VTP server-client between 2x 3550 EMI

[cchiu6cfcl]

I have 2x 3550 EMI switches connected via a dedicated 10Mb circuit and they are physically located in difference places.

The 3550 in my office is configured as VTP server and the remote 3550 is configured as VTP client.

However, VTP information is propagated from server to client even though "sh vtp status" indicates the remote 3550 is indeed in client mode with correct domain and password.

Also "sh vtp counters" results has all zero in every statistics.

The remote 3550 was originally configured as server as well, but I want to synchronise vlan database on these two 3550, so made the remote one a client.

Any suggestions as why thie VTP server-client does not work?

Chiu.

[mahmoodmkl]

Hi

Can u configure the link between them as trunk port and see that u have the same encapsulation at both the ends.

Thanks

Mahmood

[cchiu6cfcl]

Mahmood,

The 3550 interfaces on both side of the 10Mb circuit are configured as trunk with dot1q encap.

The VLAN traffic "seems" to propagate over the link alright as I have not noticed any problems "yet".

The whole problem is actually more complicated but I need to get this VTP issue sorted out first to make sure both 3550 communicate properly.

I have configured another 3560 as a client to our office 3550 and it went without any issues. All VLAN database gets propagated from 3550 to 3560 like normal.

Only this remote 3550 is not behaving as expected. BTW, we only have these 3 switches where 1x 3550 and 1x 3560 are local and 1x 3550 is remote.

Any debuging options can help find out where the problem actually is? Some debug output just confuses me more than providing useful info, like "debug spanning-tree bpdu" command.

Chiu.

[ohassairi]

try

debug sw-vlan vtp packets

and let us know.

[Amit Singh]

Chiu,

Please paste the switch configurations.I agree with mehmood on this to check the ports as trunl with encapsulation.

Please paste the output of "show interface x/y switchport" from both the switch interfaces which are connected to both sites.

-amit singh

[Amit Singh]

Chiu,

What exactly is the problem that your facing? Arn't the Vlans propogating to the remote 3550?

Try creating a dummy vlan on 3550 at the central site and check if that is updated on 3550 remote.If its is OK, then your things are working as expected.If not, we have some problem.

To diagnose it we would require the output of "show VTP status", " show VTP counters" and running config of both the switches.

HTH,

-amit singh

[cchiu6cfcl]

Amit,

The problem is VTP propagation between 3550s and normal traffic seems alright.

The remote 3550 just wouldn't synchronise with central 3550 when it's in client mode.

The show VTP status on remote 3550 indicates it's in client mode and domain/password have been set correctly. However, the vlan database and revision number are not the same as central 3550.

The show VTP counters on remote 3550 indicates zero advertisements received or transmitted and zero errors. In fact, all statistical numbers in the command output are zero.

As far as I know, running-config on both 3550s appears to be the similar except some minor difference such as spanning tree priority....

I'll provide some running-config here a bit later for your reference.

Chiu.

[Amit Singh]

Chiu,

What happens when you try creating a dummy vlan at the central site? Do you see it at the remote ?

Please paste the output from "show VTP counters " and "Show VTP status" from both the switches.Also the running config.

-amit singh

[cchiu6cfcl]

Amit,

Nope, it does not appear at the remote.

Central 3550:

sh vtp status

VTP Version : 2

Configuration Revision : 27

Maximum VLANs supported locally : 1005

Number of existing VLANs : 12

VTP Operating Mode : Server

VTP Domain Name : IDCAP

VTP Pruning Mode : Disabled

VTP V2 Mode : Enabled

VTP Traps Generation : Disabled

MD5 digest : 0x5A 0xF2 0xB3 0x23 0x1A 0x8D 0xC3 0x6D

Configuration last modified by 172.24.61.252 at 1-17-07 13:40:57

Local updater ID is 172.24.61.252 on interface Vl1 (lowest numbered VLAN interface found)

sh vtp counters

VTP statistics:

Summary advertisements received : 1

Subset advertisements received : 1

Request advertisements received : 0

Summary advertisements transmitted : 9

Subset advertisements transmitted : 3

Request advertisements transmitted : 0

Number of config revision errors : 0

Number of config digest errors : 0

Number of V1 summary errors : 0

VTP pruning statistics:

Trunk Join Transmitted Join Received Summary advts received from

non-pruning-capable device

---------------- ---------------- ---------------- ---------------------------

Fa0/1 0 0 0

Fa0/47 0 0 0

Gi0/1 0 0 0

Remote 3550:

sh vtp status

VTP Version : 2

Configuration Revision : 4

Maximum VLANs supported locally : 1005

Number of existing VLANs : 9

VTP Operating Mode : Client

VTP Domain Name : IDCAP

VTP Pruning Mode : Disabled

VTP V2 Mode : Enabled

VTP Traps Generation : Disabled

MD5 digest : 0x39 0x8E 0xB3 0x3D 0xBF 0xAF 0xA0 0xF3

Configuration last modified by 172.24.61.251 at 1-17-07 06:51:18

sh vtp counters

VTP statistics:

Summary advertisements received : 0

Subset advertisements received : 0

Request advertisements received : 0

Summary advertisements transmitted : 2

Subset advertisements transmitted : 0

Request advertisements transmitted : 0

Number of config revision errors : 0

Number of config digest errors : 0

Number of V1 summary errors : 0

VTP pruning statistics:

Trunk Join Transmitted Join Received Summary advts received from

non-pruning-capable device

---------------- ---------------- ---------------- ---------------------------

Fa0/17 0 0 0

Fa0/23 0 0 0

F0/47 on cenral 3550 connects F0/23 on remote 3550 via 10Mb circuit.

Chiu.

[glen.grant]

Try putting in the vtp domain name again on the client side , its possible maybe someone introduced a space at the end of the name which would then make a mismtach of the vtp domain name, make sure no spaces after the name.

[cchiu6cfcl]

Grant,

I've done that a few times already, the result is "Domain name already set to IDCAP".

The strange thing is why remote 3550 never receive any kind of advertisements (summary, subnet, request), according to the show VTP counters output??

sh vtp counters

VTP statistics:

Summary advertisements received : 0

Subset advertisements received : 0

Request advertisements received : 0

Summary advertisements transmitted : 184

Subset advertisements transmitted : 0

Request advertisements transmitted : 0

Number of config revision errors : 0

Number of config digest errors : 0

Number of V1 summary errors : 0

Chiu.

[glen.grant]

Guess my last question would be is it actually trunking between those 2 interfaces , if its not actually trunking you won't get advertisements . Your best bet might be to post the full configs of the switches . If you do a "show int trunk " on both sides does the trunk look ok ? I would start checking to see if you can pings devices from both sides , if the trunk is working correctly then you should be able to ping from one side to the other .

[cchiu6cfcl]

Glen and all,

Sorry, got to leave for a while.....

All VLANs can talk each other without problem ... We also have routing enable for all VLANs.

Both interfaces have been configured as trunk but I just don't know why this happens....

I'll post the config here later, thanks.

Chiu.

[cchiu6cfcl]

Glen, Amit, Mahmood,

Here are the config files for central and remote 3550.

I couldn't find problems in the config, so please recommend any debug or show commands to help troubleshooting.

Chiu.

[Amit Singh]

Hi Chiu,

Just checked the config and nothing seems to be unusal.Config is OK.

Please let me know the IOS that you are running on both the 3550's i.e at central and remote.

-amit singh