    router can be programmed in some way to use the DSL as a secondary source
    for anything outgoing.

    Thanks
    Brian
     
    Brian, Jul 7, 2005
    #4
  5. Brian

    adamclark Guest

    DUH! I forgot about BGP.... And yeah you could also point your
    secondary MX record to second "backup" connection. Just make sure that
    you have RDNS configured correctly for both connections, which means
    you may have to contact the respective ISPs so that they have you in
    their DNS zone transfer list and they are in yours. If you don't know
    if your RDNS is working, AOL is a great place to try.
    http://postmaster.info.aol.com/tools/rdns.html is a great tool that I
    use when configuring redunant ISP connections to mail servers.
     
    adamclark, Jul 7, 2005
    #5
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