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Frequent Contributor

VTP Pruning test

Hi Everyone,

I was testing the VTP Pruning on cisco switches.

Switch A is VTP server mode and is connected to Switch B  ---B  is client.

Switch A is connected to Switch C. ---C is Client mode.

I configured layer 3 interface vlan 2 on Switch A.

All other switches show vlan 2 now .

No ports on all 3 switches are assigned to Vlan 2.

I enabled VTP pruning on server and now all client switches shows that VTP pruning is enabled.

Switch A

shows

A#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Fa0/12      desirable        n-802.1q       trunking      1

Po10        on               802.1q         trunking      1

Port        Vlans allowed on trunk

Fa0/12      1-4094

Po10        1,10,20,30

Port        Vlans allowed and active in management domain

Fa0/12      1-2,10,20,30

Po10        1,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/12      1,20

Po10        1,10,20,30

This is correct behaviour as vlan 2 is pruned now.

B  shows

I

B#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Po10        on               802.1q         trunking      1

Port        Vlans allowed on trunk

Po10        1,10,20,30

Port        Vlans allowed and active in management domain

Po10        1,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Po10        1,10,20,30

This also seems ok

Switch C shows

sh int trunk

Port        Mode         Encapsulation  Status        Native vlan

Fa0/12      desirable    802.1q         trunking      1

Port      Vlans allowed on trunk

Fa0/12      1-4094

Port        Vlans allowed and active in management domain

Fa0/12      1-2,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/12      1-2,10,20,30

My question is why switch C  shows vlan 2 as not pruned.

Switch c has only switch A  as its nei.

Thanks


Everyone's tags (4)
1 ACCEPTED SOLUTION

Accepted Solutions
Highlighted
VIP Expert

VTP Pruning test

Yes, if switch A is the VTP server, than you need to configure it there, so switch A can replicate it to switch B and C.

Also, for testing and learning, this is fine.  If this is for production and you only have 3 switches with handful vlans, VTP doesn't do much for you.  Some times VTP causes more issues than helping you.

HTH

Reza

View solution in original post

9 REPLIES 9
Highlighted
VIP Expert

VTP Pruning test

Hi Mahesh,

Switch-B does not show vlan 2 at all.

Can you post your configs?

HTH

Reza

Highlighted
Frequent Contributor

VTP Pruning test

Hi Reza,

Thanks for reply.

I have attached run config of all 3 switches under first post.

Mahesh

Highlighted
VIP Expert

VTP Pruning test

Hi Mahesh,

Sorry, I didn't see the attachments.  Looking at switch-A config, I don't see any vtp config like vtp name, vtp mode, etc...

can you clarify?

Thanks,

Reza

Highlighted
Frequent Contributor

VTP Pruning test

Hi Reza,

Here is info from 3 switches

Switch B

B#sh vtp sta

3550SMIB#sh vtp status

VTP Version                     : running VTP2

Configuration Revision          : 48

Maximum VLANs supported locally : 1005

Number of existing VLANs        : 9

VTP Operating Mode              : Client

VTP Domain Name                 : manveer.com

VTP Pruning Mode                : Enabled

VTP V2 Mode                     : Enabled

VTP Traps Generation            : Disabled

MD5 digest                      : 0x8E 0xB5 0x29 0x8B 0x11 0x17 0xC3 0x11

Configuration last modified by 2.0.0.1 at 9-9-12 16:49:09

B#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Po10        on               802.1q         trunking      1

Port        Vlans allowed on trunk

Po10        1,10,20,30

Port        Vlans allowed and active in management domain

Po10        1,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Po10        1,10,20,30

A#sh vtp status

VTP Version                     : running VTP2

Configuration Revision          : 48

Maximum VLANs supported locally : 1005

Number of existing VLANs        : 9

VTP Operating Mode              : Server

VTP Domain Name                 : manveer.com

VTP Pruning Mode                : Enabled

VTP V2 Mode                     : Enabled

VTP Traps Generation            : Disabled

MD5 digest                      : 0x8E 0xB5 0x29 0x8B 0x11 0x17 0xC3 0x11

Configuration last modified by 2.0.0.1 at 9-9-12 16:49:09

Local updater ID is 2.0.0.1 on interface Vl2 (lowest numbered VLAN interface fou

nd)

A#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan

Fa0/12      desirable        n-802.1q       trunking      1

Po10        on               802.1q         trunking      1

Port        Vlans allowed on trunk

Fa0/12      1-4094

Po10        1,10,20,30

Port        Vlans allowed and active in management domain

Fa0/12      1-2,10,20,30

Po10        1,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/12      1,20

Po10        1,10,20,30

C#sh vtp status

VTP Version                     : 2

Configuration Revision          : 48

Maximum VLANs supported locally : 250

Number of existing VLANs        : 9

VTP Operating Mode              : Client

VTP Domain Name                 : manveer.com

VTP Pruning Mode                : Enabled

VTP V2 Mode                     : Enabled

VTP Traps Generation            : Disabled

MD5 digest                      : 0x8E 0xB5 0x29 0x8B 0x11 0x17 0xC3 0x11

Configuration last modified by 2.0.0.1 at 9-9-12 16:49:09

C# sh int trunk

Port        Mode         Encapsulation  Status        Native vlan

Fa0/12      desirable    802.1q         trunking      1

Port      Vlans allowed on trunk

Fa0/12      1-4094

Port        Vlans allowed and active in management domain

Fa0/12      1-2,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/12      1-2,10,20,30

HEre is config  u requested.Also under original posts at the bottom there is 3 attachments with all sh run config.

Thanks

MAhesh

Highlighted
VIP Expert

VTP Pruning test

Hi Mahesh,

Switch-A is the vtp server, but I don't see vlan 2 under portchannel 10.  Can you add it and try again?

interface Port-channel10

switchport trunk encapsulation dot1q

--More--                            switchport trunk allowed vlan 1,10,20,30

switchport mode trunk

speed nonegotiate

HTH

Reza

Highlighted
Frequent Contributor

VTP Pruning test

Hi Reza,

Thanks for reply.

Should i config that on switch A  only?

MAhesh

Highlighted
VIP Expert

VTP Pruning test

Yes, if switch A is the VTP server, than you need to configure it there, so switch A can replicate it to switch B and C.

Also, for testing and learning, this is fine.  If this is for production and you only have 3 switches with handful vlans, VTP doesn't do much for you.  Some times VTP causes more issues than helping you.

HTH

Reza

View solution in original post

Highlighted
Frequent Contributor

VTP Pruning test

Hi Reza,

Thanks for all the replies.

I was doing this for learning purposes.

regards

Mahesh

Highlighted
Frequent Contributor

VTP Pruning test

Hi Reza,

I did as you said on last post on Switch A  and B.

Switch C  still shows

C#sh int trunk

Port        Mode         Encapsulation  Status        Native vlan

Fa0/12      desirable    802.1q         trunking      1

Port      Vlans allowed on trunk

Fa0/12      1-4094

Port        Vlans allowed and active in management domain

Fa0/12      1-2,10,20,30

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/12      1-2,10,20,30

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