**CISCO** Only 16 VLANS on a 2940? is there a way around?

Posted on 2007-07-24
Last Modified: 2008-01-09
We have 23 vlans currently. We would like to use a couple of little 2940's we have, but they only support 16 vlans, and when i put them into vtp server or client mode they revert to transparent:

SW_VLAN-6-VTP_MODE_CHANGE: VLAN manager chnging device from SERVER to TRANSPARENT.

We only need to use 3 or 4 VLANS on the switches. Is there any way of making this work? I have enabled VTP pruning, but that doesnt seem to have any effect.

Would it work if i manually set the vlans on the local switch
Question by:Wibble_
    LVL 8

    Expert Comment

    Yes it will work make sure the interfaces connected to switches are in trunk mode. Its better if you send the current config to trouble shoot whats the problem is



    Author Comment

    With all due respect, the running config doesn't tell you much about vtp, but here is some more info that might be helpful:

    Maintenance#show running-config                                                
    Building configuration...                                                      
    Current configuration : 994 bytes                                              
    version 12.1                                                                    
    no service pad                                                                  
    service timestamps debug uptime                                                
    service timestamps log uptime                                                  
    no service password-encryption                                                  
    hostname Maintenance                                                            
    enable secret 5 *******                                  
    ip subnet-zero                                                                  
    no ip domain-lookup                                                            
    vtp domain KCS                                                                  
    vtp mode transparent                                                            
    spanning-tree mode pvst                                                        
    no spanning-tree optimize bpdu transmission                                    
    spanning-tree extend system-id                                                  
    interface FastEthernet0/1                                                      
    interface FastEthernet0/2                                                      
    interface FastEthernet0/3                                                      
    interface FastEthernet0/4                                                      
    interface FastEthernet0/5                                                      
    interface FastEthernet0/6                                                      
    interface FastEthernet0/7                                                      
    interface FastEthernet0/8                                                      
    interface FastEthernet0/9                                                      
    interface GigabitEthernet0/1                                                    
    interface Vlan1                                                                
     ip address                                              
     no ip route-cache                                                              
    interface Vlan345                                                              
     ip address                                        
     no ip route-cache                                                              
    ip default-gateway                                                  
    ip http server                                                                  
    line con 0                                                                      
    line vty 0 4                                                                    
     exec-timeout 720 0                                                            
     password *******                                                              
    line vty 5 15                                                                  
     no login                                                                      
    ntp server                                                            
    Maintenance#sh vtp status                                                      
    VTP Version                     : 2                                            
    Configuration Revision          : 0                                            
    Maximum VLANs supported locally : 16                                            
    Number of existing VLANs        : 5                                            
    VTP Operating Mode              : Transparent                                  
    VTP Domain Name                 : KCS                                          
    VTP Pruning Mode                : Disabled                                      
    VTP V2 Mode                     : Disabled                                      
    VTP Traps Generation            : Disabled                                      
    MD5 digest                      : 0x57 0x55 0x2A 0x54 0xA5 0xBD 0xF9 0xCB      
    Configuration last modified by at 0-0-00 00:00:00                      
    Maintenance#sh int status                                                      
    Port      Name               Status       Vlan       Duplex  Speed Type        
    Fa0/1                        connected    1          a-full  a-100 10/100BaseTX
    Fa0/2                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/3                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/4                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/5                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/6                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/7                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/8                        notconnect   1            auto   auto 10/100BaseTX
    Fa0/9                        disabled     1            full    100 100BaseFX    
    Gi0/1                        connected    trunk      a-full a-1000 1000BaseSX  
    Maintenance#sh cdp n                                                            
    Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge        
                      S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone      
    Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID    
    BBone2           Gig 0/1            162          S I      WS-C3550-1Gig 0/6    

    Maintenance#sh ver                                                              
    Cisco Internetwork Operating System Software                                    
    IOS (tm) C2940 Software (C2940-I6Q4L2-M), Version 12.1(22)EA6, RELEASE SOFTWARE
    Copyright (c) 1986-2005 by cisco Systems, Inc.                                  
    Compiled Fri 21-Oct-05 02:01 by yenanh                                          
    Image text-base: 0x80010000, data-base: 0x80572000                              
    ROM: Bootstrap program is C2950 boot loader                                    
    Maintenance uptime is 20 hours, 18 minutes                                      
    System returned to ROM by power-on                                              
    System image file is "flash:/c2940-i6q4l2-mz.121-22.EA6/c2940-i6q4l2-mz.121-22.E
    cisco WS-C2940-8TF-S (RC32300) processor (revision F0) with 20978K bytes of memo
    Processor board ID FOC1024Z478                                                  
    Last reset from system-reset                                                    
    Running Standard Image                                                          
    9 FastEthernet/IEEE 802.3 interface(s)                                          
    1 Gigabit Ethernet/IEEE 802.3 interface(s)                                      
    The password-recovery mechanism is enabled.                                    
    32K bytes of flash-simulated non-volatile configuration memory.                
    Base ethernet MAC Address: 00:18:73:3E:08:C0                                    
    Motherboard assembly number: 73-8783-06                                        
    Power supply part number: 341-0085-01                                          
    Motherboard serial number: FOC10231PJH                                          
    Power supply serial number: HIC1022021C                                        
    Model revision number: F0                                                      
    Motherboard revision number: A0                                                
    Model number: WS-C2940-8TF-S                                                    
    System serial number: FOC1024Z478                                              
    Configuration register is 0xF                              
    LVL 50

    Expert Comment

    by:Don Johnston
    According to this,

    It supports up to 128 VLANs.

    Besides that, why do you need that many VLANs on a 10 port switch?

    Author Comment

    I dont need that many, but our vtp domain has 23. I was guessing that the switch was seeing that it (vtp domain) had too many and then reverting to transparent. I only need access to 2 - 3 on the swith itself. I just cant get the thing to go into client or server mode *sob*.
    LVL 50

    Accepted Solution

    I really don't like VTP. Too many potentials for surprises. And with a switch that small, just put it in Transparent mode and create the VLAN's you need.

    Author Comment

    So that will work then?

    /me dashes off to try...

    It works! Yay!

    Thanks everyone.

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