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Thread: Cisco Cables

  1. #1
    Join Date
    Sep 2004

    Cisco Cables

    Good day!

    I have a 2500 series router and wish to connect to my modem. The serial on the 2500 series is a DB60 and the modem is an RJ45 therfore I am presuming that I will need a male DB60 to female RJ45. Is this correct? Will this allow my 2500 series router to access the WAN? Is there anything that I am missing or should know about? I am new to the Cisco world and currently working towards my CCNA so please excuse me if I'm off track. Any help will be greatly appreciated!

  2. #2
    Senior Member
    Join Date
    Oct 2002
    You should not need the serial port to access the Internet at all. It makes no difference to the router which port traffic arrives on. The serial ports were used because of their transmission rates and stability IIRC.

    There should be three RJ45 ports on the ftont of the router (maybe two). One of these would be used for ingress traffic and the other for egress in your situation, which you mention is a modem. I am assuming this modem is a cable or dsl modem.

    You will have to decide which of these port will connect to your ISP and which one will connect to your internal network. It is likely that your ISP connection will be a DHCP assigned address. Unfortunately I am unaware of how to set up a 2500 as a DHCP client as they were never really intended for this purpose and as such this was not included as part of my CCNA training.

    I can, however, help you with the static setup to some degree, which will apply to your internal interface. You should run the following commands to set up your internal interface. I am assuming that you can already connect to the router and access the Cisco IOS configuration prompt.

    router> enable

    This will put the router into enable mode, which essentially allows you to change all the settings on it.

    router# configure terminal

    This informs the router that you will be changing configuration settings, and is intended as a safeguard against accidental chenges.

    router# interface aux0/0

    I am unsure of the exact interface name for the auxillary port, however it is labelled "aux" on the front of the router. You can also purchase additional cards for the router. Your other ethernet port will be called FastEthernet0/0, meaning card 0, port 0. If there were two ports on this card, the second port would be called FastEthernet 0/1. A second card would be FastEthernet1/0 and 1/1, and so forth.

    router-config# ip address

    This assigns the ip address to the interface

    router-config# no shutdown

    This will enable the interface that you are currently configuring. It actually negates the "shutdown" command, which is issued to all interfaces by default.

    router-config# exit
    router# exit

    Your settings should now be saved to the router's running configuration. To ensure that, if the router must be restarted, that these settings will take effect again, enter

    router# copy running-config startup-config

    And your settings should be saved into the startup configuration.

    To my knowledge, static routing entries are added automatically for each interface as you configure them. If not, you will need to add them yourself. A similar procedure to this will work if your ISP is using static addresses. If they are using DHCP, you will need to determine how to set up the router to accept DHCP address assignments. I know this is possible but unfortunately cannot remember at this time how.

    This should give you a general overview at the very least and get you up and running with this router. I will leave the rest to you to learn on your own. The built in help commands are a great resource to use before you start googling yourself blue in the face.

    It has been some time since I have maintained a switch as this. There may be some errors in this post. I'm sure somebody will catch them if this is the case. Just don't assume that everything here is correct. Most of it is, and hopefully all of it, but you should be able to figure out which parts and improvise where you need to.

    Hope this helps.
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  3. #3
    Join Date
    Sep 2004
    Thanks for the informative response!
    Ok. So set up my WAN to come in on my 2500 through the RJ45 'aux' port. I understand some of what your saying with the commands to do this. I'll see if I can track down the commands for DHCP. Alternativley, is it possible to simply connect it to another router through the aux port before going to the WAN? Such as a d-link or linksys basic soho router that automatically assigns DHCP? Or would it be better to figure out how to do it with the 2500?

    Two more questions:
    The 'AUI' DB12 interface I can use for my LAN, correct? That is to say, plug it into a hub or switch and I'm set. First, I believe I'll need a transceiver to convert it to RJ45 and then I'm good.
    The DB60 serial on the 2500 *which I originally thought I had to connect to the WAN with) I can simply use to connect to my other cisco router, correct?

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