VTP Version 3

Doing some further testing on whether VTP version is propogated as is the VTP domain name when all switches are configured with null values and a VTP Server is configured with a domain name. When configuring a VTP server with VTP domain name of CCIE and VTP version 2, this configuration propogates to all switches whether they are configured for client or server. However, when configuring VTP version 3, this configuration is not propogated to the rest of the switches in the VTP domain. I am currently utilizing Version 12.2(55)SE7 on my 3750Gs. The workbook specifically states "VTP version, just like VTP domain name, can be dynamically learned from VTP advertisements (if the VTP mode is client or server)." I understand the interoperability, however, should the client/server switches in the VTP domain change their version to VTP version 3 when the Server switch is configured for VTP Version 3?

Comments

  • the main point is that VTP Version 1 and VTP version 3 do not work together.. so if you have clients that only support version 1 and 2 and you use version 3 you have to manually change the remaining devices to vtp version 2 if you want to propagate vlan information via VTP to these devices. 

    possible that this is the reason why vtp version 1 to version 3 is also not working (missing TLV fields in version 1 maybe).

  • Hi,

       If you don't run VTP features that are supported only by VTPv2 or VTPv3, you can have a mixed environment without problems. VTP doman name is still learned from a VTPv3 device by both VTPv1 and VTPv2 devices. But because the VTP message format is different in VTPv3, the VTPv3 device will detect non VTPv3 devices and run in compatible mode out on those trunks; for this reason the VTP version is NOT learned, it needs to be manually configured on all devices.

    Regards,

    Cristian.

  • yes they VTP V1 and VTP V3 clients do exchange the domain name but no VLAN information. There is no compatible mode between

    V1 and V3. Since V1 does not support TLVs. I did a small lab:

     

    SW4#conf t

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

    SW4(config)#vtp vers 3

    Cannot set the version to 3 because domain name is not configured

    SW4(config)#vtp domain TST

    Changing VTP domain name from NULL to TST

    SW4(config)#vtp vers 3    

    %SW_VLAN-6-VTP_DOMAIN_NAME_CHG: VTP domain name changed to TST.

    SW4(config)#vtp vers 3

     

    Server replicated domain name to VTP v1 Server/ Client

     

    V1 Clients do not use the additional VTP informations received.

     

    debug sw-vlan vtp events shows:

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 0, followers = 1, length 77, trunk Fa0/21

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Summary packet rev 0 equal to domain TST2 rev 0

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Subset packet received, domain = TST2, rev = 0, seq = 1, length = 204

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 0, followers = 1, length 77, trunk Fa0/22

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Summary packet rev 0 equal to domain TST2 rev 0

     

    *Mar  1 00:07:50.064: VTP LOG RUNTIME: Subset packet received, domain = TST2, rev = 0, seq = 1, length = 204

     

    *Mar  1 00:08:02.563: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 0, followers = 1, length 77, trunk Fa0/19

     

    but no VLAN information added to VTP database.

     

    Changed VTP Version to 2 on the clients (Server still using V3)

     

    *Mar  1 00:09:04.370: VTP LOG RUNTIME: Transmit vtp summary, domain TST2, rev 1, followers 1, tlv blk size 8 (inc #tlv field),

       MD5 digest calculated = 6A C4 36 93 DA 2D 44 B1 E7 08 B5 73 AC B5 50 62

     

    *Mar  1 00:09:04.370: VTP LOG RUNTIME: Transmit vtp summary, domain TST2, rev 1, followers 1, tlv blk size 8 (inc #tlv field),

       MD5 digest calculated = 6A C4 36 93 DA 2D 44 B1 E7 08 B5 73 AC B5 50 62

     

    *Mar  1 00:09:04.370: VTP LOG RUNTIME: Transmit vtp summary, domain TST2, rev 1, followers 1, tlv blk size 8 (inc #tlv field),

       MD5 digest calculated = 6A C4 36 93 DA 2D 44 B1 E7 08 B5 73 AC B5 50 62

     

    *Mar  1 00:09:04.378: VTP LOG RUNTIME: Transmit vtp summary, domain TST2, rev 1, followers 1, tlv blk size 8 (inc #tlv field),

       MD5 digest calculated = 6A C4 36 93 DA 2D 44 B1 E7 08 B5 73 AC B5 50 62

     

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 1, followers = 1, length 80, trunk Fa0/19

     

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Summary packet rev 1 equal to domain TST2 rev 1

     

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Subset packet received, domain = TST2, rev = 1, seq = 1, length = 200

     

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 1, followers = 1, length 80, trunk Fa0/20

     

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4

    *Mar  1 00:09:04.395: VTP LOG RUNTIME: Summary packet rev 1 equal to domain TST2 rev 1

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Subset packet received, domain = TST2, rev = 1, seq = 1, length = 200

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 1, followers = 1, length 80, trunk Fa0/21

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Summary packet rev 1 equal to domain TST2 rev 1

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Subset packet received, domain = TST2, rev = 1, seq = 1, length = 200

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Summary packet received, domain = TST2, rev = 1, followers = 1, length 80, trunk Fa0/22

     

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Validate TLVs : #tlvs 1, max blk size 4

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Validate TLVs : #00, val 6, len 4

    *Mar  1 00:09:04.403: VTP LOG RUNTIME: Summary packet rev 1 equal to domain TST2 rev 1

     

    it adds the additional VLANS to the DB. It also starts validating the received TLVs.

     

    SW3(config)#do sh vl bri | ex unsu

     

    VLAN Name                             Status    Ports

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

    1    default                          active    Fa0/1, Fa0/2, 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, Fa0/23, Fa0/24

                                                    Gi0/1, Gi0/2

    10   VLAN0010                         active    

    30   VLAN0030                         active    

     

    Br

     

    Martin

  • and also according to the 3560 config Guide V1 and V2 do not work together:

     

    imageVTP version 1 and VTP version 2 are not interoperable on switches in the same VTP domain. Do not enable VTP version 2 unless every switch in the VTP domain supports version 2.

     

    http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560_scg/swvtp.html#wp1233873

     

    Br

     

    Martin

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