From: Dennis J. Hartmann (dennisjhartmann@hotmail.com)
Date: Thu Nov 10 2005 - 11:54:52 GMT-3
VTP transparent is used to "IGNORE" VTP advertisements coming over
trunk links. As previously discussed, there is NO way to completely turn
off VTP advertisements unless you filter the MAC address 01-00-0c-cc-cc-cc.
Be careful with that too! Since CDP, DTP, etc. also uses this well known
MAC address, you need to know what Protocol Cisco is using in the SNAP
header this particular type.
VTP packets are sent in either ISL frames or in dot1q frames. These packets
are sent to the destination MAC address 01-00-0C-CC-CC-CC with a Logical
Link Control (LLC) code of Subnetwork Access Protocol (SNAP) (AAAA) and a
type of 2003 (in the SNAP header). This is the format of a VTP packet
encapsulated in ISL frames:
From:
http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080
094c52.shtml
Sincerely,
Dennis J. Hartmann
White Pine Communications
dh8@pobox.com
CCSI#23402 / CCVP / CCIP / CCNP
Cisco Optical, VPN & IDS Specialist
MCSE
-----Original Message-----
From: De Witt, Duane [mailto:duane.dewitt@siemens.com]
Sent: Thursday, November 10, 2005 5:55 AM
To: Dennis J. Hartmann; brussels; Lee.Donald@t-systems.co.uk
Cc: noble@inserviceindia.com; ccielab@groupstudy.com
Subject: RE: VTP Question
Hi All
Is VTP v1 and transparent mode really required to prevent VTP packets from
leaving certain ports? I've always just set the ports to switchport mode
access since VTP can only run on trunks. Or is this only required to stop
the VTP packets over trunks as well?
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Dennis J. Hartmann
Sent: 10 November 2005 02:24 AM
To: 'brussels'; Lee.Donald@t-systems.co.uk
Cc: noble@inserviceindia.com; ccielab@groupstudy.com
Subject: RE: VTP Question
Version 1 is the default. I wanted to make sure everyone knows that
because this is not clear when using the show vtp status command. This
command will show VTP V2 Mode, but next to V2, it will display Disabled (see
below).
Switch> show vtp status
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs : 5
VTP Operating Mode : Server
VTP Domain Name :
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0xBF 0x86 0x94 0x45 0xFC 0xDF 0xB5 0x70 Configuration last
modified by 0.0.0.0 at 0-0-00 00:00:00 Local updater ID is 172.20.135.196 on
interface Vl1 (lowest numbered VLAN interface found)
Sincerely,
Dennis Hartmann
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
brussels
Sent: Tuesday, June 07, 2005 6:26 AM
To: Lee.Donald@t-systems.co.uk
Cc: noble@inserviceindia.com; ccielab@groupstudy.com
Subject: RE: VTP Question
This is not enough. All lab scenarios for training have trunk ports (either
two trunks or one ether-channel) and therefore VTP packets will be sent out
and recieved on some ports.
The solution is to set VTP mode to transparent and version 1. (V2 VTP switch
transparently forwards VTP packets, while V1 doesn't)
>Noble,
>
>I would deduce from this question that it wants to change each port to
>"switchport Access" mode so that VTP frames are not sent out, by
>default all ports will be dynamic.
>
>Regards
>
>Lee.
>
>
>
>-----Original Message-----
>From: T. N. Noble [mailto:noble@inserviceindia.com]
>Sent: 07 June 2005 10:51
>To: ccielab@groupstudy.com
>Subject: VTP Question
>
>Hello Group,
>
>Can anybody help me to understand the following question correctly?
>
>"Restrict the VTP Traffic from reaching all the 24 fast Ethernet ports
>of the switch". Is this question talking about VTP Pruning? I
>understand that the VTP pruning is related to Trunks where as here the
>switch ports are in Access Mode.
>
>Thanks,
>
>Noble
>
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