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  • catalyst 2950 vlan problems..

    hi guys, i am having a problem with the vlans in a router-on-a-stick configuration.
    i have 2 extra vlans configured (plus the native vlan 1) and a few ports assigned to each, with the problem being that every time i bring one of the vlans up using a "no shutdown" the other vlan currently up goes down.
    please help, as i am dumbfounded, i have done this in virtual many times and was always successful, this time i am using a real 2950 and 2620.

    a show run is attached.

    can someone help?
    Attached Files

  • #2
    Re: catalyst 2950 vlan problems..

    You can't do this on a layer 2 device. Only one interface VLAN is allowed.
    Create a trunk (.1q) port between the 2 devices.

    Please review: http://www.tech-recipes.com/rx/1853/...er_on_a_stick/
    Marcel
    Technical Consultant
    Netherlands
    http://www.phetios.com
    http://blog.nessus.nl

    MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
    "No matter how secure, there is always the human factor."

    "Enjoy life today, tomorrow may never come."
    "If you're going through hell, keep going. ~Winston Churchill"

    Comment


    • #3
      Re: catalyst 2950 vlan problems..

      dumber, thanks for this, but i think i might not have explained myself well enough.
      the very same configuration was built in packet tracer using the same devices.
      for some reason it works well there.
      i was able to create the vlans an assign ports to them, and i have a dot1q trunk port to a router.
      at any given time only 1 vlan can be up, as when i do a "no shutdown" command on the vlan interface (which is down) it goes up and the switch brings the vlan which was up before down.

      are you saying that i can only have 1 active vlan on a 2950?
      this seems strange as in packet tracer it is configurable and working.

      please help..
      Last edited by purefog; 5th April 2010, 23:28. Reason: נ.ב

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      • #4
        Re: catalyst 2950 vlan problems..

        Yes you can using the command vlan database but you cannot create muliple VLAN interfaces on the 2950.
        Marcel
        Technical Consultant
        Netherlands
        http://www.phetios.com
        http://blog.nessus.nl

        MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
        "No matter how secure, there is always the human factor."

        "Enjoy life today, tomorrow may never come."
        "If you're going through hell, keep going. ~Winston Churchill"

        Comment


        • #5
          Re: catalyst 2950 vlan problems..

          so, the trunk will be operational but i will not be able to ping the IP addresses of the vlans, only devices connected.
          is this true?

          Comment


          • #6
            Re: catalyst 2950 vlan problems..

            The devices will be able to ping it's default gateway of the router. So you will be able to ping the VLAN ip addresses, but on the router and not on the switch. If you want to do this you need a layer 3 switch (for example a 3750 or so). In that case you can configure multiple VLAN interfaces and configure inter-routing without using a router on a stick.
            Marcel
            Technical Consultant
            Netherlands
            http://www.phetios.com
            http://blog.nessus.nl

            MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
            "No matter how secure, there is always the human factor."

            "Enjoy life today, tomorrow may never come."
            "If you're going through hell, keep going. ~Winston Churchill"

            Comment


            • #7
              Re: catalyst 2950 vlan problems..

              The 2950 isnt layer 3 capable so like OP said you need an external router to route between your vlans or get a L3 capable switch and create SVI's for you vlans and set you clients default gateway to the appropriate SVI.
              CCNA, CCNA-Security, CCNP
              CCIE Security (In Progress)

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