2960 LAN Lite, VLAN number max 64

[Paolo Piutz]

Hi,

we have inserted into a network with VTP a Cisco Switch 2960-S, not knowing that had installed IOS LAN lite.

Now I discovered that it can handle up to 64 vlan. In the network there are currently configured 62 VLAN: what happens when we exceeded the max number

(64) of VLAN for that switch?

Thank you.

Paolo.

[Reza Sharifi]

Hi,

If you try to go above 64, you get an error message saying that it is not supported.

Up to 64 VLANs and up to 64 spanning-tree instances per switch are supported

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/product_data_sheet0900aecd806b0bd8.html

HTH

[Paolo Piutz]

Ok,

over the error message, something else will happen? The switch LAN lite crash or work fine whit the first 64 VLAN, or something like that?

Thank you.

Paolo.

[Reza Sharifi]

It will work fine with first 64 vlan. If you try 65. it will give an error message, but the switch will not crash.

HTH

[glen.grant]

   Why do you need 64 vlans on a small switch like that ?   If you are talking vtp and the max spanning tree instances then all that needs to be done is  manually prune off any vlans not needed on the switch by using the "switchport trunk allowed vlan "  on each side of the uplink .  You prune off anything that is not needed on that switch .  If you only need say vlan 3,4,5  then use switchport trunk allowed vlan 3,4,5 on the uplinks.

[Paolo Piutz]

Hi, a small summary:

we manage a star topology with a 6509 as the central switch: this is the root bridge for STP and the server for the VTP. We have also 6506 installed in important nodes.

On the edge of the star we usually install  WS-C2960-24TC-L as periferic devices. This switch have a LAN Base IOS that can manage up to 255 VLAN. Without a preliminary check, we purchased the 2960-S.

Obviously not all vlan are needed in each site: so if I well understand, it's possible to permit only vlan needed on the specific site, on the each side of uplink, to bypass the problem, right?

Otherwise, to not change switch model, I thought,to configure it in trasparent mode.

Thank you.

WS-C296 vlan 0-24TC-L

[Reza Sharifi]

Paolo,

From your description, you are using 24 port switches.  If you put every single port in a different vlan, the max number of vlans is 24.  Even if you use POE with separate vlans for phone, the max number of vlan is 48.  The only place you can exceed this number is in a data center, where the ports are trunked to servers which will Cary multiple vlans.

So, lets say you have 10 switches connecting to your core 6500 and each with 20 vlans (10 vlan for data and 10 for voice) then you only allow these 20 vlans on the trunk of each 2960 switch, which is a lot less then 64.

HTH

[amir rostami]

Hi Dear Sharifi,

I've made some practical tests.

As you definitely know, VLAN numbers and names would be transported via VTP messages.

Those messages are multicast layer-2 messages and would not be related to how many vlans are allowed on trunk ports.

Maximum vlans in LAN lite (2960pc-s) in vtp client mode is 64 (instead of 1002 numbers in LAN base switches like 2960-24TC-L)

Below pictures would illustrate, 

Even with vlan numbers below 64 on trunk link, VTP mode translate to "Transparent"

 IOS 12.2(55)SE12 is the latest and recommended version supported.

Cisco switche model and IOS

[Paolo Piutz]

Thank you to all,

I would like to come to an happy end....;)

In my network configuration we have more then one site where will not need all vlan propagated by VTP.

So I can use some LanLite switch with the uplink trunk port configured "switchport trunk allowed vlan" without problem?

Thank you in advance.

Paolo.

[Paolo Piutz]

Ok

I've maked some test:

if I exceed the maximum number of vlan, the lanlite switch automatically becomes in "transparent mode" even if I configure the uplink port with the "switchport trunk allowed vlan" command.

There is no way so, you can use it in "client mode" if I exceed the 64 vlan.

Bye.

Paolo.