From: Scott Vermillion (scott_ccie_list.com@it-ag.com)
Date: Fri Sep 07 2007 - 23:05:08 ART
Hey, thanks. I don't recall any threads on this but I don't always read
every post in every thread (I try to read at least all of the opening posts
to see if I'm interested or not). Also, let's face it, archive search
function isn't what it used to be.
So the documentation is bunk. Not the first time...
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ISolveSystems
Sent: Friday, September 07, 2007 7:53 PM
To: Scott M Vermillion
Cc: Cisco certification
Subject: Re: Seemingly Simple VTP Question
There were couple of threads regarding this a few days ago. Check the
archive.
Basically, the Transparent switch at the middle has to have null domain name
or have domain name that's the same as the other switch for it to forward
the VTP info.
On 9/7/07, Scott M Vermillion <scott@it-ag.com> wrote:
>
> OK all, today I see some VTP behavior that I think is in contrast with my
> understanding of VTP, so I go to the DocCD > 3560 > Configuring
> VTP. There,
> I find:
>
>
>
> "In VTP Version 2, transparent switches do forward VTP advertisements that
> they receive from other switches through their trunk interfaces."
>
>
>
> Furthermore:
>
>
>
> "Version-Dependent Transparent Mode-In VTP Version 1, a VTP transparent
> switch inspects VTP messages for the domain name and version and forwards
> a
> message only if the version and domain name match. Because VTP Version 2
> supports only one domain, it forwards VTP messages in transparent mode
> without inspecting the version and domain name."
>
>
>
> Which is consistent with my understanding of VTP operation. I am easily
> able to verify the part about Ver 1 inspecting the version and domain name
> before forwarding summary advertisements. As for the statement regarding
> Ver 2.
>
>
>
> My lab is simple SW1 connected to both SW2 and SW4, with each of those
> connected to SW3 (the basic "diamond" you find in the Bridging and
> Switching
> section of IEWB#1, although this is not exactly any one of the labs found
> there). SW1 is the VTP server and it is running Ver 2 w/ domain name
> "CISCO." SW2 and SW4 are configured for transparent Ver 2 w/ domain name
> "TRANS." SW3 is configured for client and nothing more (should pick up
> Ver
> 2 from the VTP server). Everything is uncabled, vlan.dat is deleted, all
> switches rebooted, everything I just mentioned configured, then everything
> is cabled back up. Here, after a period much longer than the five-minute
> summary advertisement interval, is what I see at SW3:
>
>
>
> SW3#sh vtp stat
>
> VTP Version: running
> VTP1 (VTP2 capable)
>
> Configuration Revision: 0
>
> Maximum VLANs supported locally : 1005
>
> Number of existing VLANs: 5
>
> VTP Operating Mode: ClientVTP
>
> Domain Name: VTP
>
> Pruning Mode: Disabled
>
> VTP V2 Mode: Disabled
>
> VTP Traps Generation: Disabled
>
> MD5 digest: 0x57
> 0xCD
> 0x40 0x65 0x63 0x59 0x47 0xBD
>
> Configuration last modified by 0.0.0.0 at 0-0-00 00:00:00
>
> SW3#
>
>
>
>
>
> What is it about "because VTP Version 2 supports only one domain, it
> forwards VTP messages in transparent mode without inspecting the version
> and
> domain name" that I am failing to understand? I realize this is a pretty
> basic question to be asking the list, but I didn't have any switches in my
> lab during written prep, so I had to accept what I read without any kind
> of
> verification where L2 was concerned. Now I'm backtracking and trying to
> verify absolutely everything (hey, I invested heavily in these 3560s, I'm
> not leaving one single switching point on the table in any of my lab
> attempts!!). Am I just reading this totally wrong? Don't see how you
> could, but I suppose it's possible.
>
>
>
> Regards all,
>
>
> Scott
>
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