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Cisco 877W ADSL for Cable

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  • Cisco 877W ADSL for Cable

    Hey,

    I have been using a Cisco 877W on my ADSL line but now I have moved,
    I have a cable service where the presentation is now Ethernet on the WAN side.

    Is it possible to configure one of the Ethernet ports on the back of the 877 to be WAN port as I don't really want to buy another 877 just to get Ethernet on the WAN.

    Cheers

    Pete.

  • #2
    Re: Cisco 877W ADSL for Cable

    Yes, assuming your cable modem can present an ethernet interface to the router, it should be possible.

    Exactly how you'd do it i'm not 100% on the IOS commands.. but ideally you'd make the cable modem do all the authentication, and just bring up an ethernet interface on the 877, then tell the 877 that the default route is fe0 or whatever


    that's the beauty of the cisco gear.. it's just an ethernet port - you can do whatever you want, provided the equipment at te other end can talk what you're telling it to talk.. you can route anything down anything.. you can prevent something from fe0 from traversing to fe1 or dialer0, or which ever.
    Please do show your appreciation to those who assist you by leaving Rep Point https://www.petri.com/forums/core/im.../icon_beer.gif

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    • #3
      Re: Cisco 877W ADSL for Cable

      Hey tehcamel,

      That all makes sense. The cable modem seems to handle all the authentication details and the device on the end of the Ethernet interface gets the External IP address.

      The only problem I can see is that the 4 Ethernet interfaces are configured to be a switch together with the Wireless interface, i believe this is done via the BVI interface.

      Code:
          
      interface BVI1
           description $FW_INSIDE$
           ip address 192.168.0.1 255.255.255.0
           ip access-group 100 in
           ip nat inside
           ip virtual-reassembly
      As the Ethernet interfaces are not configured.
      Code:
          !
          interface FastEthernet0
          !
          interface FastEthernet1
          !
          interface FastEthernet2
          !
          interface FastEthernet3
      If i were to configure one with NAT and to get the IP address etc.. would it take it out of the switch to be an independent Ethernet interface?

      And would the wireless still work to client connected to the other Ethernet ports.

      Cheers

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      • #4
        Re: Cisco 877W ADSL for Cable

        Bump______

        Comment


        • #5
          Re: Cisco 877W ADSL for Cable

          Can you configure the four ethernet ports as a VLAN, so they are all handled as single entity?

          Jim

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          • #6
            Re: Cisco 877W ADSL for Cable

            That's how that are already configured.

            But that seems to be done all via the BVI interface.

            I'm wondering that as they dont have a layer 3 commands the router is just running them as a switch as you can plug a device into any of the Ethernet ports and access network.

            My Question is that if I just configure one of the Ethernet interface will that just break it off what appears to be a switch.

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