vtp v3 and vtp v2 interoperability

[bbb bbb]

hi,

.

.

Would like to confirm regarding VTP version 3 and VTP version 2 interoperability, if the created vlan in a switch running vtp version 3 will be dynamically learned by a switch running vtp version 2?

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i am trying to lab these:

..

SW1=acting as vtp version 3 server for vlan and mst feature

            created vlan 1-10;

            configured MST instance 1 vlan 1-5

            configured MST instance 2 vlan 6-10

            created vlan 11-20

..

SW2=acting as a vtp version 2 client (vtp v1-2 only); 

            vlan 1-10 at SW1 not learned

            vlan 11-20 at SW1 not learned

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SW1<>SW2 connected via trunk

noted that MST configurations from SW1 will not be dynamically learned by SW2. 

.

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thanks,

bbb

[Peter Paluch · Accepted solution]

Hi bbb,

To add to Inayath's answer, while VTPv3 is capable of propagating MST region configuration to all switches within a VTP domain (hence the domain will become a single MST region), there is no such capability in VTPv2. VTPv2 can only advertise VLANs, and is incapable of carrying any other information such as MST region configuration.

VTPv3 is backwards compatible only with VTPv2. It will not cooperate with VTPv1-enabled switches.

VLANs created on a VTPv3 switch will propagate to a VTPv2 switch if these switches are interconnected by a trunk link, are placed into the same VTP domain and use the same VTP password (if configured). For security reasons, this process does not work in the opposite way: Any change to the VLAN database performed on a VTPv2 switch will not propagate to the VTPv3 switch - it will ignore the advertisement.

Best regards,
Peter

[InayathUlla Sharieff · Accepted solution]

Provide us VTP configuration between the SW1 and SW2. Also share the following outputs:-

SW1# show vlan brief

SW1#show vtp status ( also from SW2--make sure the md5 value is same).

SW1#show int trunk

SW1#sh run int <x/x>-- trunk link interface.

HTH

REgards

Inayath

[bbb bbb]

Hello,

here is the setup.. SW1--<2xtrunk links>--SW2.. both are running in rstp

summary of config

SW1=running vtp version 3; vtp domain=cisco,vtp server mode;no vtp password;L2 switch;C2960G; C2960-LANBASEK9-M 15.0(2)SE6

SW2=running vtp version 2;vtp domain=cisco, vtp client mode; no vtp password;L3/L2 switch;ip routing disabled;C3550; C3550-IPSERVICESK9-M 12.2(44)SE6

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here are the configurations for this setup

@SW1

SW1#sh vlan br

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Gi0/3, Gi0/4, Gi0/10, Gi0/43
Gi0/44, Gi0/45, Gi0/46, Gi0/47
Gi0/48
30 VLAN0030 active
31 VLAN0031 active
32 VLAN0032 active
33 VLAN0033 active
34 VLAN0034 active
35 VLAN0035 active
1002 fddi-default act/unsup
1003 trcrf-default act/unsup
1004 fddinet-default act/unsup
1005 trbrf-default act/unsup

SW1#show vtp status
VTP Version capable : 1 to 3
VTP version running : 3
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP Traps Generation : Disabled
Device ID : 0022.0d4a.b280

Feature VLAN:
--------------
VTP Operating Mode : Primary Server
Number of existing VLANs : 11
Number of existing extended VLANs : 0
Maximum VLANs supported locally : 255
Configuration Revision : 4
Primary ID : 0022.0d4a.b280
Primary Description : SW1
MD5 digest : 0xBC 0xE2 0x61 0x02 0x82 0x25 0xB5 0x2F
0xDB 0xB3 0x0B 0x17 0x2C 0xD4 0xC6 0x14

Feature MST:
--------------
VTP Operating Mode : Transparent

Feature UNKNOWN:
--------------
VTP Operating Mode : Transparent

SW1#show interface trunk

Port Mode Encapsulation Status Native vlan
Gi0/1 on 802.1q trunking 1
Gi0/2 on 802.1q trunking 1

Port Vlans allowed on trunk
Gi0/1 1-4094
Gi0/2 1-4094

Port Vlans allowed and active in management domain
Gi0/1 1,30-35
Gi0/2 1,30-35

Port Vlans in spanning tree forwarding state and not pruned
Gi0/1 1,30-35
Gi0/2 30-35
SW1# sh run int g0/1
Building configuration...

Current configuration : 59 bytes
!
interface GigabitEthernet0/1
switchport mode trunk
end

SW1# sh run int g0/2
Building configuration...

Current configuration : 59 bytes
!
interface GigabitEthernet0/2
switchport mode trunk
end

SW1#

@SW2

SW2#show vlan br

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6
Fa0/7, Fa0/8, Fa0/9, Fa0/10
Fa0/11, Fa0/12, Fa0/13, Fa0/14
Fa0/15, Fa0/16, Fa0/17, Fa0/18
Fa0/19, Fa0/20, Fa0/21, Fa0/22
Fa0/23, Fa0/24, Gi0/1, Gi0/2
1002 fddi-default act/unsup
1003 trcrf-default act/unsup
1004 fddinet-default act/unsup
1005 trbrf-default act/unsup
SW2#show vtp status
VTP Version : running VTP2
Configuration Revision : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs : 5
VTP Operating Mode : Client
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Enabled
VTP Traps Generation : Disabled
MD5 digest : 0x6A 0x12 0xF0 0x1F 0x35 0x2A 0x8C 0xBD
Configuration last modified by 0.0.0.0 at 3-1-93 00:42:44
SW2#sh interface trunk

Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Fa0/2 on 802.1q trunking 1

Port Vlans allowed on trunk
Fa0/1 1-4094
Fa0/2 1-4094

Port Vlans allowed and active in management domain
Fa0/1 1
Fa0/2 1

Port Vlans in spanning tree forwarding state and not pruned
Fa0/1 1
Fa0/2 1
SW2#sh run int f0/1
Building configuration...

Current configuration : 94 bytes
!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
end

SW2#sh run int f0/2
Building configuration...

Current configuration : 94 bytes
!
interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk
end

SW2#

@Peter Paluch

thanks for the explanation.that is the reason why this scenario is made. 

im actually trying out mst configuration, there is another switch SW3 (same device model of SW1)

and it worked fine. but when i just want to propagate only vlans (STP in rstp mode)SW2 is not dynamically learning the vlans, while SW3 works just fine.

@InayathUlla Sharieff

is it possible that SW2 has ios issue?

[bbb bbb]

Hello,

the switches i used previously deployed in a production network whereas they have learned their vlans through previous vtp server.

when i put them on this setup, didnt mind of putting the switches on a clean config by deleting the vlan.dat and config.text from the flash. it was only deleting old vlans, and reconfiguring the vtp mode from client to server, and changing the vtp domain.

after putting them on a clear config and doing again the setup finally made SW2 dynamically learned the vlans defined at SW1. finally saw the vtp advertisments.

thank you and regards,