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2586 Views 5 Replies Latest reply: Sep 11, 2011 8:07 AM by Jared RSS

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Switch 2950 and 3750 Question

Sep 9, 2011 7:23 AM

Vivek Nagar 157 posts since
Jan 25, 2010

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

  • Currently Being Moderated
    1. Sep 9, 2011 7:29 AM (in response to Vivek Nagar)
    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?

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  • Jared 5,547 posts since
    Jul 27, 2008
    Currently Being Moderated
    5. Sep 11, 2011 8:07 AM (in response to Vivek Nagar)
    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.

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