From: Church, Chuck (cchurch@netcogov.com)
Date: Wed Mar 15 2006 - 11:07:21 GMT-3
Could this be a 'feature' because the server is in an unconfigured
state? What if you did the same test, but before you brought the trunk
up between the two, you made a change (add a VLAN or rename one) to make
the revision number 1 or higher. I'm betting that it wouldn't do it.
Now that I think about it, perhaps it's intended use is if you had a
network with 1 server, and multiple clients. And that one server switch
dies, requiring replacement. If an unconfigured server can learn from
clients, that would speed up the recovery operation. Debugging VTP on
the server when you bring the trunk up might show some interesting stuff
too.
Chuck Church
Network Engineer
CCIE #8776, MCNE, MCSE
Netco Government Services
Enterprise Network Engineering
Home Office - 864-335-9473
Cell - 864-266-3978
cchurch@netcogov.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Guyler, Rik
Sent: Wednesday, March 15, 2006 8:51 AM
To: 'ccielab@groupstudy.com'
Subject: RE: VTP client overwriting server ?
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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