VLAN traffic thru layer 2 and 3 switch

Answered Question
Sep 20th, 2007
User Badges:

Can I pass traffic for two different VLAN's through a layer 2 switch to a layer 3 switch? I have a management server on VLAN 1 which needs to access servers on two other seperate vlans. They all end up at the layer 3 switch but I cannot connect. See the attached diagram.

Thanks

Chris



Correct Answer by Jon Marshall about 9 years 10 months ago

Chris


No problem, glad to have been of help.


Just to clarify.


Vlans do not need a layer 3 switch. You can create multiple vlans on a layer 2 switch and allocate ports on that switch into different vlans. When you create these vlans you are creating them a layer 2 only.


However if you want to route between the vlans then you need L3 interfaces for the vlans which can either be on a standalone router or on a L3 switch. If you create them on a lyer 3 switch you still need to create the vlan at layer 2 on that switch as well.


HTH


Jon

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Loading.
Jon Marshall Thu, 09/20/2007 - 07:58
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Chris


I can't open your visio as i don't have it on my home PC so forgive me if i have misunderstood anything.


Yes you can pass traffic for multiple vlans from a layer 2 switch to a lyer 3 switch.


You need to connect your layer 2 switch to your layer 3 switch with a trunk link which can carry traffic for multiple vlans.


On the layer 3 switch you create the layer interfaces ( SVI's ) for the vlans so that you can route between vlans.


HTH


Jon

olsonc0510 Thu, 09/20/2007 - 08:11
User Badges:

Jon, here it is in PDF format. Note I am not using a single link from the layer 2 switch. I have one link for each vlan on the layer 2 switch connecting to a port on the layer 3 switch corrosponding to the specified vlan. The layer 2 switch has no IP address and no vlan info on it. Is that required?



Jon Marshall Thu, 09/20/2007 - 08:19
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Hi


Well it's a little unusual but there is no reason why it would not work.


So on the 6500 you have 3 L3 interfaces ie.


int vlan 1

ip address x.x.x.x "subnet mask"


int vlan 2

ip address x.x.x.x "subnet mask"


int vlan 3

ip address x.x.x.x "subnet mask"


And each of the clients in the vlans point to the vlan ip address on the 6500 as their default-gateway.


If so this should work. Can you check the status of your vlan interfaces on the 6500


sh ip int brief


Are they all showing as "up up"


Also have you created the relevant layer 2 vlans on each switch ?


Jon

olsonc0510 Thu, 09/20/2007 - 08:31
User Badges:

Thanks. I can change this config and simply trunk to the 6509. However, I have not created the layer 2 vlans on the layer 2 switch. I didn't realize this had to be done. I was under the impression that vlans required a layer 3 switch. Now I am starting to see the problem. We've had a flat network up until now so I am a newbie when it comes to implementing VLANS. We've been using the FW rather than the 6500 as the default gateway. I'll need to change that.

You've been a big help!

Chris

Correct Answer
Jon Marshall Thu, 09/20/2007 - 09:11
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Chris


No problem, glad to have been of help.


Just to clarify.


Vlans do not need a layer 3 switch. You can create multiple vlans on a layer 2 switch and allocate ports on that switch into different vlans. When you create these vlans you are creating them a layer 2 only.


However if you want to route between the vlans then you need L3 interfaces for the vlans which can either be on a standalone router or on a L3 switch. If you create them on a lyer 3 switch you still need to create the vlan at layer 2 on that switch as well.


HTH


Jon

Actions

This Discussion