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Can Cisco router separate 2 networks??

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  • Can Cisco router separate 2 networks??

    I have a cisco 2500 router at home and im trying to build a lab to simulate a same business network.

    I thought the idea of routers was to block broadcasts and connect to other networks.

    I see I can hook a switch up to its one port and a modem or what not to another port. I thought the idea was it would have a few nics built in to connect other networks to otherwise I can just plug the switch straight into my wan device.

    Whats the point then of this router.

    Id like to separate two networks e.g. network 1 192.168.0.x & network 2 192.168.1.x and use the router(I have 2 of them) to accomplish this.

    Guess im a little confused as I couild have a PC with 2 nics and routing software, but then I have a network device that is a dedicateed router and it cant do this! can it?

    Thanks for reading.

  • #2
    Re: Can Cisco router separate 2 networks??

    it depends on the interfaces within the router itself..
    depending on your 2500 model, it's probably only got one Ethernet interface.

    So you'd use it to route from the ethernet interface, to a network device connected on one of the Serial ports for instance

    If you get something that has two Eth interfaces you'll be able to route between ethernet interfaces..
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    • #3
      Re: Can Cisco router separate 2 networks??

      Not to be flip, and this isn't an answer to your question, but routers by nature and purpose separate two networks (at the very least). Sometimes they separate more than two networks. A router in it's simplest form has a WAN interface (external network) and a LAN interface (internal network) providing "separation" of the two networks.


      • #4
        Re: Can Cisco router separate 2 networks??

        hacving re-read your post, I think this may assist.

        You have two routers, and two networks. ( and for instance)

        On R1, configure the Ethernet interface for network
        On R2, configur the Ethernert interface for network.

        Ok, great.. so now, your two networks are separated.. and controlled by routers.
        so, you need to link the two.

        (btw, this is cisco CCNA1 basic training)
        what you need to do now, is use the serial interfaces, to create another network.
        Let's call it
        So on R1, configure the serial interface for
        and on R2, configure the serial interface for

        Now, ensure that the link is coming up, and the two routers are at least aware of each other.

        Now, you need to look at creating proper routing entries (using RIP, OSPF, or whatever) so that knows how to get to
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        • #5
          Re: Can Cisco router separate 2 networks??

          Also for connecting the routers back to back you will need a serial cable. Pay attention to the DCE and DTE sides. The DCE end connection to the serial interface will provide the clocking for the circuit.

          clockrate 64000 etc

          You can check with side is the DCE/DTE using the command:

          show controller s0/0 etc
          Last edited by auglan; 15th February 2012, 14:54.
          CCNA, CCNA-Security, CCNP
          CCIE Security (In Progress)


          • #6
            Re: Can Cisco router separate 2 networks??

            I see. So in this case I need 2 physical routers and a DCE cable to seperate 2 networks ! ! Or perhaps twould be more cost effective to purchase a module that gives an extra nic so that we can hook another network to it.

            It seems crazy having to purchase all that equipment for such a task. Im not a cisco person but I do want a beginners understanding of networking equipment. In my case Ill do as you lads say as I just want the practice. The clocking dce dte dosent that simulate a WAN link between the networks e.g. t1 connection??

            This makes me wonder how then are networks/Lan's separated typically in meduim companies?? Is it cisco boxes or linux software on a pc, hardly ms server used for this task?

            Thank you


            • #7
              Re: Can Cisco router separate 2 networks??

              The 2500's have been end of life for some time now. Most only came with 1 ethernet port and its a 10mbp port. I still have some 2500's that require the AUI transceiver (has dip switches on it) which will convert it to an ethernet interface. For basic commands they are fine but you may consider looking at the 2610xm's or 2621xm's. You could buy another ethernet card for the 2500 but it would have to have a slot in the router for the card. Not all 2500's support additional slots. Yes the back to back connection could simulate a point-to point hdlc link. ppp link or frame relay. Having actual equipment is good and there is no substitute for it but have a look at GNS3 which is a cisco IOS emulator. It cant run the new code 12.15 etc but supports a bunch of router models (2600,3600,3700 etc). Just google gns3.

              My network where I work is totally cisco from switches to routers and firewalls. Other's may like Juniper etc.

              You can also use layer 3 switches to segment your routing domain (3550's, 3560's 3750's etc)
              CCNA, CCNA-Security, CCNP
              CCIE Security (In Progress)