vlans limit on 2950

[mateomateo1]

Hi,

I have 10 2950 switches on my network that support only 64 vlans on each one.  I actualy have requrement to cleate around 100 vlans acros them, can I switch off vtp and create required vlans manualy or is there any other solution to solve that?

I will have more or less following set up:

router

   |

2950 - vlan 1,2,3,4,5,6,7,8,9,10

   |

2950 - vlan 11,12,13,14,15,16,17

   |

2950 - vlan 18,19,20,21,22,23,24

   |

2950 - vlan 25,26,27,28,29,30

   | 

2950 - etc...

   |

2950 - etc...

.... etc.

[smitesh kharecha]

Hi Matt,

What version of IOS you are running ??

As now modern IOS support all the normal VLANs...

Yes, if VTP is in transparent mode, you can create all other extendend Vlans too...

But, my concern will be still the version of IOS you are using...

HTH,

Smitesh

PS: Please rate helpful posts...

[mateomateo1]

Hi and thank you for the reply,

I am not in the office at the minute but one of the switch is with 12.1(22)EA4

Can I not just create my 100 vlans manualy?

[Sandeep Choudhary]

Hi Matt,

Catalyst 2950 switches that run the standard software image (SI) support 64 VLANs;

Catalyst 2950 and Catalyst 2955 switches that run the enhanced software image (EI) support 250 VLANs.

just check which one you have,

Regards

please rate if its helpful

[mateomateo1]

Hi,

I know that it support only 64 vlans, but I think that 64 vlans are for one switch only, so If I set all up manualy, I can have whatever vlans I want (limited by port no.)

[Sandeep Choudhary]

As per my knowledge, if you want to create 100 vlan then you have to update your Software image.

Regards

please rate if its helpful

[mateomateo1]

can anyone confirm that?

[smehrnia · Accepted solution]

hi,

I believe if you set your vtp mode to transparent, you can manually create vlans on each switch as you showed earlier, with no problem.

regarding to your requirement, you need 10 vlans on each switch, so no problems. As for the traffic switching, your Trunk ports will just read the Vlan ID and if it is allowed (which by default it is) passes the traffic to its next hop, so forth.

no problem if VTP mode: Transparent.

plz Rate if it helped.

Soroush.

[mateomateo1]

what is the point of limiting vlans to 64 only?

switches stacking, support of stp?

[Sandeep Choudhary]

HI matt..this is regading with STP:

Catalyst 2950 switches that run the standard software image (SI) support 64 VLANs; Catalyst 2950 and Catalyst 2955 switches that run the enhanced software image (EI) support 250 VLANs. Refer to the release notes for the list of switches that support each image. VLANs are identified with a number from 1 to 4094 when the EI is installed and 1 to 1005 when the SI is installed. VLAN IDs 1002 through 1005 are reserved for Token Ring and FDDI VLANs. VTP only learns normal-range VLANs, with VLAN IDs 1 to 1005; VLAN IDs greater than 1005 are extended-range VLANs and are not stored in the VLAN database. The switch must be in VTP transparent mode when you create VLAN IDs from 1006 to 4094.

The switch supports per-VLAN spanning-tree plus (PVST+) and rapid PVST+ with a maximum of 64 spanning-tree instances. One spanning-tree instance is allowed per VLAN. See the "Normal-Range VLAN Configuration Guidelines" section for more information about the number of spanning-tree instances and the number of VLANs. The switch supports IEEE 802.1Q trunking for sending VLAN traffic over Ethernet ports.

The switch supports 64 spanning-tree instances. If a switch has more active VLANs than supported spanning-tree instances, spanning tree can be enabled on 64 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 STP instance.

Regards

please rate if it helps.

[smehrnia]

Matt, right now i couldnt think of any special reason behind the 64 vlan limit, but my guess would be first the business aspect of it, if you need to implement a bigger network you pay more for a more advanced device.

second it'd be hardware limitation, coz with bigger vlan size naturally comes more data traffic and services, etc. that this switch might not be capable of handling.

well, that is all i can think of.

[Sandeep Choudhary]

Hi Matt,

finally got gud news for you.

You can create 100 vlan but you have to put switch in to Transparent mode.

just to avoid confusion: setting a switch to transparent will stop all VTP advertisements and make the switch effectively a standalone switch, with all the additional administrative overhead. I would not recommend it, unless you really need more than 64 VLANs on your 2950, which is actually not likely.

Regards

please rate if its helpful

[glen.grant]

  It depends on how your net is setup .  If they all have individual uplinks  to the main  L3 device then creating  vlans on the 2950 should work in transparent.   If they are daisy chained then it could be a problem because all switches will have to carry all vlans of the switch below it .