From: Fabrice Bobes (study@6colabs.com)
Date: Mon Oct 21 2002 - 00:19:45 GMT-3
Loizos,
This is a follow-up to the VTP domain thread.
I just did some testing between 2 Cat 3550 loaded with the EMI software
version 12.1(11)EA1.
Let's start with this link I took from Cisco:
http://www.cisco.com/en/US/products/hw/switches/ps646/products_configura
tion_guide_chapter09186a00800c6f52.html#xtocid29
It says: "Note You cannot remove VLAN 1 or VLANs 1002 to 1005 from the
allowed VLAN list."
Well, I agree that we can't remove VLANs 1002 to 1005 but there is no
problem issuing this command on the trunk:
switchport trunk allowed vlan remove 1
Now what happens when Vlan1 is removed from the trunk?
VTP doesn't work anymore, CDP neither.
My configuration is really straightforward.
Cat1 FA0/20 ---- Trunk (ISL or Dot1Q) ---- FA0/20 Cat2
Cat1 is the VTP Server
Cat2 is the VTP Client
On both sides, I manually configured a trunk and tried ISL and Dot1Q and
got the same results.
Int Fa0/20
switchport trunk encapsulation dot1q
switchport trunk native vlan 10
switchport trunk allowed vlan 10,20,30,40,50,1002-4094
switchport mode trunk
switchport nonegotiate
All this blabla to confirm that if you remove VLAN1 from a trunk, the
VTP messages don't transit anymore between the switches.
Fabrice
-----Original Message-----
From: LoizosCisco [mailto:david_steven2001@yahoo.com]
Sent: Saturday, October 19, 2002 10:03 PM
To: Fabrice Bobes
Subject: RE: VTP domain.
Thanks much Fabrice.
--- Fabrice Bobes <study@6colabs.com> wrote:
> Loizos,
>
> I am not an expert on anything, believe me :-)
> In our VTP scenario with server and client, we need
> VLAN1.
> If you plan to remove VLAN1 from the trunk, you need
> to remember that
> many control protocols needs it like DTP, CDP, PagP,
> VTP, ... Actually,
> I am reading the Cisco Doc and it says that if you
> disable VLAN1, the
> control protocols still go through. I'll test
> tomorrow on a pair of
> 3550.
> If you just need to trunk with a router on a stick,
> you don't necessary
> need VLAN1.
> A good habit anyway is to allow only the VLANS you
> need on the trunk.
>
> Fabrice
> -----Original Message-----
> From: LoizosCisco
> [mailto:david_steven2001@yahoo.com]
> Sent: Saturday, October 19, 2002 8:15 PM
> To: Fabrice Bobes; ccielab@groupstudy.com
> Subject: RE: VTP domain.
>
>
> Fabrice,
>
> Thanks for the reply.
> What if I am trunking to a router port and I have to
> only allow certain vlans to go through? If I specify
> the vlans and the 1002-1005 vlans and do not specify
> the vlan1 will that be a problem ? OR do I always
> have
> to specify 1002-1005, vlan 1 and the other vlans?
>
> In other words, should I make it a standard to have
> 1002-1005,1, plus
> the other vlans involved in trunking, everytime I
> have to allow specific
> vlans through a trunking port?
>
> I wish I had the two 3550s to practice myself but I
> do
> not. I will appreciate any info. You seem to be the
> expert on this 3550 vlan stuff :-)
>
> Thanks again
>
> Loizos
>
>
> --- Fabrice Bobes <study@6colabs.com> wrote:
> > Loizos,
> >
> > When you configure a trunk, the traffic for all
> the
> > vlans will be
> > transported by default.
> > You don't need to manually add VLAN1.
> > To confirm that VTP needs VLAN1 to transport its
> > messages, I have just
> > removed Vlan1 from the trunk, created a new VLAN
> on
> > the VTP server and,
> > as expected, the new VLAN didn't show up on the
> vtp
> > client.
> >
> > Fabrice
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> > [mailto:nobody@groupstudy.com] On Behalf Of
> > LoizosCisco
> > Sent: Saturday, October 19, 2002 5:53 PM
> > To: Fabrice Bobes; 'enginedrive2002';
> > ccielab@groupstudy.com
> > Subject: RE: VTP domain.
> >
> >
> > Fabrice,
> >
> > When I add vlans to Trunk I know I must add the
> > 1002-1005 and the other vlans that are involved in
> > trunking. Do I also need to add vlan1 or is it
> added
> > by default?
> >
> > Loizos
> >
> >
> > --- Fabrice Bobes <study@6colabs.com> wrote:
> > > This is correct, VTP is only carried over VLAN1.
> > > Obviously, you can't
> > > disable VLAN1 from the trunk when using vtp.
> > >
> > > Fabrice
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com
> > > [mailto:nobody@groupstudy.com] On Behalf Of
> > > enginedrive2002
> > > Sent: Saturday, October 19, 2002 2:16 PM
> > > To: ccielab@groupstudy.com
> > > Subject: Re: VTP domain.
> > >
> > >
> > > Thanks for the confirmation Fabrice and Stefan!
> > >
> > > I have another question about VTP: which vlan is
> > > used to
> > > transmit/receive VTP packets? I remember read
> from somewhere that it
> > > only use vlan1, is this true?
> > >
> > > Thanks!
> > >
> > >
> > > E.D.
> > >
> > > ----- Original Message -----
> > > From: "Stefan L. Dozier" <doziersl@yahoo.com>
> > > To: "Fabrice Bobes" <study@6colabs.com>;
> > <ccielab@groupstudy.com>
> > > Sent: October 19, 2002 3:48 PM
> > > Subject: RE: VTP domain.
> > >
> > >
> > > > Ok...I've completed testing and I concur with
> > your
> > > assessment and your
> > >
> > > > answer, that "vtp domain <domain name> on a
> > > configured client is "not"
> > >
> > > > a must!
> > > >
> > > > Given the situation, where the client switch
> is
> > in
> > > a default vtp
> > > > state, and it's vtp mode has been set to
> > "client",
> > > you can connect him
> > >
> > > > to a vtp server via a trunk link, and have him
> > > "inherit" the vtp
> > > > server's domain name.
> > > >
> > > > Good catch...I didn't know that, but I do now
> > :-)
> > > >
> > > > Thanks for testing and increasing my level of
> > > knowledge! I've always
> > > > set the domain name manually as well as ensure
> > the
> > > client was actually
> > >
> > > > a vtp client, before connecting them to the
> > > network, less you'll
> > > > possibly be struggling to bring your network
> > back
> > > from death due to
> > > > erasure of your vtp domain. :-)
> > > >
> > > > Stefan
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com
> > > [mailto:nobody@groupstudy.com]On Behalf Of
> > >
> > > > Fabrice Bobes
> > > > Sent: Saturday, October 19, 2002 2:39 PM
> > > > To: 'Stefan L. Dozier'; ccielab@groupstudy.com
> > > > Subject: RE: VTP domain.
> > > >
> > > >
> > > > Stefan,
> > > >
> > > > I can confirm that a vtp client in a default
> vtp
> > > state will get the
> > > > vtp server's domain name via a trunk. I tried
> > this
> > > on 2 of my
> > > > Catalysts 3550 not later than yesterday. No, I
> > > wasn't bored.
> > > >
> > > > Thanks for the comments,
> > > >
> > > > Fabrice
>
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