From: Guyler, Rik (rguyler@shp-dayton.org)
Date: Wed Mar 15 2006 - 10:51:13 GMT-3
VLAN information gets stored in the vlan.dat file. It gets created whenever
non-default VLANs are created on the device regardless of whether or not it
is via VTP or manual configuration.
Number two is sadly true. I read this in some obscure doc a couple of years
ago and was skeptical about it's accuracy so I labbed it up. Here is what I
just did for you on my 3550 pair (I removed some of the extra stuff we don't
need):
SW2(config)#do sh vtp st
VTP Version : 2
Configuration Revision : 6
Maximum VLANs supported locally : 1005
Number of existing VLANs : 9
VTP Operating Mode : Client
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x95 0x2F 0xA2 0xC3 0x98 0x98 0x6E 0xFE
Configuration last modified by 0.0.0.0 at 3-2-93 21:17:22
SW2(config)#do sh vlan
VLAN Name Status Ports
---- -------------------------------- --------- ---------
1 default active
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
40 VLAN0040 active
***************************************************************
SW1#sh vlan
VLAN Name Status Ports
---- -------------------------------- --------- ----------
1 default active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
SW1#sh vtp st
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs : 5
VTP Operating Mode : Transparent
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x57 0x30 0x6D 0x7A 0x76 0x12 0x7B 0x40
Configuration last modified by 0.0.0.0 at 3-2-93 21:14:23
SW1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
SW1(config)#vtp mod ser
Setting device to VTP SERVER mode
SW1(config)#int range f0/23 - 24
SW1(config-if-range)#no shut
SW1(config-if-range)#
1d21h: %LINK-3-UPDOWN: Interface FastEthernet0/23, changed state to up
1d21h: %LINK-3-UPDOWN: Interface FastEthernet0/24, changed state to up
SW1#
1d21h: %SYS-5-CONFIG_I: Configured from console by console
SW1#
1d21h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/23,
changed state to up
1d21h: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24,
changed state to up
SW1#sh vtp st
VTP Version : 2
Configuration Revision : 6
Maximum VLANs supported locally : 1005
Number of existing VLANs : 9
VTP Operating Mode : Server
VTP Domain Name : cisco
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x95 0x2F 0xA2 0xC3 0x98 0x98 0x6E 0xFE
Configuration last modified by 0.0.0.0 at 3-2-93 21:17:22
Local updater ID is 0.0.0.0 (no valid interface found)
SW1#sh vlan
VLAN Name Status Ports
---- -------------------------------- --------- ---------
1 default active
10 VLAN0010 active
20 VLAN0020 active
30 VLAN0030 active
40 VLAN0040 active
This clearly shows a VTP client with a higher revision number adding VLANs
to the list on the server. I also set this up again and removed VLANs from
this client this time and when the interfaces came back up, they removed
VLANs from the server. I don't like this feature and really don't
understand why it would be coded this way but there it is.
Rik
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Carlos Mendioroz
Sent: Monday, March 13, 2006 8:50 PM
To: ccielab@groupstudy.com
Subject: VTP client overwriting server ?
Hi,
I've just received 2 conflicting pieces of information.
Well, both conflicted with what I supposed I knew...
1- IOS VTP clients do keep VLAN information in nvram
2- IOS VTP clients may overwrite a VTP server (so the message was, beware
even more than what you used to from vlan info from a shelf switch).
#1 I have confirmed. You pass some VLANs to a client, you isolate the
client, you reload the client... and you have your VLANs.
Cisco says you would not... well, at least says so in many places.
#2 I have been unable to reproduce... even having a client with higher
revision number talk to a server does not do the trick.
The client will keep its higher version though...
So here: Does anybody have conclusive info of #2 being true or false ?
In case it is true, would you mind sharing a list of steps to make it ?
Yours truly (confused :)
-Carlos
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