Chapter 3: VTP Configuration Part One (Preview)

You must first complete Chapter 3: VLAN Trunking Protocol Walk-through Part One before viewing this Lesson

Let’s examine how to setup VTP. In our topology below, we have already setup trunk links between SW1 and SW3, also between SW2 and SW3. Now let’s setup VTP in such a way that, If I were to add a new VLAN on SW1 then that VLAN will be advertised over all the trunk links to SW2 and SW3 and that the newly created VLAN will be learned by other switches. Also, for this example I am using Cisco Catalyst 3750 switches and all of them are running the identical Cisco IOS.

 

 

Figure Network diagram consisting of three Cisco Catalyst 3750 switches connected through trunk links
As shown in the network diagram let’s configure SW1 and SW3 in VTP Server mode while we configure SW2 in client mode.

Before we start our configuration let’s look at how the out of the box configuration looks like.

SW1#show vlan brief

 

VLAN Name                             Status    Ports

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

1    default                          active    Fa1/0/2, Fa1/0/3, Fa1/0/4, Fa1/0/5, Fa1/0/6, Fa1/0/7, Fa1/0/8, Fa1/0/9, Fa1/0/10, Fa1/0/11

                                                Fa1/0/12, Fa1/0/13, Fa1/0/14, Fa1/0/15, Fa1/0/16, Fa1/0/17, Fa1/0/18, Fa1/0/19, Fa1/0/20

                                                Fa1/0/21, Fa1/0/22, Fa1/0/23, Fa1/0/24, Gi1/0/1, Gi1/0/2

1002 fddi-default                     act/unsup

1003 token-ring-default               act/unsup

1004 fddinet-default                  act/unsup

1005 trnet-default                    act/unsup

 

SW1#show vtp status

VTP Version capable             : 1 to 3

VTP version running             : 1

VTP Domain Name                 :

VTP Pruning Mode                : Disabled

VTP Traps Generation            : Disabled

Device ID                       : 001c.0f20.b300

Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

Local updater ID is 192.168.1.81 on interface Vl1 (lowest numbered VLAN interface found)

 

Feature VLAN:

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

VTP Operating Mode                : Server

Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5

Configuration Revision            : 0

MD5 digest                        : 0x57 0xCD 0x40 0x65 0x63 0x59 0x47 0xBD 
                                    0x56 0x9D 0x4A 0x3E 0xA5 0x69 0x35 0xBC 

Example SW1 pre-change configuration

SW2#show vlan brief

 

VLAN Name                             Status    Ports

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

1    default                          active    Fa1/0/2, Fa1/0/3, Fa1/0/4, Fa1/0/5, Fa1/0/6, Fa1/0/7, Fa1/0/8, Fa1/0/9, Fa1/0/10, Fa1/0/11

                                                Fa1/0/12, Fa1/0/13, Fa1/0/14, Fa1/0/15, Fa1/0/16, Fa1/0/17, Fa1/0/18, Fa1/0/19, Fa1/0/20

                                                Fa1/0/21, Fa1/0/22, Fa1/0/23, Fa1/0/24, Gi1/0/1, Gi1/0/2

1002 fddi-default                     act/unsup

1003 token-ring-default               act/unsup

1004 fddinet-default                  act/unsup

1005 trnet-default                    act/unsup

SW2#show vtp status

VTP Version capable             : 1 to 3

VTP version running             : 1

VTP Domain Name                 :

VTP Pruning Mode                : Disabled

VTP Traps Generation            : Disabled

Device ID                       : 001a.e3a7.7600

Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

Local updater ID is 192.168.1.82 on interface Vl1 (lowest numbered VLAN interface found)

 

Feature VLAN:

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

VTP Operating Mode                : Server

Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5

Configuration Revision            : 0

MD5 digest                        : 0x57 0xCD 0x40 0x65 0x63 0x59 0x47 0xBD

0x56 0x9D 0x4A 0x3E 0xA5 0x69 0x35 0xBC

Example SW2 pre-change configuration

SW3#show vlan brief

 

VLAN Name                             Status    Ports

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

1    default                          active    Fa1/0/1, Fa1/0/3, Fa1/0/4, Fa1/0/5, Fa1/0/6, Fa1/0/7, Fa1/0/8, Fa1/0/9, Fa1/0/10, Fa1/0/11

                                                Fa1/0/13, Fa1/0/14, Fa1/0/15, Fa1/0/16, Fa1/0/17, Fa1/0/18, Fa1/0/19, Fa1/0/20, Fa1/0/21

                                                Fa1/0/22, Fa1/0/23, Fa1/0/24, Gi1/0/1, Gi1/0/2

1002 fddi-default                     act/unsup

1003 token-ring-default               act/unsup

1004 fddinet-default                  act/unsup

1005 trnet-default                    act/unsup

SW3#show vtp status

VTP Version capable             : 1 to 3

VTP version running             : 1

VTP Domain Name                 :

VTP Pruning Mode                : Disabled

VTP Traps Generation            : Disabled

Device ID                       : 001a.e3a7.f080

Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00

Local updater ID is 192.168.1.83 on interface Vl1 (lowest numbered VLAN interface found)

 

Feature VLAN:

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

VTP Operating Mode                : Server

Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5

Configuration Revision            : 0

MD5 digest                        : 0x57 0xCD 0x40 0x65 0x63 0x59 0x47 0xBD 
                                    0x56 0x9D 0x4A 0x3E 0xA5 0x69 0x35 0xBC 

Example SW3 pre-change configuration

Firstly, lets configure SW1 with the VTP parameters as shown in the diagram.

Secondly, let’s configure SW3 with an identical configuration.

Finally, configure the SW2. Only difference here is that we are going to configure SW2 as a VTP Client.

SW1#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

SW1(config)#vtp ?
!--- Examining the available vtp configuration parameters ---!
domain     Set the name of the VTP administrative domain.

file       Configure IFS filesystem file where VTP configuration is stored.

interface  Configure interface as the preferred source for the VTP IP updater address.

mode       Configure VTP device mode

password   Set the password for the VTP administrative domain

pruning    Set the administrative domain to permit pruning

version    Set the administrative domain to VTP version

 

SW1(config)#vtp domain PACKET_LAB
!--- Setting VTP domain name to PAKET_LAB ---!
Changing VTP domain name from NULL to PACKET_LAB

SW1(config)#vtp mode server
!--- Setting device to VTP Server mode for VLANS ---!
Device mode already VTP Server for VLANS.

SW1(config)#vtp password c!sco
!--- Setting device VLAN database password to c!sco ---!
Setting device VTP password to c!sco

SW1(config)#vtp version ?

<1-3>  Set the administrative domain VTP version number 

SW1(config)#vtp version 2
!--- Setting VTP version to version 2 ---!
SW1(config)#vtp pruning
!--- Enabling VTP pruning ---!
Pruning switched on

SW1(config)#^Z

SW1#show vtp status
!--- Examinig the current VTP configuration on SW1 ---!
VTP Version capable             : 1 to 3
!--- What the above line tells us is that the switch is capable of running VTP version 1,2 or 3 ---!
VTP version running             : 2
!--- Current running VTP version is 2 ---!
VTP Domain Name                 : PACKET_LAB
!--- VTP domain name is PACKET_LAB ---!
VTP Pruning Mode                : Enabled
!--- VTP pruning is enabled ---!
VTP Traps Generation            : Disabled

Device ID                       : 001c.0f20.b300

Configuration last modified by 192.168.1.81 at 3-1-93 00:41:48

Local updater ID is 192.168.1.81 on interface Vl1 (lowest numbered VLAN interface found)

 

Feature VLAN:

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

VTP Operating Mode                : Server
!--- Current VTP mode is Server ---!
Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5
!--- There are 5 VLANs in the VLAN Database ---!
Configuration Revision            : 2
!--- Current configuration revision number is 2 ---!
MD5 digest                        : 0x34 0x49 0xBA 0x0E 0x6E 0xCD 0x57 0x99 
                                    0xEF 0x6D 0xC2 0x46 0xF8 0xFE 0xAA 0x58 
!--- This is the MD5 Hash that was created to represent the password c!sco ---!
SW1#wr

Building configuration...

[OK]

Example VTP Configuration on SW1

SW3#

SW3#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

SW3(config)#vtp domain PACKET_LAB

Domain name already set to PACKET_LAB.

SW3(config)#vtp mode server

Device mode already VTP Server for VLANS.

SW3(config)#vtp password c!sco

Setting device VTP password to c!sco

SW3(config)#vtp pruning

Pruning switched on

SW3(config)#vtp version 2

VTP version is already in V2.

SW3(config)#^Z

SW3#wr

Building configuration...

[OK]



SW3#show vtp status

VTP Version capable             : 1 to 3

VTP version running             : 2

VTP Domain Name                 : PACKET_LAB

VTP Pruning Mode                : Enabled

VTP Traps Generation            : Disabled

Device ID                       : 001a.e3a7.f080

Configuration last modified by 192.168.1.81 at 3-1-93 00:41:48

Local updater ID is 192.168.1.83 on interface Vl1 (lowest numbered VLAN interface found)

 

Feature VLAN:

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

VTP Operating Mode                : Server

Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5

Configuration Revision            : 2

MD5 digest                        : 0x34 0x49 0xBA 0x0E 0x6E 0xCD 0x57 0x99 
                                    0xEF 0x6D 0xC2 0x46 0xF8 0xFE 0xAA 0x58 

Example VTP Configuration on SW3

 

We can see our configuration settings are identical to SW1 and that the VTP has converged between SW1 and SW3.

SW2#configure terminal

Enter configuration commands, one per line.  End with CNTL/Z.

SW2(config)#vtp domain PACKET_LAB

Domain name already set to PACKET_LAB.
!--- SW2 has already learned the domain name via the VTP messages from other switches ---!
SW2(config)#vtp mode client

Setting device to VTP Client mode for VLANS.

SW2(config)#vtp password c!sco

Password already set to c!sco

SW2(config)#vtp version 2

Cannot modify version in VTP client mode unless the system is in VTP version 3
!--- Since this is a VTP Client mode switch we are not allowed to change this setting. These settings are already learned through VTP Server mode switches ---!
SW2(config)#vtp pruning

Cannot modify pruning unless in VTP server mode
!--- Since this is a VTP Client mode switch we are not allowed to change this setting. These settings are already learned through VTP Server mode switches ---!
SW2(config)#^Z

SW2#wr

Building configuration...

[OK]

SW2#show vtp status

VTP Version capable             : 1 to 3

VTP version running             : 2

VTP Domain Name                 : PACKET_LAB

VTP Pruning Mode                : Enabled

VTP Traps Generation            : Disabled

Device ID                       : 001a.e3a7.7600

Configuration last modified by 192.168.1.81 at 3-1-93 00:41:48

 

Feature VLAN:

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

VTP Operating Mode                : Client

Maximum VLANs supported locally   : 1005

Number of existing VLANs          : 5

Configuration Revision            : 2

MD5 digest                        : 0x34 0x49 0xBA 0x0E 0x6E 0xCD 0x57 0x99 
                                    0xEF 0x6D 0xC2 0x46 0xF8 0xFE 0xAA 0x58 

Example VTP Configuration on SW2

Looking at the show vtp status of all three switches we can see that VTP seem to have converged on all three switches.

In our next lesson let’s do some modifications to the VLAN database and examine if VTP works as it should.

Lesson tags: VTP
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