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3750 <--ISL--> 1912 problem

When port on 3750 is in access mode (vlan 24), and port on 1912 is trunk off, everything is ok. But now I need to communicate the devices via ISL trunk. I had configured both machines by the appropriate tech docs, but i have troubles...

On 1912 machine:

!

ip address 10.195.60.2 255.255.255.0

ip default-gateway 10.195.60.1

!

interface FastEthernet 0/26

duplex full

!

!

trunk On

!

On 3750 machine:

!

interface GigabitEthernet2/0/20

description Trunk to Cisco 1912

switchport encapsulation isl

switchport mode trunk

no mdix auto

!

!

interface Vlan24

ip address 10.195.60.1 255.255.255.0

!

In this way configuration (trunking), there is no ping between them.

May be i do something wron? PLS HELP!

1 ACCEPTED SOLUTION

Accepted Solutions
VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

you are right, your output shows that your 1912 os running VTP version 1, and your 3750 version 2. Make sure the versions are the same on both switches...

Regards,

GP

11 REPLIES
VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

can you check the VTP configuration of the 1912 ? AFAIR, the 1912 defaults to VTP server mode, so you either need to create the VLAN (24) on the 1912, or make the 3750 the VTP server and the 1912 the VTP client for the VTP domain...

Regards,

GP

New Member

Re: 3750 <--ISL--> 1912 problem

Thanks a lot but,

As you can saw above, Vlan is created on 3750, and 3750 is in server mode. 1912 is in client mode.

3750s#show vtp status

VTP Version : 2

Configuration Revision : 101

Maximum VLANs supported locally : 1005

Number of existing VLANs : 39

VTP Operating Mode : Server

VTP Domain Name : Meri

VTP Pruning Mode : Disabled

VTP V2 Mode : Disabled

VTP Traps Generation : Enabled

MD5 digest : 0xFA 0x50 0xEE 0xB1 0x16 0x83 0x30 0x34

Configuration last modified by 10.195.0.1 at 11-8-05 08:15:11

Local updater ID is 10.195.0.1 on interface Vl1 (lowest numbered VLAN interface found)

Catalyst_1912#show vtp

VTP version: 1

Configuration revision: 1

Maximum VLANs supported locally: 1005

Number of existing VLANs: 5

VTP domain name : meri

VTP password : password

VTP operating mode : Client

VTP pruning mode : Disabled

VTP traps generation : Enabled

Configuration last modified by: 10.195.60.2 at 00-00-0000 00:00:00

May be configuration of VTP is wrong somewhere?

VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

VTP domain names are case-sensitive, it looks like you have ´Meri´ (with a capital M) configured on your 3750, and ´meri´ (small caps m) on your 1912, make sure the names match...

Regards,

GP

New Member

Re: 3750 <--ISL--> 1912 problem

Hm... now i had configured `Meri` on both devices. But still the same problem. May be trouble in the difference of VTP versions?

Statistics:

3750s#show vtp counters

VTP statistics:

Summary advertisements received : 0

Subset advertisements received : 0

Request advertisements received : 46507

Summary advertisements transmitted : 147343

Subset advertisements transmitted : 46516

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

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

Gi1/0/1 0 0 0

Gi1/0/2 0 0 0

Gi1/0/4 0 0 0

Gi1/0/8 0 0 0

Gi1/0/12 0 0 0

Gi2/0/5 0 0 0

Gi2/0/8 0 0 0

Gi2/0/15 0 0 0

Gi2/0/19 0 0 0

Gi2/0/20 0 0 0

Catalyst_1912#show vtp statistics

Receive Statistics Transmit Statistics

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

Summary Adverts 4 Summary Adverts 5

Subset Adverts 0 Subset Adverts 4

Advert Requests 0 Advert Requests 50

Configuration Errors:

Revision Errors 0

Digest Errors 0

VTP Pruning Statistics:

Port Join Received Join Transmitted Summary Adverts received

with no pruning support

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

A 0 0 0

B 0 0 0

New Member

Re: 3750 <--ISL--> 1912 problem

You are trying to connect Gigaethernet to fastethernet. Is gigaethernet capable of negotiating speed ? Check this. Are you able to ping the switch 1900 from 3750 and vice versa?

VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

you are right, your output shows that your 1912 os running VTP version 1, and your 3750 version 2. Make sure the versions are the same on both switches...

Regards,

GP

New Member

Re: 3750 <--ISL--> 1912 problem

Does 1912 suports VTP version 2.0 I can't find it in the command line, and i can not change vtp version on the 3750 because this is the main VTP server of our domain and probably i think it may cause fault of communications to other switches, whic are working via VTP 2

VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

that is going to be problematic, since 1900 (and 2820) switches only support VTP version 1...

Regards,

GP

New Member

Re: 3750 <--ISL--> 1912 problem

Ok. How to decrease VTP from 2.0 to 1.0 version on 3750?

Re: 3750 <--ISL--> 1912 problem

Hi..

On 3750

conf t

vtp version 1

You are done.

regards,

-amit singh

VIP Purple

Re: 3750 <--ISL--> 1912 problem

Hello,

watch out though with changing the VTP version: version 1 and 2 are not interoperable. You will loose all connectivity between switches running a different VTP version. It might be a good idea to do this afterhours...:)

Regards,

GP

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