5 Replies Latest reply: Sep 11, 2011 8:07 AM by Jared RSS

    Switch 2950 and 3750 Question

    Vivek Nagar

      Hi friends,


      please can you resolve my to queries


      1.  if we have switch 2950 with vlan 1 as a managemnt vlan (With IP address )and we create vlan 20 layer 2 and then created layer 3 SVI interface , then vlan  1 automatically admin shut down.


      if we un shut the vlan 1 interface then both the vlan up (is it true .....) if true then how possible then layer 2 switch has two management IP's


      2. second


      cisco 2950 connected with cisco 3750 switch with f0/24 for both side.


      2950----f0/1--------f0/1 -----3750


      for 2950

      we have a vlan 1 and 20 (voice vlan) with SVI interfaces

      like vlan 1 IP add

      and vlan 20 ip add


      only interface f0/24 has config

      switch mode access

      switch voice access vlan 20


      as when we create vlan 20 SVI then vlan 1 auto shut so output for sh ip int brief shows vlan 1 admin down and vlan 20 protocol down


      now can it possible that we can access this switch from 3750 (vlan 1 -- ip add and vlan 20 --ip add

      what is the config on f0/1 to access the switch 2950


      i have tried trunk access as well as trunk but not accessable.


      or we need console for 2950 to change the configuation.




      Vivek Nagar

        • 1. Re: Switch 2950 and 3750 Question

          The 3750 should support MLS - configure your SVIs on that switch.  2950s only support a single SVI with an IP - it is NOT multi-layer switching capable.  Each time you "no shut" an SVI with an IP on it, the current one will shut down. 


          With that said, ensure "ip routing" is turned on the 3750, ensure MLS is on(depending on the code you're running), then configure all of your SVIs on the 3750.  Once that is done, create a dot1q trunk to the 2950 and ensure the VLANs(NOT SVIs, VLANS) are created ont he 2950. 


          Does that make sense?

          • 2. Re: Switch 2950 and 3750 Question
            Vivek Nagar

            Hi Travis,


            Thanks your anwser but  it just a confusion with me as i know in layer 2 switch like 2950 , if we created 2 svi at a time only one is up.


            and cisco 2950 is not able to access our firend has done above config but now he is not avalible on site and i have only access on cisco 3750, can it possible i can access from cisco 3750 to 2950 ..

            • 3. Re: Switch 2950 and 3750 Question
              Vivek Nagar

              I can  not do any config on cisco 2950 (old config on interface is given above 

              only interface f0/24 has config

              switch mode access

              switch voice access vlan 20

              vlans vlan 1 and 20 layer 2

              vlan 1 and 2 layer 3 as well (due to misconfig by friend).


              it is not reachable from my side only 3750 reachable.

              any debug which give information above neighbour interface configuration (as we not see in cdp as well ----cdp is already enable)

              • 4. Re: Switch 2950 and 3750 Question
                Vivek Nagar

                any one have any solution for this.





                • 5. Re: Switch 2950 and 3750 Question

                  Travis's post is the answer you are looking for.  Layer 2 switches can only have 1 svi up at a time.  What ever Vlan you want the management ip of your switch to reside in is the sci the switch needs to have.  There is no need to have multiple svi's on a layer 2 switch. 

                  In my case I will usually have 3 vlans on a switch.  A data Vlan, a voice Vlan and a management Vlan.  The switches svi would be on the management Vlan and then car layer 2 vlans for voice and data.