Switch Ports flapping

[jamesy_281]

Hi There,

I'm studying for my CCNA and I'm using boson Netsim 8 to try and expriment with setting up VTP. I have two 2960 switches and a 2811 router in the test lab.

I have configurd the the trunk links and  VTP OK but there are no updates between the server and the client, it fails with local updater is 0.0.0.0 (no valid interface found).

With this error I checked the status of the trunk link ports and found they were down even though I had enabled them, I brought them back up again but a few seconds later they go back down again. I further discovered that this happens on all the ports even the VLAN1 interface.

I have defaulted the switches and tried with a very basic config but they are still going down.

I'm not sure if there is something I have missed or if it is the simulator but this has never happened to me before, any help would be appreciated.

[Aileron88]

Hi there,

Can you post the configuration of the trunk ports?

sh run int xx

Thanks

[jamesy_281]

Hi Adam,

Thanks for the quick reply, I have pasted the results of the show command on both ports.

Switch2 (VTP Client)

Building configuration...

Current configuration : 54 bytes
!
interface FastEthernet0/1
switchport mode trunk
end

Swicth1 (VTP Server)

Building configuration...

Current configuration : 55 bytes
!
interface FastEthernet0/10
switchport mode trunk
end

[network770]

can you add the dot1q encapsulation and see if that makes any difference.

I would also hard code the speed and duplex settings

[glen.grant]

  Does the vtp domain name match on each device ?   Also make sure the vtp version  matches on each side .

[jamesy_281]

OK so I built a new test lab with just two 2950 switches, I habe recreated the VTP setup, set the VTP version to 2 on both, set the port speed & duplex

and set the ip address on each VLAN1 interface. I also set the mode on all the other interfaces to access and shut them down.

The interfaces seem to be staying up now so I can only think something was wrong with the previous config, however I still cannot get vtp updates between the switches, I ave poeted the out put of the interfaces below.

Switch 1 (Server)

VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 64
Number of existing VLANs        : 6

VTP Operating Mode              : Server
VTP Domain Name                 : test.local
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0xEE 0xB3 0xDC 0x9F 0xE2 0xE0 0x25 0xDF
Configuration last modified by 0.0.0.0 at 3-1-93 04:55:57
Local updater ID is 0.0.0.0 (no valid interface found)

############################################

Name: Fa0/1
Switchport:     Enabled
Administrative mode: trunk
Operational mode: trunk
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001

Protected: false

Appliance trust: none

Switch 2 (Client)

VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 64
Number of existing VLANs        : 6

VTP Operating Mode              : Client
VTP Domain Name                 : test.local
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0xEE 0xB3 0xDC 0x9F 0xE2 0xE0 0x25 0xDF
Configuration last modified by 0.0.0.0 at 3-1-93 04:55:57
Local updater ID is 0.0.0.0 (no valid interface found)

################################################################

Name: Fa0/1
Switchport:     Enabled
Administrative mode: trunk
Operational mode: trunk
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001

Protected: false

Appliance trust: none

[johnlloyd_13]

Hi,

Just to cover the basics, did you use a crossover cable between the 2950s?

Sent from Cisco Technical Support iPhone App

[cadet alain]

Hi,

Just remove then add again a vlan on the vtp server switch and tell us what happens.

Regards.

Alain.

[jamesy_281]

OK, so it appears that vlan information is passing between the server and client switches, I was so fixated with the VTP error that I did not check the VLAN status on the client. when adding a new vlan to the server it appears instantly on the client.

Here's the strange thing VTP status still shows the previous error of no valid interface.... but it does show the number of vlans correctly however the config revision is still 0.

I can only suspect that this is strange behaviour on the simulator, but the bottom line is it's working.

Thanks for all the help guy's it's really appreciated, no doubt I will be back on my journey to becoming a CCNA.