Re: 1024 VLAN support in 2960?

arun kumar · ‎07-19-2010

Hi All,

I would like to know if there is any IOS currently avaialble for Cisco 2960 switch (WS-C2960-24TT-L) which will support maximum VLAN's of 1005 (or more than 255). Currently the switch supports 255 VLAN's. Wanted to know this limit is controlled by hardware of IOS.

Because sometime back 2950 switches were supporting only 64 VLAN's and there was an IOS which increased the max VLAN to 255.

thanks in advance

Arun

Leo Laohoo · ‎07-19-2010

12.2 IOS will support Extended VLAN.

12.1 IOS (version which the 2940/2950/2955 runs on) will support Extended VLAN starting from EA9.

Hope this answers your question.

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arun kumar · ‎07-19-2010

Hi

Thanks for your reply. But I think I wasn't clear in my question and apologies for that. I wanted to know about the maximum number of VLAN's supported in 2960 (not on supporting standard and extended VLAN ranges). My requirement is to have more than 255 number of VLAN's in 2960 but the IOS that i am running currently does not support more than that. So any IOS that supports more than 255 number of VLAN's in 2960?

thanks

Arun

thinakraj · ‎07-20-2010

for 2960 will support only 255 vlans in vtp client /server and transparent modes.

Follow these guidelines when creating and modifying normal-range VLANs in your network:

•The switch supports 255 VLANs in VTP client, server, and transparent modes.

•Normal-range VLANs are identified with a number between 1 and 1001. VLAN numbers 1002 through 1005 are reserved for Token Ring and FDDI VLANs.

•VLAN configuration for VLANs 1 to 1005 are always saved in the VLAN database. If the VTP mode is transparent, VTP and VLAN configuration are also saved in the switch running configuration file.

•The switch also supports VLAN IDs 1006 through 4094 in VTP transparent mode (VTP disabled). These are extended-range VLANs and configuration options are limited. Extended-range VLANs are not saved in the VLAN database.

•Before you can create a VLAN, the switch must be in VTP server mode or VTP transparent mode. If the switch is a VTP server, you must define a VTP domain or VTP will not function.

•The switch does not support Token Ring or FDDI media. The switch does not forward FDDI, FDDI-Net, TrCRF, or TrBRF traffic, but it does propagate the VLAN configuration through VTP.

•The switch supports 128 spanning-tree instances. If a switch has more active VLANs than supported spanning-tree instances, spanning tree can be enabled on 128 VLANs and is disabled on the remaining VLANs. If you have already used all available spanning-tree instances on a switch, adding another VLAN anywhere in the VTP domain creates a VLAN on that switch that is not running spanning-tree. If you have the default allowed list on the trunk ports of that switch (which is to allow all VLANs), the new VLAN is carried on all trunk ports. Depending on the topology of the network, this could create a loop in the new VLAN that would not be broken, particularly if there are several adjacent switches that all have run out of spanning-tree instances. You can prevent this possibility by setting allowed lists on the trunk ports of switches that have used up their allocation of spanning-tree instances.

If the number of VLANs on the switch exceeds the number of supported spanning-tree instances, we recommend that you configure the IEEE 802.1s Multiple STP (MSTP) on your switch to map multiple VLANs to a single spanning-tree instance.

milan.kulik · ‎07-20-2010

Hi,

do you really need more than 255 VLANs on an low-end switch like 2960?

It must be a really interesting LAN design!

But a nightmare from an admin point of view?

BR,

Milan

glen.grant · ‎07-20-2010

Why would you need that many vlans on a switch that has 48 ports ??

Leo Laohoo · ‎07-20-2010

My requirement is to have more than 255 number of VLAN's in 2960 but the IOS that i am running currently does not support more than that.

It's called EXTENDED VLAN.

arun kumar · ‎07-21-2010

Hi Glen and Milan - Yes though it a low end switch we have a strange requirement where 2960 should support more than 255 number of VLAN's. Else we need to upgrade the hardware to support this.

Hi Leo - I think there is a difference between the maximum number of VLAN's supported and standard and extended VLAN ranges. What i needed is the maximum number of VLAN's supported in 2960 (i need more than 255 number of VLAN's) and not the extended VLAN support.

thanks

Arun

milan.kulik · ‎07-21-2010

Hi Arun,

I'd say: Instead of finding a low-end switch supporting a huge number of VLANs, shouldn't you try to change your LAN design not to carry so many VLANs in the access layer?

Don't forget another insidious Cisco low-end switch feature: They usually support even lower number of STP instancies :-(

(It was mentioned in one of the comments above 2960s support only 128 STP instancies.)

BR,

Milan

Leo Laohoo · ‎07-21-2010

All switches from the 2940/2950/2955 and later will support standard VLAN, 255 VLANs. If you want more, it's called Extended VLAN and yes, the 2960 support that too.

milan.kulik · ‎07-21-2010

Hi Leo,

I'm afraid you might be mixing two things here:

1) Extended VLAN ID support.

This feature allows you to configure VLAN IDs 1006 to 4094 on your device.

(see http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/ht_xvlan.html#wp1064990)

2) The number of VLANs (VLAN instancies) you can configure on your switch (using the standard or extended ID range).

Which is 255 for 2960s.

BR,

Milan

Leo Laohoo · ‎07-21-2010

I'm afraid you might be mixing two things here:

Nuts. Mea culpa.